U.S. patent application number 14/502363 was filed with the patent office on 2016-03-31 for input/output termination for ripple prevention.
The applicant listed for this patent is Analog Devices Global. Invention is credited to Yusuf Alperen Atesal, Turusan Kolcuoglu.
Application Number | 20160093579 14/502363 |
Document ID | / |
Family ID | 53887040 |
Filed Date | 2016-03-31 |
United States Patent
Application |
20160093579 |
Kind Code |
A1 |
Atesal; Yusuf Alperen ; et
al. |
March 31, 2016 |
INPUT/OUTPUT TERMINATION FOR RIPPLE PREVENTION
Abstract
Aspects of this disclosure relate to a termination circuit
configured to mitigate crosstalk from a radio frequency (RF)
input/output (I/O) path to a second I/O path, such as a digital I/O
path. Such crosstalk can be due to coupling between adjacent bond
wires, for example. The termination circuit can include a low
impedance loss path, such as a series RC shunt circuit. According
to certain embodiments, an electrostatic discharge (ESD) protection
circuit can be in parallel with the termination circuit.
Inventors: |
Atesal; Yusuf Alperen;
(Istanbul, TR) ; Kolcuoglu; Turusan; (Istanbul,
TR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Analog Devices Global |
Hamilton |
|
BM |
|
|
Family ID: |
53887040 |
Appl. No.: |
14/502363 |
Filed: |
September 30, 2014 |
Current U.S.
Class: |
361/56 |
Current CPC
Class: |
H01L 2224/45014
20130101; H01L 2924/206 20130101; H01L 2224/45015 20130101; H01L
2224/45099 20130101; H01L 2924/207 20130101; H01L 2224/05599
20130101; H01L 2224/05554 20130101; H01L 23/64 20130101; H04B 3/32
20130101; H01L 2224/05553 20130101; H01L 2924/1205 20130101; H01L
2924/00014 20130101; H01L 2924/00014 20130101; H01L 2924/00014
20130101; H01L 23/642 20130101; H01L 2924/1207 20130101; H01L 24/48
20130101; H01L 2924/00014 20130101; H01L 2924/00014 20130101; H01L
2924/1421 20130101; H01L 2224/45014 20130101; H01L 23/60 20130101;
H01L 27/0248 20130101; H01L 2224/49171 20130101; H01L 2223/6611
20130101; H01L 2224/48227 20130101; H01L 24/49 20130101; H01L 23/66
20130101; H01L 23/647 20130101; H01L 23/50 20130101 |
International
Class: |
H01L 23/66 20060101
H01L023/66; H01L 27/02 20060101 H01L027/02; H04B 3/32 20060101
H04B003/32; H01L 23/60 20060101 H01L023/60; H01L 23/64 20060101
H01L023/64; H01L 23/00 20060101 H01L023/00; H01L 23/50 20060101
H01L023/50 |
Claims
1. An electronic device comprising: a die comprising a radio
frequency (RF) input/output path electrically connected to a first
bond pad of the die and a second input/output path electrically
connected to a second bond pad of the die, the RF input/output path
configured to process an RF signal, and the second I/O path
configured to process a second signal, the second signal being a
non-RF signal; a first bond wire electrically connected to the
first bond pad of the die; and a second bond wire electrically
connected to the second bond pad of the die; and a termination
circuit electrically connected to the second bond pad of the die,
the termination circuit configured to mitigate against effects of
crosstalk due to coupling between the first bond wire and the
second bond wire by providing a load for the second I/O path such
that the second I/O path is dampened.
2. The electronic device of claim 1, wherein the die comprises an
electrostatic device protection circuit in parallel with the
termination circuit.
3. The electronic device of claim 1, wherein the termination
circuit is embodied in the die.
4. The electronic device of claim 1, wherein the termination
circuit comprises a series RC circuit.
5. The electronic device of claim 1, wherein the second
input/output path is a digital input/output path and the second
signal is a digital signal.
6. The electronic device of claim 1, wherein the termination
circuit is configured to prevent a load on the die that is
electrically connected to the second bond pad from resonating due
to the crosstalk.
7. The electronic device of claim 1, further comprising a package
encapsulating the die, the first bond wire, and the second bond
wire, wherein the package comprises a first pin and the first bond
wire is electrically connected to the first pin.
