U.S. patent application number 17/064814 was filed with the patent office on 2022-03-17 for over-the-air testing interface for phase array antennas.
The applicant listed for this patent is NATIONAL INSTRUMENTS CORPORATION. Invention is credited to Chen Chang, David M. Crowley, Gerardo Orozco Valdes.
Application Number | 20220082601 17/064814 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-17 |
United States Patent
Application |
20220082601 |
Kind Code |
A1 |
Crowley; David M. ; et
al. |
March 17, 2022 |
Over-The-Air Testing Interface for Phase Array Antennas
Abstract
Various embodiments are presented of a system including an
alignment fixture for testing (e.g., rapidly and cheaply) phased
array antennas and other devices configured for radio frequency
(RF) transmission and/or reception. A device to be tested (e.g.,
the device under test (DUT)) may be positioned in a testing
position by the alignment fixture. The alignment fixture may
provide a configurable level of friction to retain the DUT in the
testing position. The alignment fixture may provide isolation from
electromagnetic interference for the DUT while in the testing
position.
Inventors: |
Crowley; David M.; (Cedar
Park, TX) ; Orozco Valdes; Gerardo; (Austin, TX)
; Chang; Chen; (Fremont, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NATIONAL INSTRUMENTS CORPORATION |
Austin |
TX |
US |
|
|
Appl. No.: |
17/064814 |
Filed: |
October 7, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63078769 |
Sep 15, 2020 |
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International
Class: |
G01R 29/10 20060101
G01R029/10; G01R 29/08 20060101 G01R029/08 |
Claims
1. An over-the-air (OTA) test apparatus, comprising: a gasket
interface; and a loadboard comprising: a mechanism for attachment
of device-under-test (DUT); a ground plane; and a conductive pad,
wherein the conductive pad is configured to contact the gasket
interface and electrically connect the gasket interface with the
ground plane when the loadboard is in a testing position, wherein
the ground plane, the gasket interface, and the conductive pad
provide electromagnetic isolation for the DUT in the testing
position.
2. The OTA test apparatus of claim 1, wherein the mechanism for
attachment of the DUT is configured so that the DUT may be inserted
from the top down.
3. The OTA test apparatus of claim 1, wherein the loadboard further
comprises one or more positioning pin and the mechanism for
attachment of the for the DUT comprises: a chamber interface plate
comprising one or more alignment slot for positioning the chamber
interface plate relative to the loadboard using the one or more
positioning pin.
4. The OTA test apparatus of claim 3, further comprising a spring,
wherein the spring produces a force on the chamber interface plate
so that a sliding friction between the chamber interface plate and
the loadboard resists vibration and maintains the DUT in a testing
position.
5. The OTA test apparatus of claim 3, wherein the chamber interface
plate consists of a low-friction material.
6. The OTA test apparatus of claim 3, wherein the chamber interface
plate is configured to slide relative to an anechoic chamber.
7. An over-the-air (OTA) test apparatus, comprising: an
electromagnetic shield, configured to provide electromagnetic
isolation for a device-under-test (DUT), when the DUT is in a
testing position; a loadboard, configured to exchange test
information with the DUT; a socket, configured to attach the DUT;
and an interface configured to position the DUT in the testing
position relative to an anechoic chamber, wherein the OTA test
apparatus is configured to allow for controlled motion of the DUT
in at least a first dimension when the OTA test apparatus brings
the DUT into the testing position via motion in a second
dimension.
8. The OTA test apparatus of claim 7, wherein the loadboard is a
printed circuit board (PCB).
9. The OTA test apparatus of claim 8, wherein the electromagnetic
shield is a groundplane of the PCB.
10. The OTA test apparatus of claim 8, wherein the electromagnetic
shield is distinct from the PCB.
11. The OTA test apparatus of claim 7, wherein the interface
comprises a chamber interface plate configured to slide in at least
the first dimension relative to the anechoic chamber.
12. The OTA test apparatus of claim 8, wherein a bottom portion of
the socket is integrated into the chamber interface plate.
13. The OTA test apparatus of claim 7, further comprising a
conductive pad coupled to the electromagnetic shield, wherein the
conductive pad is configured to contact a gasket, wherein the
electromagnetic isolation is provided by the electromagnetic shield
in combination with the conductive pad and the gasket.
14. The OTA test apparatus of claim 7, further comprising a handler
interface bracket comprising a sliding mechanism configured to
slide in at least the first dimension.
15. The OTA test apparatus of claim 7, wherein the OTA test
apparatus is further configured to allow for controlled motion of
the DUT in at least a third dimension when the OTA test apparatus
brings the DUT into the testing position via the motion in the
second dimension.
16. The OTA test apparatus of claim 7, wherein the interface
comprises a chamber interface plate mounted in a fixed position
relative to the anechoic chamber, wherein the OTA test apparatus
further comprises a handler interface bracket configured to slide
in at least the first dimension relative to the anechoic
chamber.
17. An over-the-air (OTA) test system, comprising: an anechoic
chamber, comprising a radio frequency (RF) gasket; an interface
configured to position a device-under-test (DUT) in a testing
position relative to the anechoic chamber, wherein the interface
comprises an RF transparent plastic, wherein the interface is
configured to slide in at least one dimension relative to the
anechoic chamber; a socket to provide an electrical connection to
the DUT; and a loadboard, comprising a conductive pad connected to
a groundplane of the loadboard, wherein the conductive pad is
configured to contact the RF gasket when the DUT is in the testing
position.
18. The OTA test system of claim 17, wherein the RF gasket,
conductive pad, and the groundplane provide electromagnetic
compatibility for the DUT in the testing position.
19. The OTA test system of claim 17, wherein the at least one
dimension is parallel to an opening of the anechoic chamber.
20. The OTA test system of claim 17, further comprising a handler
configured to bring the DUT to the testing position, wherein to
bring the DUT to the testing position includes lowering the DUT to
the testing position from above.
Description
PRIORITY CLAIM
[0001] This application claims priority to U.S. provisional patent
application Ser. No. 63/078,769, entitled "Over-The-Air Testing
Interface for Phase Array Antennas," filed Sep. 15, 2020, which is
hereby incorporated by reference in its entirety as though fully
and completely set forth herein.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of semiconductor
testing, and more specifically, to testing of phase array
antennas.
DESCRIPTION OF THE RELATED ART
[0003] Millimeter wave (mmW) technology is rapidly growing in
importance, e.g., as 5.sup.th generation (5G) wireless technology
is becoming more widespread. Current methods for testing integrated
circuits with integrated antennas for transmitting and/or receiving
mmW signals may be slow and/or expensive.
[0004] The scalability of 5G may depend on reducing cost in various
areas. One particular new item in 5G mmWave is that the conductive
test may not be achieved as there may be no probes to the device.
However, Over The Air (OTA) testing may be possible. 5G devices may
have multiple phase arrays and each phase array may consist of
multiple antennas (e.g., for beamforming, multiple-in-multiple-out
(MIMO), and/or massive MIMO) to produce a beam pattern with a large
gain and overcome pathloss issues at mmWave.
[0005] To efficiently test such devices (e.g., phase array
antennas) in high volume production, each device needs to be
validated independently to ensure quality. To scale this process,
many devices devices will need to be tested within a window of time
making manufacturing test time one of the key elements to achieve
for these devices.
[0006] Functional testing and parametric testing may be difficult
to integrate with existing automatic testing equipment (ATE)
handlers. OTA chambers may be difficult to incorporate into
production testing due to scalability constraints.
[0007] Some test methods may only test individual elements of these
phase arrays and therefore they focus on functionality of each
individual element and not all of antennas (e.g., and thus may not
test the beamforming capability of the array).
[0008] Further, some current methods may not correlate well with
the accepted 3GPP Direct Far Field methods. Moreover, some
measurements may be impacted by the measurement antenna adding
extra uncertainty to the results. It may be difficult or impossible
to do parametric measurements on an entire phase array. Parametric
tests may test individual elements functionality, but not the
module as a whole.