8. The electronic device of claim 1, wherein the die comprises at
least one of an attenuator, a switch, or a phase shifter.
9. An apparatus comprising: a first input/output path electrically
connected to a first contact of a die, the first input/output path
configured to carry a radio frequency signal; a second input/output
path electrically connected to a second contact of the die, the
second input/output path configured to carry a second signal,
wherein the second signal is a non-RF signal, and wherein there is
crosstalk between the first input/output path and the second
input/output path; and an RC circuit electrically connected between
the second contact of the die and a reference potential.
10. The apparatus of claim 9, further comprising an electrostatic
discharge protection circuit on the die, wherein the RC circuit is
in parallel with the electrostatic discharge protection
circuit.
11. The apparatus of claim 9, wherein the second signal is a
digital signal.
12. The apparatus of claim 9, further comprising a first bond wire
electrically connected to the first contact of the die and a second
bond wire electrically connected to the second contact of the die,
wherein the first input/output path is configured to couple with
the second input/output path by way of coupling between the first
bond wire and the second bond wire.
13. The apparatus of claim 9, wherein the RC circuit is a series RC
circuit.
14. The apparatus of claim 9, wherein the RC circuit is configured
to prevent an effective capacitance of a load of the die
electrically connected to the second input/output path from
resonating due to crosstalk between the first input/output path and
the second input/output path.
15. The apparatus of claim 14, wherein the load comprises an
electrostatic discharge protection circuit and an input/output
buffer.
16. The apparatus of claim 14, wherein the crosstalk is due to
coupling external to the die.
17. The apparatus of claim 9, wherein the reference potential is
ground.
18. A die comprising: a first input/output path configured to carry
a radio frequency signal; a second input/output path configured to
carry a non-RF signal; an electrostatic discharge protection
circuit configured to provide electrostatic discharge protection on
the second input/output path; and a low impedance loss path
configured to present an impedance at a frequency of the radio
frequency signal to prevent a resonance on the second input/output
path due to crosstalk between the first input/output line and the
second input/output line.
19. The die of claim 18, wherein the crosstalk is due to coupling
on the die.
20. The die of claim 18, wherein the low impedance loss path
comprises a series RC circuit.
Description
TECHNICAL FIELD
[0001] The disclosed technology relates to electronics, and, more
particularly, to a termination circuit electrically connected to an
input/output.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0002] Electronic devices are being manufactured with increasingly
smaller sizes. For instance, wideband control products, such as
switches and attenuators, are being widely used in various
applications, such as transceivers, sources, analyzers, etc. In
these applications, minimizing die and package size while
minimizing performance changes over bandwidth, such as changes in
gain and/or loss over bandwidth, can be desirable. At the same
time, it can be desirable to have a relatively high electrostatic
discharge (ESD) protection level.
[0003] Such control products can include multiple digital
input/output (I/O) pins and multiple radio frequency (RF) I/O pins
in a relatively small area. As one example, a serial peripheral
interface (SPI) controlled digital attenuator can be implemented in
a 4 mm.times.4 mm quad flat no-leads (QFN) package. Crosstalk
inside the package from an RF input (and/or an RF output) can
result in undesired effects that can cause changes in performance
over bandwidth. This can limit operational bandwidth of a product
and/or deteriorate circuit performance, such as attenuation
accuracy of an attenuator.
SUMMARY OF CERTAIN INVENTIVE ASPECTS
[0004] One aspect of this disclosure is an electronic device that
includes a die, a first bond wire, a second bond wire, and a
termination circuit. The die includes a radio frequency (RF)
input/output path electrically connected to a first bond pad of the
die and a second input/output path electrically connected to a
second bond pad of the die. The RF input/output path is configured
to process an RF signal. The second I/O path is configured to
process a non-RF signal (a signal that is not an RF signal). The
first bond wire is electrically connected to the first bond pad of
the die. The second bond wire is electrically connected to the
second bond pad of the die. The termination circuit is electrically
connected to the second bond pad of the die. The termination
circuit is configured to mitigate effects of crosstalk due to
coupling between the first bond wire and the second bond wire by
providing a load for the second I/O path such that the second I/O
path is dampened.
[0005] The die can include an electrostatic device protection
circuit in parallel with the termination circuit. The die can also
include at least one of an attenuator, a switch, or a phase
shifter. The electronic device can include a package encapsulating
the die, the first bond wire, and the second bond wire, in which
the package includes a first pin and the first bond wire is
electrically connected to the first pin.
[0006] The termination circuit can be embodied on the die. The
termination circuit can include a series RC circuit. The
termination circuit can be configured to prevent a load on the die
that is electrically connected to the second bond pad from
resonating due to the crosstalk.
[0007] The second input/output path can be a digital input/output
path and the second signal can be a digital signal.
[0008] Another aspect of this disclosure is an apparatus that
includes a first input/output, a second input/output path, and an
RC circuit. The first input/output path is electrically connected
to a first contact of a die. The first input/output path is
configured to carry a radio frequency signal. The second
input/output path is electrically connected to a second contact of
the die. The second input/output path is configured to carry a
non-RF signal. In the apparatus, there is crosstalk between the
first input/output path and the second input/output path. The RC
circuit electrically is connected between the second contact of the
die and a reference potential.
[0009] The apparatus can include an electrostatic discharge
protection circuit in the die, in which the RC circuit is in
parallel with the electrostatic discharge protection circuit. The
second signal can be a digital signal. The reference potential can
be ground.
[0010] The apparatus can include a first bond wire electrically
connected to the first contact of the die and a second bond wire
electrically connected to the second contact of the die, in which
the first input/output path is configured to couple with the second
input/output path by way of coupling between the first bond wire
and the second bond wire.
[0011] The RC circuit can be a series RC circuit. The RC circuit
can be configured to prevent an effective capacitance of a load of
the die electrically connected to the second input/output path from
resonating due to crosstalk between the first input/output path and
the second input/output path. The load can include an electrostatic
discharge protection circuit and an input/output buffer. The
crosstalk can be due to coupling external to the die.
[0012] Another aspect of this disclosure is a die that includes a
first input/output path, a second input/output path, an
electrostatic discharge protection circuit, and a low impedance
loss path. The first input/output path is configured to carry a
radio frequency signal. The second input/output path is configured
to carry a non-RF signal. The electrostatic discharge protection
circuit is configured to provide electrostatic discharge protection
on the second input/output path. The low impedance loss path is
configured to present an impedance at a frequency of the radio
frequency signal to prevent a resonance on the second input/output
path due to crosstalk between the first input/output line and the
second input/output line.
[0013] The low impedance loss path can include a series RC circuit.
The crosstalk can be due to coupling on the die.
[0014] For purposes of summarizing the disclosure, certain aspects,
advantages and novel features of the inventions have been described
herein. It is to be understood that not necessarily all such
advantages may be achieved in accordance with any particular
embodiment of the invention. Thus, the invention may be embodied or
carried out in a manner that achieves or optimizes one advantage or
group of advantages as taught herein without necessarily achieving
other advantages as may be taught or suggested herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These drawings and the associated description herein are
provided to illustrate specific embodiments and are not intended to
be limiting.
[0016] FIG. 1 is a plan view schematic diagram of a portion of a
packaged device, according to an embodiment.
[0017] FIGS. 2A, 2B, and 2C are a schematic diagrams that each
include an input/outline line that experiences radio frequency
current due to crosstalk and a termination circuit electrically
connected to the input/output line, according to certain
embodiments. FIGS. 2A, 2B, and 2C each illustrate a different
termination circuit.
[0018] FIG. 3 is a schematic diagram of a die that includes a radio
frequency input/output line and another input/output line that is
electrically connected to a termination circuit, according to an
embodiment.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0019] The following detailed description of certain embodiments
presents various descriptions of specific embodiments. However, the
innovations described herein can be embodied in a multitude of
different ways, for example, as defined and covered by the claims.
In this description, reference is made to the drawings where like
reference numerals may indicate identical or functionally similar
elements. It will be understood that elements illustrated in the
figures are not necessarily drawn to scale.
[0020] As discussed above, an RF input/output can cause crosstalk
on an another input/output within a package. As used herein,
"input/output" encompasses an input, an output, or a combined input
and output. Accordingly, any features discuss herein related to an
"input/output" can be applied to an input, to an output, or to a
combined input and output. An "input/output" is equivalently
referred to as an "I/O" herein. Crosstalk from the RF input/output
can result in an undesired effect that can cause a change in
performance over bandwidth. For instance, the crosstalk inside the
package from an RF input/output to a digital input/output can
resonate with a load electrically connected to the digital
input/output on a die, such as a semiconductor die. This can result
in an unwanted and/or unexpected resonance, which can create a low
or high impedance RF path at and/or near resonance, and hence can
in turn cause fluctuations (e.g., ripples) in the gain and/or loss
frequency response of a device that includes the die. Such
fluctuations can reduce the operation bandwidth of the device
and/or deteriorate device performance, such as attenuation accuracy
of an attenuator.