[0009] Improvements in the field are desired.
SUMMARY OF THE INVENTION
[0010] Various embodiments are presented below of a system and
method for testing (e.g., rapidly and cheaply) devices with phased
array antennas, e.g., such as integrated circuits (IC) with
integrated antennas configured for millimeter wave (mmW)
transmission and/or reception. A level of friction may be
determined for a specific type of device under test (DUT)). An
alignment fixture may be configured to provide the desired level of
friction. The alignment fixture may be modular, e.g., so that
portions of the alignment fixture can be exchanged to accommodate
particular types of DUT(s). For example, portions may be exchanged
to accommodate different size or shape of DUTs as well as different
desired levels of friction. The alignment fixture may be
sufficiently rigid to withstand a large number of testing cycles.
The alignment fixture may incorporate space for additional
equipment. The alignment fixture may determine if the DUT is
positioned correctly relative to the alignment fixture.
[0011] The alignment fixture may position the DUT(s) in a testing
position, e.g., relative to an anechoic chamber. While in the
testing position, the alignment fixture may isolate the DUT(s) from
electromagnetic interference and may provide the desired level of
friction. The DUT(s) capabilities to transmit and/or receive
beamformed signals may be tested.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A better understanding of the present invention can be
obtained when the following detailed description of the preferred
embodiment is considered in conjunction with the following
drawings, in which:
[0013] FIG. 1 illustrates a computer system configured to perform
testing of an integrated circuit, according to some
embodiments.
[0014] FIG. 2A illustrates an instrumentation control system
according to some embodiments.
[0015] FIG. 2B illustrates an industrial automation system
according to some embodiments.
[0016] FIG. 3 is an exemplary block diagram of the computer systems
of FIGS. 1, 2A, and 2B, according to some embodiments.
[0017] FIGS. 4-9 illustrate exemplary integrated circuits,
according to some embodiments.
[0018] FIGS. 10-16 illustrate aspect of testing millimeter wave
integrated circuit radio frequency performance, according to some
embodiments.
[0019] FIGS. 17-24 illustrate various aspects of methods and
systems for over-the-air testing of phased array antennas,
according to some embodiments.
[0020] FIGS. 25-30 illustrate various aspects of example systems
for over-the-air testing of phased array antennas, according to
some embodiments.
[0021] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof are shown by
way of example in the drawings and are herein described in detail.
It should be understood, however, that the drawings and detailed
description thereto are not intended to limit the invention to the
particular form disclosed, but on the contrary, the intention is to
cover all modifications, equivalents and alternatives falling
within the spirit and scope of the present invention as defined by
the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
Terms
[0022] The following is a glossary of terms used in the present
application:
[0023] Memory Medium--Any of various types of non-transitory
computer accessible memory devices or storage devices. The term
"memory medium" is intended to include an installation medium,
e.g., a CD-ROM, floppy disks 104, or tape device; a computer system
memory or random access memory such as DRAM, DDR RAM, SRAM, EDO
RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,
magnetic media, e.g., a hard drive, or optical storage; registers,
or other similar types of memory elements, etc. The memory medium
may comprise other types of non-transitory memory as well or
combinations thereof. In addition, the memory medium may be located
in a first computer in which the programs are executed, or may be
located in a second different computer which connects to the first
computer over a network, such as the Internet. In the latter
instance, the second computer may provide program instructions to
the first computer for execution. The term "memory medium" may
include two or more memory mediums which may reside in different
locations, e.g., in different computers that are connected over a
network.
[0024] Carrier Medium--a memory medium as described above, as well
as a physical transmission medium, such as a bus, network, and/or
other physical transmission medium that conveys signals such as
electrical, electromagnetic, or digital signals.
[0025] Programmable Hardware Element--includes various hardware
devices comprising multiple programmable function blocks connected
via a programmable interconnect. Examples include FPGAs (Field
Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs
(Field Programmable Object Arrays), and CPLDs (Complex PLDs). The
programmable function blocks may range from fine grained
(combinatorial logic or look up tables) to coarse grained
(arithmetic logic units or processor cores). A programmable
hardware element may also be referred to as "reconfigurable
logic."
[0026] Processing Element--refers to various elements or
combinations of elements that are capable of performing a function
in a device, such as a user equipment or a cellular network device.
Processing elements may include, for example: processors and
associated memory, portions or circuits of individual processor
cores, entire processor cores, processor arrays, circuits such as
an ASIC (Application Specific Integrated Circuit), programmable
hardware elements such as a field programmable gate array (FPGA),
as well any of various combinations of the above.
[0027] Software Program--the term "software program" is intended to
have the full breadth of its ordinary meaning, and includes any
type of program instructions, code, script and/or data, or
combinations thereof, that may be stored in a memory medium and
executed by a processor. Exemplary software programs include
programs written in text-based programming languages, such as C,
C++, PASCAL, FORTRAN, COBOL, JAVA, assembly language, etc.;
graphical programs (programs written in graphical programming
languages); assembly language programs; programs that have been
compiled to machine language; scripts; and other types of
executable software. A software program may comprise two or more
software programs that interoperate in some manner. Note that
various embodiments described herein may be implemented by a
computer or software program. A software program may be stored as
program instructions on a memory medium.
[0028] Hardware Configuration Program--a program, e.g., a netlist
or bit file, that can be used to program or configure a
programmable hardware element.
[0029] Program--the term "program" is intended to have the full
breadth of its ordinary meaning. The term "program" includes 1) a
software program which may be stored in a memory and is executable
by a processor or 2) a hardware configuration program useable for
configuring a programmable hardware element.
[0030] Computer System--any of various types of computing or
processing systems, including a personal computer system (PC),
mainframe computer system, workstation, network appliance, Internet
appliance, personal digital assistant (PDA), television system,
grid computing system, or other device or combinations of devices.
In general, the term "computer system" can be broadly defined to
encompass any device (or combination of devices) having at least
one processor that executes instructions from a memory medium.
[0031] Measurement Device--includes instruments, data acquisition
devices, smart sensors, and any of various types of devices that
are configured to acquire and/or store data. A measurement device
may also optionally be further configured to analyze or process the
acquired or stored data. Examples of a measurement device include
an instrument, such as a traditional stand-alone "box" instrument,
a computer-based instrument (instrument on a card) or external
instrument, a data acquisition card, a device external to a
computer that operates similarly to a data acquisition card, a
smart sensor, one or more DAQ or measurement cards or modules in a
chassis, an image acquisition device, such as an image acquisition
(or machine vision) card (also called a video capture board) or
smart camera, a motion control device, a robot having machine
vision, and other similar types of devices. Exemplary "stand-alone"
instruments include oscilloscopes, multimeters, signal analyzers,
arbitrary waveform generators, spectroscopes, and similar
measurement, test, or automation instruments.
[0032] A measurement device may be further configured to perform
control functions, e.g., in response to analysis of the acquired or
stored data. For example, the measurement device may send a control
signal to an external system, such as a motion control system or to
a sensor, in response to particular data. A measurement device may
also be configured to perform automation functions, i.e., may
receive and analyze data, and issue automation control signals in
response.
[0033] Functional Unit (or Processing Element)--refers to various
elements or combinations of elements. Processing elements include,
for example, circuits such as an ASIC (Application Specific
Integrated Circuit), portions or circuits of individual processor
cores, entire processor cores, individual processors, programmable
hardware devices such as a field programmable gate array (FPGA),
and/or larger portions of systems that include multiple processors,
as well as any combinations thereof.