[0021] Introducing a ground shield (e.g., a ground pin on a package
of the device, a ground pad on the die, and a ground bond wire)
between a digital input/output and an RF input/output can reduce
crosstalk between the digital input/output and the RF input/output.
Alternatively or additionally, having perpendicular bond wire
placements can reduce crosstalk. However, these ways of reducing
crosstalk can increase package and/or die size significantly.
Accordingly, they may not be practical for relatively small sized,
multi-pin devices. A termination method that can prevent resonances
due to crosstalk between an RF input/output and another non-RF
input/output while maintaining circuit performance and/or ESD
protection levels can be desirable, particularly if such a method
were implemented with no more than a relatively small impact on
area of the die and the package.
[0022] Fluctuations in a frequency response of a circuit can be due
to a resonance of the capacitive loading of a digital I/O pad of an
integrated circuit die and the crosstalk between an RF I/O bond
wire and a digital I/O bond wire. In certain applications, the
capacitive load on an integrated circuit die pad can be dominated
by the capacitance of an ESD protection circuit and an input/output
buffer, especially for applications that desire greater than about
1000 kV of ESD protection. RF current coupled from RF bond wires to
digital I/O bond pads can create high Q RF resonances. A high Q RF
resonance can refer to an RF resonance with Q being at least 50,
for example.
[0023] Electrically connecting a loss component, such as a
resistor, in series between a digital I/O pad and an ESD protection
circuit on die can reduce the resonances that result from crosstalk
with an RF input/output. However, such a loss component can
significantly reduce the ESD rating and/or have a relatively large
size.
[0024] Aspects of this disclosure relate to a loss path in parallel
with an ESD protection circuit and/or input/output buffers. The
loss path can present a lower impedance than the load at the
operating frequency range of the load. Accordingly, in certain
applications, the loss path can reduce or eliminate the resonances
and also preserve substantially the same ESD rating. The loss path
can be, for example, a series RC shunt circuit electrically
connected to an I/O on a die.
[0025] Referring to FIG. 1, a portion of an electronic device 1
will be described. The electronic device 1 is a packaged device.
The electronic device includes a package 10 and a die 12 that is
encapsulated by the package 10. It will be understood that the
electronic device 1 can include more elements than illustrated
and/or that some embodiments include a subset of the illustrated
elements. For instance, only a portion of the die 12 is
illustrated. Other portions of the die (not illustrated) can
include a variety of other circuits, such as an attenuator, an
amplifier, a mixer, a switching component such as a multi-throw
switch, a phase shifter, or any other suitable circuits configured
to process RF and/or digital signals. The other circuits can be
control circuits. In some instances, one or more digital signals
can be used as control signals for a circuit that processes an RF
signal. Moreover, while the digital I/O lines are illustrated as
being digital inputs in FIG. 1, it will be understood that the
principles and advantages discussed with reference to FIG. 1 can be
applied to digital outputs or combined digital inputs and outputs.
In some other embodiments, the principles and advantages discussed
with reference to FIG. 1 can be applied to non-RF analog inputs
and/or outputs or combined digital and/or analog inputs and/or
outputs.
[0026] The illustrated package 10 includes pins 14a to 14g. As
illustrated, the package 10 is a quad-flat no-lead (QFN) package.
It will be understood that the principles and advantages discussed
herein can be applied to any other suitable type of package and
contact. For example, other types of contacts can include, but are
not limited to, sockets, balls, and lands. The package 10 can
include a carrier substrate on which the die 12 is mounted. Each of
the pins 14a to 14g of the package 10 is electrically connected to
the die 12 by way of a respective bond wire 16a to 16g in FIG.
1.
[0027] The die 12 can be a silicon die as illustrated. In certain
embodiments, the die 12 is a silicon-on-insulator die or other
semiconductor die. The die 12 can alternatively be any other
suitable type of die that can benefit from ripple prevention on an
I/O. The illustrated die 12 includes die pads 18a to 18g that are
electrically connected to respective pins 14a to 14g by way of
respective bond wires 16a to 16g. Any suitable number of pins, bond
wires, and die pads can be implemented in the electronic device 1.
A bond wire can also be referred to as a wirebond or a ribbon-bond.
In the embodiment of FIG. 1, the die 12 includes RF I/Os and
digital I/Os. Die pads 18a, 18c, 18d, 18e, and 18g are configured
to receive digital signals and die pads 18b and 18f are configured
to receive RF signals.
[0028] Digital I/O lines 20a, 20c, 20d, 20e, and 20g are configured
to carry digital signals. These digital I/O lines can provide
digital signals to digital circuits for further processing. The
digital I/O line 20a electrically connects the die pad 18a to a
termination circuit 22a and a load that includes ESD protection
circuit 24a and buffer 26a. While the load can include other
circuit elements, an effective capacitance of the load can be
dominated by capacitance from the ESD protection circuit 24a and
the buffer 26a in certain applications. The termination circuit 22a
can provide termination for RF signals that result from crosstalk
from an adjacent RF I/O line. For instance, crosstalk can result
from coupling between the bond wire 16b and the bond wire 16a. More
details regarding the termination circuit 22a and some sources of
crosstalk will be provided with reference to FIGS. 2A, 2B, 2C and
3. Any of the termination circuits shown in FIG. 1 can implement
any suitable combination of features of any of the termination
circuits discussed herein, such as the termination circuits of
FIGS. 2A, 2B, 2C, or 3. The ESD protection circuit 24a can be any
circuit that provides suitable ESD protection for a particular
application. In some instances, the ESD protection circuit 24a can
be rated to provide at least about 500 V of ESD protection, at
least about 1 kV of ESD protection, or at least about 4 kV of ESD
protection. The buffer 26a can buffer the digital signal carried by
the digital I/O line 20a and provide the buffered digital signal to
other circuit elements of the die 12. For instance, the buffered
digital signal can be provided to digital circuits on the die 12
for further processing. The buffer 26a can be implemented by one or
more inverters. The buffer 26a can be a non-inverting buffer. In
some instances, the buffer 26a can be an inverting buffer that
outputs a signal that is inverted relative to the digital signal
received by the buffer 26a. Such an inverting buffer can be
implemented by an odd number of inverters.
[0029] Other digital I/O lines and associated circuitry can
implement any combination of features discussed with reference to
the digital I/O line 20a and its associated circuitry. For
instance, all of the digital I/O lines and associated circuits
illustrated in FIG. 1 include instantiations of the same elements.
As shown in FIG. 1, digital I/O lines that are not adjacent to an
RF I/O can include a termination circuit. In some other
implementations, digital I/O lines that are not adjacent to an RF
I/O may omit a termination circuit.
[0030] Referring to FIG. 2A, a schematic diagram that includes an
I/O that experiences radio frequency current due to crosstalk and a
termination circuit electrically connected to the I/O will be
described. FIG. 2A illustrates a portion of the electronic device 1
of FIG. 1. In FIG. 2A, a digital I/O path is physically close to an
RF I/O path. For instance, the digital I/O path can include a bond
wire that is routed adjacent to a bond wire of the RF I/O path.
Bond pads associated with the digital I/O and the RF I/O,
respectively, can be adjacent to each other on a die. While FIG. 2A
shows a termination circuit electrically connected to a digital I/O
line for illustrative purposes, the principles and advantages
discussed with reference to any of the embodiments herein can be
applied in connection with a termination circuit for preventing
ripples on any suitable non-RF I/O path configured to carry a
non-RF signal. Such a non-RF I/O path can be configured to carry a
digital signal and/or an analog signal outside of the RF range.
[0031] A digital I/O on an integrated circuit die can be
electrically connected to an ESD protection circuit 24a and an I/O
buffer 26a as illustrated in FIG. 2A. A digital I/O path can carry
a digital signal that is a non-RF signal. The ESD protection
circuit 24a and the I/O buffer 26a can present an effective high Q
capacitance to the digital I/O path. Without the termination
circuit 22a, an RF current can undesirably be introduced on the
digital I/O path due to crosstalk. Inductance from the coupling
between the RF I/O bond wire 16b and the digital I/O bond wire 16a
can resonate with the effective capacitance on the digital bond pad
18a of the die without a proper termination circuit on the digital
I/O path. The coupling can be inductive coupling. The effective
capacitance on the digital bond pad 18a of the die can be dominated
by the ESD protection circuit 24a and the I/O buffer 26a.