[0034] Automatically--refers to an action or operation performed by
a computer system (e.g., software executed by the computer system)
or device (e.g., circuitry, programmable hardware elements, ASICs,
etc.), without user input directly specifying or performing the
action or operation. Thus the term "automatically" is in contrast
to an operation being manually performed or specified by the user,
where the user provides input to directly perform the operation. An
automatic procedure may be initiated by input provided by the user,
but the subsequent actions that are performed "automatically" are
not specified by the user, i.e., are not performed "manually,"
wherein the user specifies each action to perform. For example, a
user filling out an electronic form by selecting each field and
providing input specifying information (e.g., by typing
information, selecting check boxes, radio selections, etc.) is
filling out the form manually, even though the computer system must
update the form in response to the user actions. The form may be
automatically filled out by the computer system where the computer
system (e.g., software executing on the computer system) analyzes
the fields of the form and fills in the form without any user input
specifying the answers to the fields. As indicated above, the user
may invoke the automatic filling of the form, but is not involved
in the actual filling of the form (e.g., the user is not manually
specifying answers to fields but rather they are being
automatically completed). The present specification provides
various examples of operations being automatically performed in
response to actions the user has taken.
[0035] Concurrent--refers to parallel execution or performance,
where tasks, processes, or programs are performed in an at least
partially overlapping manner. For example, concurrency may be
implemented using "strong" or strict parallelism, where tasks are
performed (at least partially) in parallel on respective
computational elements, or using "weak parallelism," where the
tasks are performed in an interleaved manner, e.g., by time
multiplexing of execution threads.
[0036] Wireless--refers to a communications, monitoring, or control
system in which electromagnetic or acoustic waves carry a signal
through space rather than along a wire.
[0037] Approximately--refers to a value being within some specified
tolerance or acceptable margin of error or uncertainty of a target
value, where the specific tolerance or margin is generally
dependent on the application. Thus, for example, in various
applications or embodiments, the term approximately may mean:
within 0.1% of the target value, within 0.2% of the target value,
within 0.5% of the target value, within 1%, 2%, 5%, or 10% of the
target value, and so forth, as required by the particular
application of the present techniques.
FIG. 1A--Computer System
[0038] FIG. 1A illustrates a computer system 82 configured to
implement embodiments of the techniques disclosed herein.
Embodiments of a method for (e.g., for production testing of
integrated circuits) are described below. Note that various
embodiments of the techniques disclosed herein may be implemented
in a variety of different ways. For example, in some embodiments,
some or all of the techniques may be implemented with textual or
graphical programs that may be deployed to, or used to configure,
any of various hardware devices.
[0039] However, while some embodiments are described in terms of
one or more programs, e.g., graphical programs, executing on a
computer, e.g., computer system 82, these embodiments are exemplary
only, and are not intended to limit the techniques to any
particular implementation or platform. Thus, for example, in some
embodiments, the techniques may be implemented on or by a
functional unit (also referred to herein as a processing element),
which may include, for example, circuits such as an ASIC
(Application Specific Integrated Circuit), portions or circuits of
individual processor cores, entire processor cores, individual
processors, programmable hardware devices such as a field
programmable gate array (FPGA), and/or larger portions of systems
that include multiple processors, as well as any combinations
thereof.
[0040] As shown in FIG. 1, the computer system 82 may include a
display device configured to display a graphical program as the
graphical program is created and/or executed. The display device
may also be configured to display a graphical user interface or
front panel of the graphical program during execution of the
graphical program. The graphical user interface may comprise any
type of graphical user interface, e.g., depending on the computing
platform.
[0041] The computer system 82 may include at least one memory
medium on which one or more computer programs or software
components according to one embodiment of the present invention may
be stored. For example, the memory medium may store one or more
programs, such as graphical programs, that are executable to
perform the methods described herein. The memory medium may also
store operating system software, as well as other software for
operation of the computer system. Various embodiments further
include receiving or storing instructions and/or data implemented
in accordance with the foregoing description upon a carrier
medium.
Exemplary Systems
[0042] Embodiments of the present invention may be involved with
performing test and/or measurement functions; controlling and/or
modeling instrumentation or industrial automation hardware;
modeling and simulation functions, e.g., modeling or simulating a
device or product being developed or tested, etc. Exemplary test
applications include hardware-in-the-loop testing and rapid control
prototyping, among others.
[0043] However, it is noted that embodiments of the present
invention can be used for a plethora of applications and is not
limited to the above applications. In other words, applications
discussed in the present description are exemplary only, and
embodiments of the present invention may be used in any of various
types of systems. Thus, embodiments of the system and method of the
present invention is configured to be used in any of various types
of applications, including the control of other types of devices
such as multimedia devices, video devices, audio devices, telephony
devices, Internet devices, etc., as well as general purpose
software applications such as word processing, spreadsheets,
network control, network monitoring, financial applications, games,
etc.
[0044] FIG. 2A illustrates an exemplary instrumentation control
system 100 which may implement embodiments described herein. The
system 100 comprises a host computer 82 which couples to one or
more instruments. The host computer 82 may comprise a CPU, a
display screen, memory, and one or more input devices such as a
mouse or keyboard as shown. The computer 82 may operate with the
one or more instruments to analyze, measure or control a unit under
test (UUT) or process 150, e.g., via execution of software 104.
[0045] The one or more instruments may include a GPIB instrument
112 and associated GPIB interface card 122, a data acquisition
board 114 inserted into or otherwise coupled with chassis 124 with
associated signal conditioning circuitry 126, a VXI instrument 116,
a PXI instrument 118, a video device or camera 132 and associated
image acquisition (or machine vision) card 134, a motion control
device 136 and associated motion control interface card 138, and/or
one or more computer based instrument cards 142, among other types
of devices. The computer system may couple to and operate with one
or more of these instruments. The instruments may be coupled to the
device under test (DUT) or process 150, or may be coupled to
receive field signals, typically generated by transducers. The
system 100 may be used in a data acquisition and control
application, in a test and measurement application, an image
processing or machine vision application, a process control
application, a man-machine interface application, a simulation
application, or a hardware-in-the-loop validation application,
among others.
[0046] FIG. 2B illustrates an exemplary industrial automation
system 200 which may implement embodiments described herein. The
industrial automation system 200 is similar to the instrumentation
or test and measurement system 100 shown in FIG. 2A. Elements which
are similar or identical to elements in FIG. 2A have the same
reference numerals for convenience. The system 200 may comprise a
computer 82 which couples to one or more devices or instruments.
The computer 82 may comprise a CPU, a display screen, memory, and
one or more input devices such as a mouse or keyboard as shown. The
computer 82 may operate with the one or more devices to perform an
automation function with respect to a process or device 150, such
as HMI (Human Machine Interface), SCADA (Supervisory Control and
Data Acquisition), portable or distributed data acquisition,
process control, advanced analysis, or other control, among others,
e.g., via execution of software 104.
[0047] The one or more devices may include a data acquisition board
114 inserted into or otherwise coupled with chassis 124 with
associated signal conditioning circuitry 126, a PXI instrument 118,
a video device 132 and associated image acquisition card 134, a
motion control device 136 and associated motion control interface
card 138, a fieldbus device 270 and associated fieldbus interface
card 172, a PLC (Programmable Logic Controller) 176, a serial
instrument 282 and associated serial interface card 184, or a
distributed data acquisition system, such as Fieldpoint system 185,
available from National Instruments Corporation, among other types
of devices.
[0048] In the embodiments of FIGS. 2A and 2B, above, one or more of
the various devices may couple to each other over a network, such
as the Internet. In one embodiment, the user operates to select a
target device from a plurality of possible target devices for
programming or configuration. Thus the user may create a program on
a computer and use (execute) the program on that computer or deploy
the program to a target device (for remote execution on the target
device) that is remotely located from the computer and coupled to
the computer through a network.
[0049] Software programs that perform data acquisition, analysis
and/or presentation, e.g., for measurement, instrumentation
control, industrial automation, modeling, or simulation, such as in
the applications shown in FIGS. 2A and 2B, may be referred to as
virtual instruments.