[0032] In an illustrative example, a digital attenuator can be
included in the die 12 to provide up to about 30 dB of attenuation
for the RF I/O, and the digital attenuator can be controlled by one
or more signals carried on the digital I/O. In this example, a
resonance on the digital I/O path can create a relatively sharp
loss of power over frequency for the RF I/O path and would be
desirably avoided or dampened. Such resonance can create ripples in
the attenuation frequency response. In general, resonance from the
load on the digital I/O can create notches and/or overshoots in a
frequency response of a circuit electrically connected to the
digital I/O.
[0033] In FIG. 2A, the termination circuit 22a includes a low
impedance loss path. The low impedance loss path is in parallel
with the effective capacitance of the load on the digital I/O die
pad 18a. As illustrated, the load includes the ESD protection
circuit 24a and the I/O buffer 26a. The effective capacitance of
the load can be modeled by a capacitor having a first end
electrically connected to the digital I/O line 20a and a second end
electrically connected to ground. The illustrated low impedance
loss path is a series RC circuit that includes a capacitor C and a
resistor R. The amounts of capacitance and resistance of the
capacitor C and the resistor R can be selected such that the
termination circuit terminates at a frequency of the RF signal
carried by the RF bond wire 16b. The capacitance of the capacitor C
can be selected such that it is greater than the effective
capacitance of the ESD protection circuit 24a and the I/O buffer
26a. For instance, in certain implementations, the capacitance of
the capacitor C can at least about 5 times the effective
capacitance of the ESD protection circuit 24a and the I/O buffer
26a. As one example, the resistor R can have an impedance that is
between the impedance of the capacitor C and the effective
capacitance of the load at a frequency of an RF signal carried by
the RF bond wire 16b.
[0034] As an example, if an effective capacitance of a digital load
is about 200 fF, which can have an impedance of about -j160 Ohms at
an operating frequency of 5 GHz, the capacitance of the capacitor C
can be selected to be about 1 pF, which corresponds to an impedance
of about -j30 ohms at 5 GHz, wherein j corresponds to the square
root of negative 1. More generally, the capacitance of the
capacitor C can be selected to be relatively large such that the
termination impedance dominates an impedance of the digital load at
a selected frequency and provides a "real" impedance or resistive
load for dampening oscillations. For instance, the capacitance of
the capacitor C can be selected such that the impedance at the RF
frequency of the capacitor C is approximately five times lower than
the impedance of the load at the selected frequency. The resistance
of the resistor R can be selected such that the associated resonant
circuit has a quality factor of less than 1. In the example above
with the capacitor C having a capacitance of about 1 pF, the
resistor R can have an impedance of about 50 Ohms. This can provide
a Q of 0.6 at 5 GHz (j30/50=0.6). In this example, the magnitude of
the impedance of the low impedance loss path should be less than
magnitude of the digital load at the selected frequency (e.g., 5
GHz).
[0035] In FIG. 2A, a first end of the series RC circuit is
electrically connected to the digital I/O die pad 18a and a second
end of the series RC circuit is electrically connected to a ground
potential. Accordingly, the series RC circuit is a series RC shunt
circuit. The low impedance loss path can dampen the resonance of
the load on the die that is connected to the digital I/O die pad
18a. At the same time, the low impedance loss path can prevent the
crosstalk from the RF I/O bond wire 16b without significantly
impacting the performance of the ESD protection circuit 24a. As
such, the performance of the ESD protection circuit 24a can be
maintained over a relatively wide bandwidth.
[0036] FIG. 2A illustrates an example termination circuit 22a.
Other termination circuits can alternatively or additionally be
implemented to prevent ripples on an I/O. FIGS. 2B and 2C provide
two examples of such other termination circuits. Termination
circuits configured to prevent ripples on I/Os can include, for
example, an RC circuit, an RLC circuit, or multiple RC circuits
and/or RLC circuits in parallel and/or in series. Such termination
circuits can be electrically connected between an I/O path and
ground or another reference voltage. Such termination circuits can
be in parallel with an effective capacitance of an ESD protection
circuit that is also electrically connected to the I/O line. Any of
the termination circuits discussed herein can be electrically
connected to any of the non-RF I/O paths discussed herein.
[0037] Referring to FIG. 2B, a schematic diagram that includes an
I/O that experiences radio frequency current due to crosstalk and
another embodiment of a termination circuit electrically connected
to the I/O will be described. The circuits in FIG. 2B can be
substantially the same as and/or functionally similar to the
circuits of FIG. 2A, except that in FIG. 2B a termination circuit
22a' is implemented in place of the termination circuit 22a of FIG.
2A. In FIG. 2B, the termination circuit 22' includes parallel RC
circuits. The termination circuit 22' also includes a first
resistor R1 in series with the parallel RC circuits. The parallel
RC circuits include a first RC circuit and a second RC circuit. The
first RC circuit includes a first capacitor C.sub.1 in series with
a second resistor R.sub.2. The second RC circuit includes a second
capacitor C.sub.2 in series with a third resistor R.sub.3. As
illustrated in FIG. 2B, the termination circuit 22' is electrically
connected between the digital I/O path and ground. The termination
circuit 22' is in parallel with an effective capacitance of an ESD
protection circuit 24a. The resistances and capacitances of the
elements of the termination circuit 22' can be selected to mitigate
the effects of crosstalk with the RF I/O path shown in FIG. 2B.
[0038] Referring to FIG. 2C, a schematic diagram that includes an
I/O that experiences radio frequency current due to crosstalk and
another embodiment of a termination circuit electrically connected
to the I/O will be described. The circuits in FIG. 2C can be
substantially the same as and/or functionally similar to the
circuits of FIGS. 2A and 2B, except that in FIG. 2C a termination
circuit 22a'' is implemented in place of the termination circuit
22a of FIG. 2A or the termination circuit 22' of FIG. 2B. In FIG.
2C, the termination circuit 22'' includes an RC termination circuit
that is electrically connected between the digital I/O path and a
supply voltage .sub.VSUPPLY. The termination circuit 22'' is also
electrically connected in parallel with an effective capacitance of
an ESD protection circuit. In FIG. 2C, the effective capacitance of
the ESD protection circuit is illustrated as a capacitor C.sub.ESD.
FIG. 2C illustrates that any of the termination circuits discussed
herein can be electrically connected between a non-RF I/O path and
a reference voltage. The reference voltage can be, for example, a
supply voltage as illustrated in FIG. 2C. In some other
embodiments, such as the embodiments of FIGS. 2A and 2B, the
reference voltage can be ground. The reference voltage can also be
a different voltage than ground or a supply voltage in certain
implementations.
[0039] Referring to FIG. 3, a schematic diagram of a die 12 that
includes a radio frequency input/output line 21b and another
input/output line that is electrically connected to a termination
circuit 22a will be described. It will be understood that the die
12 can include more elements than illustrated and/or that some
embodiments include a subset of the illustrated elements. The die
12 of FIG. 3 can include any combination of features of the die 12
discussed with reference to FIG. 1.
[0040] In FIG. 3, the die 12 includes a plurality of I/O contacts.
The I/O contacts can include die pads 18a and 18b as illustrated.
In other embodiments, the I/O contacts can be implemented by pins,
solder bumps, beam leads, or the like. A first contact of the die
12, such as the first bond pad 18b, can receive an RF signal and
provide the RF signal to an RF I/O line 21b that carries the RF
signal to an RF load 28. The RF I/O line 21b is included in an RF
I/O path that is configured to process RF signals. A second contact
of the die 12, such as the second bond pad 18a, can receive a
second signal and provide the second signal to a second I/O line.
The second I/O line can be any suitable line electrically connected
to a contact of the die 12 with a capacitive load coupled thereto.
The second signal can be a non-RF signal. Accordingly, the second
I/O line can provide the second signal to circuits that are
configured to process signals at frequencies other than RF
frequencies, such as at baseband or direct current (DC). As shown
in FIG. 3, the second signal can be a digital signal provided to
the digital I/O line 20a. The digital I/O line 20a can be included
in a digital I/O path that is configured to process digital
signals. The second signal can be provided to a load 30 on the die
12. The load 30 can include an ESD protection circuit and/or an I/O
buffer, for example.
[0041] The termination circuit 22a is also included on the die 12
of FIG. 3. In some other embodiments, some or all of the
termination circuit 22a can be implemented external to the die 12.