FIG. 3--Computer System Block Diagram
[0050] FIG. 3 is a block diagram 12 representing one embodiment of
the computer system 82 illustrated in FIG. 1, 2A or 2B. It is noted
that any type of computer system configuration or architecture can
be used as desired, and FIG. 4 illustrates a representative PC
embodiment. It is also noted that the computer system may be a
general purpose computer system, a computer implemented on a card
installed in a chassis, or other types of embodiments. Elements of
a computer not necessary to understand the present description have
been omitted for simplicity.
[0051] The computer may include at least one central processing
unit or CPU (processor) 160 which is coupled to a processor or host
bus 162. The CPU 160 may be any of various types, including any
type of processor (or multiple processors), as well as other
features. A memory medium, typically comprising RAM and referred to
as main memory, 166 is coupled to the host bus 162 by means of
memory controller 164. The main memory 166 may store a program
(e.g., a graphical program) configured to implement embodiments of
the present techniques. The main memory may also store operating
system software, as well as other software for operation of the
computer system.
[0052] The host bus 162 may be coupled to an expansion or
input/output bus 170 by means of a bus controller 168 or bus bridge
logic. The expansion bus 170 may be the PCI (Peripheral Component
Interconnect) expansion bus, although other bus types can be used.
The expansion bus 170 includes slots for various devices such as
described above. The computer 82 further comprises a video display
subsystem 180 and hard drive 182 coupled to the expansion bus 170.
The computer 82 may also comprise a GPIB card 122 coupled to a GPIB
bus 112, and/or an MXI device 186 coupled to a VXI chassis 116.
[0053] As shown, a device 190 may also be connected to the
computer. The device 190 may include a processor and memory which
may execute a real time operating system. The device 190 may also
or instead comprise a programmable hardware element. The computer
system may be configured to deploy a program to the device 190 for
execution of the program on the device 190. The deployed program
may take the form of graphical program instructions or data
structures that directly represents the graphical program.
Alternatively, the deployed program may take the form of text code
(e.g., C code) generated from the program. As another example, the
deployed program may take the form of compiled code generated from
either the program or from text code that in turn was generated
from the program.
FIGS. 4-9--Integrated Circuit (IC) with Antennas
[0054] Integrated circuits (IC) with integrated antennas are
increasingly common. Such ICs are included in many devices and may
be configured to perform various functions including wireless
communication (e.g., including transmission and/or reception) and
radar. In particular, 5G wireless communication standards (or other
standards) may provide for the use of millimeter wave (mmW) band
wireless signals and beamforming (e.g., directional
transmission/reception). ICs or application specific ICs (ASICs)
may be an important element of many wireless devices configured to
communicate using such standards. For example, an IC with an
integrated array of antennas (e.g., a phased array) may be a common
means of including such 5G wireless capabilities. Further, some ICs
may include multiple arrays of antennas.
[0055] FIG. 4 illustrates a phased array of antennas which may be
incorporated into an IC such as a complementary
metal-oxide-semiconductor (CMOS) Monolithic Microwave Integrated
Circuit (MMIC). As illustrated the IC may be approximately 1 cm by
1 cm, among various possibilities.
[0056] FIG. 5 illustrates an exemplary IC, including an integrated
antenna array (502). Such an IC may be approximately 2.5 cm wide,
among various possibilities. The IC may include wired and/or
wireless connections (504) for data, control, and power.
[0057] FIG. 6 illustrates an exemplary array of 256 antennas on a
chip. The array may be approximately 4 cm wide, among various
possibilities. It should be noted that other numbers or
configurations of antennas are possible, as well as other sizes of
chips. Further, the antennas may be on-chip, on-package, or even
located on a separate physical structure, according to some
embodiments.
[0058] FIG. 7 illustrates an exemplary IC. As shown, the IC
includes multiple (e.g., any desired number) of antenna patches
(702) mounted to a chip (704) (e.g., a printed circuit board (PCB),
glass wafer, silicon wafer, etc.). The antenna patches may transmit
signals to and from an integrated RF chip (or chips) (706). Note
that the RF chip (706) may be included in the chip (704), but may
not reach the full thickness of the chip (704). In the illustrated
example, the RF chip (706) reaches height h1, which is less than
the full height of the chip (704), h2. The RF chip (706) may be
connected to other elements of the IC, e.g., via wired
connections.
[0059] FIG. 8 illustrates different types of antenna connections of
exemplary ICs. In a first configuration (802), antennas may be
embedded in a printed circuit board (PCB), to which RF chips and a
heat sink are mounted. Such a configuration may be useful for
relatively low frequencies, e.g., approximately 75 GHz, according
to some embodiments. In a second configuration (804), antenna
patches may be embedded in package tiles, which are in turn mounted
to RF chips and a (e.g., 2nd level) PCB. The RF chips may be
connected (thru the PCB) to a heat sink. Such a configuration may
be useful for medium frequencies, e.g. 94 GHz, among various
possibilities. A third configuration (806) may include antenna
patches embedded in a glass substrate and stacked on RF chips,
e.g., above a package, 2.sup.nd level PCB, and heat sink. In a
variation, the glass wafer may be mounted on a silicon wafer
instead of a package. Such configurations may be useful for higher
frequencies, e.g., 110 GHz and above, among various
possibilities.
[0060] FIG. 9 illustrates an exemplary mmW IC (902) with an
integrated antenna array (904). As shown, each antenna element
(e.g., patch) (906) may have dedicated (e.g., per element)
circuitry (908). Note that the specific antenna element circuitry
shown is exemplary only, and that other circuit configurations may
be used.
FIGS. 10-16--Testing of mmW IC RF Performance
[0061] As demand for ICs with integrated antenna arrays grows,
improvements in the cost of producing and testing such ICs are
desired. Testing of mmW ICs, e.g., according to conventional
techniques, may be challenging for various reasons. There may be no
physical (e.g., wired) connections such as coax, waveguide or pins
with which to connect the antennas to test equipment. However,
power and control connections may be made using conventional, e.g.,
wired methods. Therefore, the radio frequency (RF) performance
(e.g., mmW transmission and reception) must be tested over-the-air.
Anechoic chambers may be a common technique to avoid interference,
e.g., due to reflected signals and multipath effects that can
complicate test measurements. However, in order to avoid RF
coupling (e.g., interference of the testing equipment with the
performance of the antenna array), the testing equipment may
require significant space. Further, beamforming requirements may
lead to many antennas on a package or on a chip and it may be
desired to test the beamforming directional capabilities of the
antenna array/IC. Testing of the beamforming capabilities may be
expensive, time-consuming, or difficult, e.g., to take measurements
from a potentially large number of positions, e.g., because the RF
performance may vary spatially. In other words, in order to test
the spatial RF performance, measurements must be taken in many
positions (e.g., in 3 dimensions, e.g., as a function of x, y, and
z position). Such detailed spatial testing may require complex
calibration. Still further, a relatively large distance (e.g., away
from the antenna array) may be needed to measure a fully formed
beam, and small anechoic chambers may not allow measurement in the
far field of the array (e.g., where the beam may be fully
formed).
[0062] FIG. 10 illustrates certain aspects of over-the-air testing
of RF performance, according to some embodiments. An entire array
may be tested, e.g., using an antenna (1002a and 1002b), e.g., a
horn antenna as illustrated or other type of antenna (e.g., patch,
dipole, loop, directional array, etc.). In order to test the
beamforming capability of the array, the antenna (or antennas) may
be positioned at a sufficiently large measurement distance (1004)
that the beam is fully formed. Further, measurements may be taken
from a variety of different positions in order to test the
performance of the beam in different directions. An entire array
test (1006a) may involve relatively high power signals, e.g., +40
dB (e.g., Equivalent Isotropically Radiated Power (EIRP)), as
shown, among various possibilities. The array of antennas may have
a power gain (e.g., array gain) relative to a single antenna.
Alternatively, single element tests (1006b) may be performed. A
test may require that the horn antenna be far enough away from the
antenna element(s) to be tested to avoid RF coupling. This distance
may be smaller for a single element test than the distance for beam
formation, e.g., for an entire array test. A single element test
may not test the beamforming performance of the array. Single
element tests may involve relatively low power signals, e.g., -10
dB, as shown, among various possibilities.
[0063] FIG. 11 illustrates fields generated by a short dipole
antenna, specifically the wave impedance as a function of distance
from the antenna. A "short" dipole may be one where its length is
(e.g., much) shorter than 1/2 wavelength. For the far field, where
the distance is greater than the wavelength, the following
relations may hold:
[0064] E/H=377, for r/.lamda.>1, where E is electric field, H is
magnetic field, r is radius, and A is wavelength;
[0065] E and H reduce as 1/r; and
[0066] Power drops as 1/r{circumflex over ( )}2.
[0067] For the near field, either the magnetic field or the
electric field may dominate. A conductor placed in the near field
reactive region may couple electrically or magnetically (e.g.,
Reactive coupling) and load down the source driving the antenna.
For example, test equipment placed in the near field region may
interfere with the operation of the antenna, due to reactive
coupling.
[0068] FIG. 12 illustrates fields generated by a short dipole
antenna, with further detail of different regions, e.g., as a
function of distance from the antenna. In the near-field radiative
and transition regions, E and H may reduce as 1/rAn, where n varies
from 1 to 6.
[0069] FIG. 13 illustrates radiation zones for antennas larger than
half a wavelength, e.g., in contrast to a short dipole antenna. In
some embodiments, the length of an individual antenna patch (1302),
e.g., as incorporated in an mmW IC, may be approximately equal to
half a wavelength. However, an array of such antennas may be (e.g.,
much) larger than half a wavelength. Therefore, such an antenna
array may exhibit characteristics similar to a single antenna
larger than half a wavelength, e.g., as illustrated. The near field
(e.g., reactive) region (1304) may be defined as:
r .ltoreq. 0.62 .times. D 3 .lamda. , ##EQU00001##
where D is the length of the antenna. Conductors in this region may
load down the antenna and significantly change the radiation
pattern.
[0070] The Fresnel (or transition) region (1306) may be defined
as:
0.62 .times. D 3 .lamda. < r .ltoreq. 2 .times. D 2 .lamda.
##EQU00002##
[0071] The radiation pattern may not be fully formed in this
region. Conductors in this region may not significantly change the
radiation pattern.
[0072] The radiating far field region may be defined as:
r > 2 .times. D 2 .lamda. ##EQU00003##
[0073] The radiation pattern (1308) may be fully formed in this
region.
[0074] FIG. 14 illustrates the radiation pattern of an exemplary
array of 4 antenna elements. Note that the radiation pattern is not
fully formed close to the antennas, and becomes clearer (e.g., more
fully formed) at increasing distance.
[0075] FIGS. 15 and 16 illustrate the boundary of a near field and
far field regions (e.g., respectively) for a 5 cm (e.g., square)
antenna array as a function of frequency (in GHz). Receiving
antennas (e.g., such as testing equipment) may significantly affect
the pattern when placed in the reactive near field, e.g., due to RF
coupling, e.g., reactive (capacitive or magnetic) coupling.
Receiving antennas may not significantly affect the pattern when
placed in far field, e.g., because power in the far field is
radiated into space. The pattern may not be fully formed in between
the near field boundary and the far field boundary (e.g., in the
transition zone or Fresnel region, e.g., at distances greater than
the near field boundary of FIG. 15 but less than the far field
boundary of FIG. 16), but it may not be significantly affected by a
receiving antenna. The transition zone may be the far field for
each element. However, the (e.g., combined) beam may not be fully
formed in this range, e.g., the beam pattern may be different from
near field or far field beam patterns.
[0076] For example, consider a 30 GHz transmission, e.g., which may
be common in a 5G communication system. As shown in FIG. 15, the
near field region may end at approximately 7 cm away from the
antenna array. The far field region may begin at approximately 50
cm away from the antenna array. Therefore, for the exemplary case
of a 30 GHz transmission associated with a 5 cm array, the
transition zone may be the zone between 7 and 50 cm from the
antenna array. It is noted that other array sizes and frequencies
are possible, that the techniques and systems disclosed herein may
be applied to other sizes and frequencies as desired, and that the
zone boundaries may vary, e.g., based on size and frequency.
Over-the-Air (OTA) Production Testing
[0077] An alignment fixture, e.g., as described herein, may be used
for production testing of phase array antennas. An alignment
fixture may integrate a (e.g., off the shelf) System Level Test
handler with an (e.g., off the shelf) anechoic mini chamber and
instruments to test the phase array antennas. The alignment fixture
may include interfaces between the chamber and the handler.
[0078] The alignment fixture may provide any combination of the
following features (and/or other features), according to some
embodiments.
[0079] Alignment. The device under test (DUT) (e.g., a phase
antenna array such as a mmW IC) may be extremely small and the
tolerances (e.g., for position of the DUT) may be small (e.g., less
100 microns), according to some embodiments. The alignment fixture
may serve to align the DUT(s) to the chamber, e.g., in a desired
testing position. The alignment may be so that radio frequency (RF)
probes can correctly touch the DUT. The RF probes may be small
probes that may be part of the socket. The RF probes may touch the
electrical connections of the DUT and may make the connection to
the loadboard. For example, electrical signals (e.g., input and/or
output signals) to and/or from the DUT may may transmitted using
the RF probes during testing.
[0080] Isolation. Electromagnetic isolation (EMI) of the DUT into
the chamber during testing may be important to ensuring valid test
results.
[0081] Rigidity. The design may last many (e.g., multiple million)
cycles without repair.
[0082] Adapt to multiple DUT specifics. The alignment fixture may
be configurable/adjustable to accommodate different DUTs. The DUTs
may be phase array antennas also called Antenna Under Test
(AUT).
[0083] DUT Detection. To make sure the DUT is in place correctly
before the handler engages, a mechanism may be used to produce a
"correct placement" signal. For example, the alignment fixture may
include a mechanism for detecting whether a DUT is placed
correctly. Such a mechanism could rely on any combination of
mechanical, electrical, magnetic, and/or optical sensors.
[0084] FIG. 17 illustrates a high level view of a test system
including the alignment fixture, according to some embodiments. It
will be appreciated that FIG. 17 is not to scale and that the
illustrated elements, relationships, dimensions, and measurements
are only examples. Additional or different elements may be included
and/or some illustrated elements may be omitted, according to some
embodiments. Further, elements may be arranged differently than
shown, according to some embodiments. In some embodiments, the test
antennas may be positioned at a far field distance relative to the
DUT (and vice versa). In some embodiments, the test antennas may be
positioned in a transition zone or Fresnel region.
[0085] As shown, the test system may include an anechoic chamber
with a number of test antennas located in different regions of the
chamber. The test antennas may be connected to various instruments.
The test system may also include a handler, e.g., configured to
approximately position one or more DUT in a testing position. The
test system may also include an alignment fixture to position the
DUT more precisely in the test position, reduce vibration during
testing, and isolate the DUT from electromagnetic interference
during testing.
[0086] The alignment fixture may include an interface to the
anechoic chamber. The interface may be a chamber interface plate
such as a chamber interface plate, e.g., to guide the DUT(s) into a
precise testing position and to retain the DUT in the testing
position during testing. a loadboard (e.g., a printed circuit board
(PCB) that may connect measurement instruments to the DUT, e.g.,
via socket/contactor). The loadboard may have loads, filters, and
signal conditioning electronics populated on it. The alignment
fixture may include a socket (e.g., or sockets) for attaching the
DUT(s). The socket may include separate (or separable) top and
bottom portions. The top and bottom socket portions may work
together to position the DUT for probing/contact to make electrical
connections to the test resources/instruments. In other words, the
loadboard and the socket may exchange test information with the DUT
during testing. For example, the loadboard and socket may use probe
contacts with the DUT to provide test signals for the DUT to
transmit to test antennas in the anechoic chamber. Similarly, the
loadboard and socket may use probe contacts with the DUT to receive
output from the DUT based on signals received by the DUT (e.g.,
transmitted from test antennas in the anechoic chamber).