Such an external termination circuit can include a resistor
external to the die 12 and/or a surface mounted capacitor, for
example. The termination circuit 22a can mitigate effects of
crosstalk from the RF I/O line 21b on the second I/O line. For
instance, the termination circuit 22a can prevent crosstalk from
the RF I/O line 21b from creating a resonance on the second I/O
line, such as a resonance due to the effective capacitance of the
load 30 resonating. The termination circuit 22a can prevent
crosstalk from the RF I/O from significantly impacting performance
of an ESD protection circuit of the load 30 over frequency.
[0042] Various types of coupling can cause crosstalk between the RF
I/O path and the second I/O path. For instance, as discussed above,
such crosstalk can be due to coupling between adjacent bond wires.
In other instances, crosstalk between the RF I/O path and the
second I/O path can be due to coupling between conductive traces on
a printed circuit board, due to on die coupling between these paths
through a substrate, the like, or any combination thereof. The
termination circuit 22a can mitigate the effects of crosstalk from
any of these types of coupling.
[0043] The systems, apparatus, and methods related to ripple
termination on I/Os are described above with reference to certain
embodiments. A skilled artisan will, however, appreciate that the
principles and advantages of the embodiments can be used for any
other systems, apparatus, or methods with a need for a termination
circuit on an I/O.
[0044] Such systems, apparatus, and/or methods can be implemented
in various electronic devices. Examples of the electronic devices
can include, but are not limited to, consumer electronic products,
parts of the consumer electronic products, electronic test
equipment, etc. Examples of the electronic devices can also include
control chips, memory chips, memory modules, circuits of optical
networks or other communication networks, and disk driver circuits.
Some example control chips include a digital attenuator, a voltage
variable attenuator, a switch component including a multi-throw
switch, and a phase shifter. The consumer electronic products can
include, but are not limited to, precision instruments, medical
devices, wireless devices, a mobile phone (for example, a smart
phone), cellular base stations, a telephone, a television, a
computer monitor, a computer, a hand-held computer, a tablet
computer, a personal digital assistant (PDA), a microwave, a
refrigerator, a stereo system, a cassette recorder or player, a DVD
player, a CD player, a digital video recorder (DVR), a VCR, an MP3
player, a radio, a camcorder, a camera, a digital camera, a
portable memory chip, a washer, a dryer, a washer/dryer, a copier,
a facsimile machine, a scanner, a multi-functional peripheral
device, a wrist watch, a clock, etc. Further, the electronic device
can include unfinished products.
[0045] Unless the context clearly requires otherwise, throughout
the description and the claims, the words "comprise," "comprising,"
"include," "including," and the like are to be construed in an
inclusive sense, as opposed to an exclusive or exhaustive sense;
that is to say, in the sense of "including, but not limited to."
The words "coupled" or "connected", as generally used herein, refer
to two or more elements that may be either directly connected, or
connected by way of one or more intermediate elements.
Additionally, the words "herein," "above," "below," and words of
similar import, when used in this application, shall refer to this
application as a whole and not to any particular portions of this
application. Where the context permits, words in the Detailed
Description of Certain Embodiments using the singular or plural
number may also include the plural or singular number,
respectively. The words "or" in reference to a list of two or more
items, is intended to cover all of the following interpretations of
the word: any of the items in the list, all of the items in the
list, and any combination of the items in the list. All numerical
values or distances provided herein are intended to include similar
values within a measurement error.
[0046] The teachings of the inventions provided herein can be
applied to other systems, not necessarily the systems described
above. The elements and acts of the various embodiments described
above can be combined to provide further embodiments. The acts of
the methods discussed herein can be performed in any order as
appropriate. Moreover, the acts of the methods discussed herein can
be performed serially or in parallel, as appropriate.
[0047] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the disclosure. Indeed, the novel
apparatus, systems, and methods described herein may be embodied in
a variety of other forms. For instance, it will be understood that
the principles and advantages discussed herein can be used in any
suitable integrated circuit with a need for a termination circuit
on an I/O. Furthermore, various omissions, substitutions and
changes in the form of the methods and systems described herein may
be made without departing from the spirit of the disclosure. The
accompanying claims and their equivalents are intended to cover
such forms or modifications as would fall within the scope and
spirit of the disclosure. Accordingly, the scope of the present
inventions is defined by reference to the claims.
* * * * *