[0087] The loadboard and/or socket(s) may include one or more
conductive pad (e.g., made of and/or plated with copper, gold
(e.g., hard gold plated), steel, and/or other electrically
conductive material). The conductive pad(s) may be electrically
coupled with a ground plane(s) (e.g., made of and/or plated with
copper, gold (e.g., hard gold plated), steel, and/or other
electrically conductive material). The ground plane may be a part
of the loadboard and/or may be external to the loadboard. For
example, a PCB may include a ground plane. For example, the
conductive pad may be (e.g., or may be mated to) a copper (e.g., or
other conductive) surface of the loadboard. The conductive pad may
be configured to electrically connect with a gasket interface of
the anechoic chamber, e.g., when the alignment fixture and the
DUT(s) are in the testing position. Thus, the combination of the
conductive pad(s), ground plane(s), and gaskets may isolate the
DUT(s) from electromagnetic interference (EMI) when the DUT(s) are
in the testing position. The ground plane may thus serve the
purpose of a "door" to be closed to provide EMI isolation. The
process of inserting a DUT and providing EMI isolation for the DUT
may be repeated for many cycles, e.g., many DUTs in automated
fashion. Reusing the ground plane of the loadboard to provide EMI
isolation may reduce cost and complexity.
[0088] In some embodiments, the alignment fixture may include an
attachment for the DUT(s). The attachment may accept the DUT(s) to
be inserted from the top down. The DUT(s) may be positioned at the
top of the chamber and the test antennas may be positioned at the
bottom of the chamber. Thus, for Tx testing, the DUT may radiate
signals down to the test antennas. With the inserted DUT (e.g.,
antenna array) facing down, the loadboard may be above the DUT.
This arrangement may facilitate easier integration with a (e.g.,
typical) handler, e.g., with no modifications (or minimal
modifications) to their standard mechanics which may be to pick up
and drop down. Further, the DUT facing down may facilitate easier
integration with an (e.g., typical) anechoic chamber, e.g., with
test antennas below (e.g., no movement of the RF test antennas may
be required). Other arrangements may be used as desired. For
example, the DUT may be positioned at the bottom or side of the
chamber.
[0089] FIG. 18 illustrates a blown-up view of an OTA alignment
fixture, according to some embodiments. As shown, the alignment
fixture may include a handler bracket 1802, e.g., a plunger. The
handler bracket 1802 may attach to a loadboard 1804. A DUT 1806 may
be placed between the loadboard 1804 and a chamber interface plate
1810. The chamber interface plate 1810 may be attached using one or
more shoulder screws 1808 to chamber interface gasket 1812. The
alignment fixture may position the DUT 1806 relative to chamber
1814. It will be appreciated that any number of additional chambers
1816 and corresponding OTA alignment fixtures may also be included
in an OTA test system.
[0090] The chamber interface plate 1810 may be fixed (e.g., in a
single position relative to the anechoic chamber 1814) or floating
(e.g., allowing controlled sliding motion relative to the chamber
1814). A floating chamber interface plate may be free to move
within a particular range (e.g., limited by alignment slots,
positioning pins, tracks, rails, and/or similar mechanisms). A
level of friction for such controlled motion may be configured as
desired, according to some embodiments. A chamber interface plate
may be referred to as a guideplate.
[0091] FIG. 19 illustrates a chamber interface plate 1810 and a
chamber 1814, according to some embodiments. In some embodiments,
the chamber interface plate 1810 may include a socket 1904. The
socket 1904 may have very stringent alignment tolerances. In some
embodiments, the socket 1904 may include two portions, e.g., a top
portion and a bottom portion. The top portion of the socket may
attach to a loadboard (not shown in FIG. 19). Thus, alignment of
the socket 1904 relative to the chamber 1814 may require some
coordination and/or adjustment of the chamber interface plate 1810.
The chamber 1814 may include one or more positioning pins 1905 and
the chamber interface plate 1810 may include one or more alignment
slots 1906, e.g., so that each alignment slot corresponds to a
positioning pin. Further, the chamber interface plate 1810 may be
made of (e.g., and/or coated with) low-friction material so that it
can shift a small amount to the desired location, e.g., to position
the DUT in the testing position. Similarly, the loadboard may have
guide pins that determine the (e.g., approximate) position of the
chamber interface plate (e.g., using additional alignment slots
1906). This way, when the handler (e.g., a plunger) brings a DUT
into the approximate testing position, the chamber interface plate
may move to the right location. This movement may be controlled by
a (e.g., customized) level of friction.
[0092] In some embodiments, the chamber interface plate may be
secured in place (e.g., using the screw and spring assembly 1908)
to avoid any vibration which may cause the chamber interface plate
to move out of place. The chamber interface plate force for
alignment may be balanced with the handler grip force on the DUT.
If the chamber interface plate moves too easily it may move due to
vibration, e.g., of moving arms of the handler. If the chamber
interface plate is too restrained, the handler grip force on the
DUT may be incapable of holding the DUT all the way into the socket
position. Thus, the force for alignment of the chamber interface
plate may be controlled by springs and screws 1908. The design may
allow for customized spring force to be added so that a desired
level of sliding friction between the chamber interface plate 1810
and the chamber 1814 may be achieved. The friction (e.g., spring
applied and/or due to weight of the chamber interface plate 1810
and/or other components) may allow the chamber interface plate to
move and align with the loadboard. When the DUT is placed, the
friction may restrict motion of the chamber interface plate such
that the DUT will glide into place either through gravity or
through sliding movement of the plunger holding the DUT as the DUT
descends into the socket. For example, the screws of the screw and
spring assembly 1908 may be tightened to increase the spring force
(and thus increase the level of sliding friction) to hold the
chamber interface plate in place more securely. Alternatively, the
screws may be loosened to decrease the spring force (and thus
friction) to allow the chamber interface plate to move more with
the handler, e.g., so that the handler may retain the DUT fully in
the socket. Further the spring k-value (e.g., stiffness of the
spring) may be customized to apply the proper friction force.
[0093] In some embodiments, a handler may rigidly hold the
loadboard. The chamber interface plate may allow a handler locating
pin (e.g., or pins, which may be located on the loadboard) to
determine its precise position (e.g., within 50 um, among various
possibilities). When the DUT is placed in the chamber interface
plate, the loadboard socket probe pins (e.g., RF probes) may
precisely locate to the DUT contact locations.
[0094] It will be appreciated that the spring(s) may be an optional
feature used to reduce or increase friction, if desired. In some
embodiments, the mass of the chamber interface plate may be massive
enough relative to the DUT mass that a spring may not be necessary.
In some embodiments, other sources of force (e.g., instead of or in
addition to) spring force may be used to control the level of
friction. For example, weights, magnets, clips, or different types
of materials may be used.
[0095] The chamber interface plate 1810 may change (e.g., may be
exchanged) based on characteristics of the DUT(s) to be tested. For
example, if there are bigger DUTs to be tested, a different chamber
interface plate 1810 may be used. For a relatively small DUT like
the one shown, a relatively large chamber interface plate 1810 may
be used and the chamber interface plate may be relatively small,
e.g., because the material of the chamber interface plate is more
expensive and fragile.
[0096] One or more detection mechanisms, e.g., illustrated as a
pair (1912 and 1913) may be used to detect the DUT placement,
according to some embodiments.
[0097] FIG. 20 illustrates aspects of EMI isolation of a DUT by the
alignment fixture in combination with an RF gasket 1812 of the
anechoic chamber, according to some embodiments. In some
embodiments, multiple DUTs may be tested in parallel in the same
system (e.g., simultaneously, in the same or separate anechoic
chambers). Thus, EMI isolation may be important to make sure there
is no interference from one DUT or tester to the next.
[0098] The isolation may be done using the loadboard. The loadboard
may include a ground plane to provide the electromagnetic
compatibility (EMC), e.g., via EMI isolation. In some embodiments,
an EMI seal may be achieved by adding a conductive pad 2004 to the
loadboard that connects the ground plane. This conductive pad may
make contact with a gasket interface 1812 on the anechoic chamber
to provide full EMC, e.g., when the load board is in contact with
the chamber interface so that the DUT(s) may be in the testing
position.
[0099] In some embodiments, the design of the conductive pad 2004,
ground plane, and gasket 1812 may last a long time and may be
produced out of common materials (e.g., the socket and the chamber
interface plate may not be made of any exotic RF shielding
materials). In some embodiments, the isolation may be close to -40
dB which may be sufficient for testing at frequencies 24 GHz and
above. In some embodiments, the design may also be relatively low
cost, e.g., due to reducing the number of shielding interfaces and
using PCB technology instead of additional mechanical parts.
[0100] FIG. 21 illustrates a loadboard 1804 being compressed
between a handler interface bracket 1802 and an anechoic chamber
1814. In some embodiments, the handler (e.g., plunger) may press
with different pressures, e.g., depending on requirements, e.g.,
different types of DUTs may be tested with different amounts of
pressure. For example, the RF gasket contact pressure may be about
15 Kg of force, e.g., to achieve a good seal, e.g., for EMI
isolation. To spread the force, a bracket mounted above the
loadboard 1804 may transfer the force directly to the chamber 1814
structure, reducing PCB (e.g., loadboard 1804) deflection due to
the force of the gasket on the PCB (e.g., loadboard 1804). The
design may incorporate a level of rigidity to compress the
loadboard 1804 in a planar way and thus avoid or reduce errors over
time (e.g., due to bending or uneven wear of the loadboard). In
some embodiments, the design may support much more load than is
needed.
[0101] FIG. 22 illustrates how the alignment fixture may be adapted
to accommodate different types of DUTs, according to some
embodiments. The design of the alignment fixture may be in layers
to allow swapping one component individually while the other
components remain assembled. This layered design may help adapt
certain sections to other DUTs in an efficient way. For example, a
larger DUT may use a larger chamber interface plate or a different
socket, but it may keep the chamber interface plate 1810 the same.
As shown, the loadboard 2203 to handler 2205 interface may also
have a clearance 2204 to help populate the loadboard underneath,
e.g., allowing more space for components.
[0102] FIG. 23 illustrates an alignment fixture 2302, according to
some embodiments. As shown, the alignment fixture (e.g., the
components outlined by box 2302 as illustrated) may be an interface
between an anechoic chamber 2304 and a handler 2306. The handler
may move all or a portion of the alignment fixture to bring one or
more DUT to the anechoic chamber. The alignment fixture may connect
the DUT(s) to testing equipment (e.g., to provide signals for the
DUT(s) to transmit in Tx testing and/or to measure signals received
by the DUT(s) in Rx testing). Additionally, the alignment fixture
provide EMI isolation and mechanical alignment for the DUT(s)
during testing.
[0103] FIG. 24 is a simplified block diagram, illustrating an
exemplary method for performing production testing of DUTs such as
phase array antennas, e.g., mmW ICs. It is noted that the method of
FIG. 24 is merely one example of a possible method, and that
features of this disclosure may be implemented in any of various
methods, as desired. Aspects of the method of FIG. 24 may be
implemented by a system including an alignment fixture (or multiple
alignment fixtures), such as illustrated in and described with
respect to the Figures, among other systems and devices, as
desired. For example, the method of FIG. 24 may be implemented by a
systems and devices such as shown in FIGS. 17-23, among various
possibilities. In various embodiments, some of the elements of the
methods shown may be performed concurrently, in a different order
than shown, may be substituted for by other method elements, or may
be omitted. Additional method elements may also be performed as
desired. As shown, the method may operate as follows.
[0104] A level of (e.g., sliding) friction for a particular type of
DUT may be determined and the alignment fixture may be calibrated
to provide the determined level of friction (2410), according to
some embodiments. The level of friction may be determined so that a
sliding friction between the chamber interface plate and the
loadboard resists vibration and maintains the DUT in a testing
position. For example, the level of friction may be high enough so
that the chamber interface plate does not slide (e.g., more than a
threshold distance) relative to an anechoic chamber and the level
of friction may be low enough so that the DUT, when inserted,
remains in a socket. For example, if the level of friction is too
high, the DUT may be pulled out of the socket and/or damaged by
vibration.
[0105] In some embodiments, the level of friction may be set, e.g.,
using one or more springs which may be adjusted using screws or
other adjustment mechanisms. In some embodiments, the level of
friction may be determined and/or set automatically.
[0106] The alignment fixture may install the DUT(s) in a testing
position (2420), according to some embodiments. In the testing
position, the alignment fixture may provide for EMI isolation of
the DUT(s). Further, in the testing position, the alignment fixture
may provide the determined level of friction.
[0107] The alignment fixture may provide and/or receive signals
to/from the DUT(s) for OTA testing (2430), according to some
embodiments. The testing may include testing the beamforming
capability of the DUT(s) in transmitting and/or receiving
signals.
FIGS. 25-30--Example alignment fixtures
[0108] As noted above, an alignment fixture may consist of a number
of layers. FIGS. 25-30 illustrate various examples of the layering
and modular design of OTA test interfaces using alignment fixtures
as described herein. More specifically, FIGS. 25 and 26 illustrate
example, alternative means of providing shielding. FIGS. 27 and 28
illustrate example, alternative means of providing alignment. FIGS.
29 and 30 illustrate example, alternative socket locations. It will
be appreciated that these alternatives are independent and may be
mixed and matched as desired. For example, the shielding approach
of FIG. 27 may combined with the alignment approach of either FIG.
27 or 28 and may further be combined with the socket locations of
either FIG. 29 or 30, etc. It will be appreciated that FIGS. 25-30
may be expanded views, e.g., in the illustrations, empty space may
be shown between one or more layers, but the layers may be in
contact, according to some embodiments.
[0109] FIG. 25 illustrates an alignment fixture with an
electromagnetic (EM) shield separate from a loadboard, according to
some embodiments. As shown, a handler plunger may connect to a
handler interface bracket 1802. The bracket 1802 may connect to an
EM shield 2503. The EM shield 2503 may be distinct from the
loadboard 1804. For example, the EM shield 2503 may be a conductive
material (e.g., copper or other metal, etc.) and may be configured
to contact to a gasket for EM shielding 1812. Thus, the EM shield
2503 and the gasket 1812 may provide EM shielding for a DUT in the
testing position. For example, the handler plunger may move down
(e.g., in the orientation of the Figure; other orientations may be
used as desired), pressing the EM shield 2503 against the gasket
1812. In other words, the conductive shield 2503 may surround
(e.g., partly, as shown) the loadboard 1804 and may seal to the
anechoic chamber 1814. When in contact, the shield 2503 and gasket
1812 may provide shielding for the DUT so that the DUT may provide
for EM isolation and thus EMC of the DUT during testing. Thus, the
DUT may be isolated from EM interference from outside of the
chamber 1814.
[0110] The alignment fixture may further include a socket 1904. As
shown, the socket may be divided into two parts/portions, e.g.,
referred to as a top socket and bottom socket. The bottom socket
may be connected to the chamber 1814 via a chamber interface plate
1810.
[0111] It will be appreciated that the gasket 1812 and the shield
2503 may each go all the way around the socket 1904. For example,
the gasket 1812 and the shield 2503 may create a perimeter around
the socket 1904.
[0112] FIG. 26 illustrates an alignment fixture providing shielding
using a groundplane of the loadboard 1804 and a conductive pad 2004
to provide shielding, e.g., instead of the separate EM shield 2503,
according to some embodiments. The conductive pad 2004 may have a
continuous connection to the groundplane of the loadboard, e.g.,
all the way around the loadboard so that the socket 1904 is
surrounded. As shown, a conductive pad 2004 may be configured to
contact the gasket 1812 and create EM isolation for the DUT when
the DUT is in the testing position (e.g., in a similar manner as
described above regarding the shield 2503 of FIG. 25). Thus, the
groundplate, e.g., in combination with the conductive pad 2004 and
the gasket 1812, may be an EM shield for the DUT.
[0113] FIG. 27 illustrates an alignment fixture incorporating a
chamber interface plate 1810, according to some embodiments. The
chamber interface plate 1810 may be a floating plate (e.g., not
rigidly attached to the chamber 1814) that may be able to slide in
at least one dimension. For example, the chamber interface plate
1810 may be free to move in the horizontal plane (e.g., as
indicated in the figure by the Y motion and X motion arrows). Thus,
the chamber interface plate may control motion (e.g., of the bottom
socket and thus of a DUT in the testing position) in the X and Y
dimensions. In some embodiments, the motion of the chamber
interface plate 1810 may be perpendicular to the motion of the
handler (e.g., to bring a DUT into the testing position, e.g., as
indicated in the figure by the Z motion arrow). Moreover, the at
least one dimension in which the chamber interface plate is free to
move may be in the parallel to the plane of an opening in the
anechoic chamber (e.g., which is horizontal, in the illustrated
example). Thus, the motion of the chamber interface plate may align
the DUT with the opening (e.g., in the center of the opening).
[0114] The level of friction between the chamber interface plate
and the chamber may be configured as desired, e.g., as discussed
above. For example, the weight of the chamber interface plate and
the bottom socket may be designed or adjusted to provide a desired
level of friction or the level of friction may be controlled by one
or more springs, among various possibilities.
[0115] FIG. 28 illustrates an alignment fixture with a handler
interface bracket 1802 configured to control motion in at least one
dimension, according to some embodiments. For example, the handler
interface bracket 1802 may include a sliding mechanism to control
motion in the horizontal plane (e.g., X and Y dimensions, as
shown). The chamber interface plate 1810 may be fixed to the
chamber (e.g., may not be floating or sliding). In some
embodiments, both a sliding chamber interface plate 1810 and a
sliding mechanism in the handler interface bracket 1802 may be
used.
[0116] FIG. 29 illustrates an alignment fixture with a bottom
socket 1904 mounted to a chamber interface plate 1810, according to
some embodiments. For example, the bottom socket 1904 may position
the DUT (e.g., relative to the chamber interface plate 1810) and
may (e.g., in combination with the top socket) provide
probe/electrical connections between the DUT and test resources or
instruments (e.g., via the loadboard). Note that, in the
illustrated example, a fixed chamber interface plate 1810 is shown,
but a floating chamber interface plate 1810 may be used as
desired.
[0117] FIG. 30 illustrates an alignment fixture without a bottom
socket and the functions of the bottom socket provided by a chamber
interface plate with an integrated bottom socket 3002, according to
some embodiments. For example, the chamber interface plate with an
integrated bottom socket 3002 may incorporate one or more brackets
or other attachment mechanisms for positioning the DUT relative to
the chamber interface plate with an integrated bottom socket 3002
and positioning the DUT for probe/electrical connections. The
chamber interface plate with an integrated bottom socket 3002 may
be fixed or floating.
[0118] As noted above, aspects of the FIGS. 25-30 may be used in
various combinations as desired. For example, although FIGS. 27-30
show conductive pad 2004 rather than EM shield 2503, other features
of FIGS. 27-30 may be used with an EM shield 2503. For example, an
EM shield 2503 may be used with a chamber interface plate 1810,
etc. Similarly, a chamber interface plate with an integrated bottom
socket 3002 may be used with a EM shield 2503. As another example
combination, a chamber interface plate 1810 as illustrated in FIG.
27 may be used in combination with a handler interface bracket 1802
including a sliding mechanism as illustrated in FIG. 28. Numerous
other combinations and variations are possible.
Additional Information
[0119] In some embodiments, the OTA test apparatus may be
configured so that the loadboard does not wipe across the gasket
when aligning the DUT in the testing position. By avoiding such
wiping, premature wear of the loadboard and/or gasket.
[0120] In some embodiments, an interface to the anechoic chamber
(e.g., chamber interface plate) may be able to provide several
features in a cost-effective single part. For example, a plastic
interface may have a higher wear interface than the electrically
conductive interfaces. The interface may be RF transparent plastic.
The plastic material may be able to allow freedom for the chamber
interface plate to slide into alignment position, e.g., without
using more expensive solution. For example, mechanical solutions,
such as mechanical slide rails or bearings may not be used,
according to some embodiments.
[0121] In some embodiments, the OTA testing may performed in the
near field, transition zone, and/or far field regions.
[0122] In some embodiments, OTA testing may include measuring
transmit and/or receive parameters such as power, frequency, phase,
modulation quality, spectrum occupancy, sensitivity, selectivity,
image rejection, spurious responses, blocking, etc. using an array
of testing antennas. Performance as a function of distance from the
DUT may represented by a bathtub curve (e.g., in Tx testing, too
close to the DUT, a test antenna may be overloaded; too far from
the DUT, the strength of signal from the DUT may be small relative
to noise/interference). The bathtub curve may also apply in Rx
testing.
[0123] In some embodiments, during Tx testing, signals from
multiple elements of the array of testing antennas may be combined,
e.g., using a beamforming algorithm, and the combined signal may be
tested. In some embodiments, individual signals from individual
antennas may be tested individually.
[0124] In some embodiments, the testing may be performed
automatically, e.g., in response to placement of the DUT in the
system and connection to the power/control connections.
[0125] In some embodiments, multiple DUTs may be tested. For
example, multiple DUTs may be installed in testing positions, and
may be concurrently or sequentially tested.
[0126] In some embodiments, the DUT's wireless capabilities may be
tested for phase, power, spectrum, frequency, and/or modulation.
Such capabilities may be tested in transmission and/or
reception.
[0127] In the following, exemplary embodiments are provided.
[0128] In one set of embodiments, an over-the-air (OTA) test
apparatus, may comprise: a gasket interface; and a loadboard. The
loadboard may comprise: an attachment for a device-under-test
(DUT); a ground plane; and a conductive pad, wherein the conductive
pad is configured to contact the gasket interface and electrically
connect the gasket interface with the ground plane when the
loadboard is in a testing position, wherein the ground plane, the
gasket interface, and the conductive pad provide electromagnetic
isolation for the DUT in the testing position.
[0129] In some embodiments, the attachment for the DUT may be
configured so that a DUT may be inserted from the top down.
[0130] In some embodiments, the loadboard may further comprise one
or more positioning pin and the attachment for the DUT may
comprise: a guideplate comprising one or more alignment slot for
positioning the guideplate relative to the loadboard using the one
or more positioning pin.
[0131] In some embodiments, the OTA test apparatus may further
comprise a spring, wherein the spring produces a force on the
guideplate so that a sliding friction between the guideplate and
the loadboard resists vibration and maintains the DUT in a testing
position.
[0132] In some embodiments, the guideplate is a low-friction
guideplate.
[0133] A further exemplary set of embodiments may include a
non-transitory computer accessible memory medium comprising program
instructions which, when executed at a device, cause the device to
implement any or all parts of any of the preceding examples.
[0134] A still further exemplary set of embodiments may include a
computer program comprising instructions for performing any or all
parts of any of the preceding examples.
[0135] Yet another exemplary set of embodiments may include an
apparatus comprising means for performing any or all of the
elements of any of the preceding examples.
[0136] Although the embodiments above have been described in
considerable detail, numerous variations and modifications will
become apparent to those skilled in the art once the above
disclosure is fully appreciated. It is intended that the following
claims be interpreted to embrace all such variations and
modifications.
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