U.S. patent application number 13/183413 was filed with the patent office on 2013-01-17 for wireless circuitry for simultaneously receiving radio-frequency transmissions in different frequency bands.
The applicant listed for this patent is Ronald W. Dimpflmaier, Nicholas W. Lum, Louie J. Sanguinetti. Invention is credited to Ronald W. Dimpflmaier, Nicholas W. Lum, Louie J. Sanguinetti.
Application Number | 20130016633 13/183413 |
Document ID | / |
Family ID | 46514786 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130016633 |
Kind Code |
A1 |
Lum; Nicholas W. ; et
al. |
January 17, 2013 |
Wireless Circuitry for Simultaneously Receiving Radio-frequency
Transmissions in Different Frequency Bands
Abstract
An electronic device has wireless communications circuitry that
includes transmitters and receivers. Antenna structures may be
coupled to the transmitters and receivers to support
radio-frequency signal transmission and radio-frequency signal
reception operations. Switching circuitry such may be used to
support multiple communications bands of interest. One or more low
band receivers may be associated with the first switch and one or
more high band receivers may be associated with the second switch.
The switches can be configured in real time to switch a desired
communications band into use. A diplexer may be used to
simultaneously pass low bands to the first receiver and high bands
to the second receiver. In this way, a data stream in the low band
may be simultaneously received with a data stream in the high
band.
Inventors: |
Lum; Nicholas W.; (Santa
Clara, CA) ; Dimpflmaier; Ronald W.; (Los Gatos,
CA) ; Sanguinetti; Louie J.; (Los Gatos, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lum; Nicholas W.
Dimpflmaier; Ronald W.
Sanguinetti; Louie J. |
Santa Clara
Los Gatos
Los Gatos |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
46514786 |
Appl. No.: |
13/183413 |
Filed: |
July 14, 2011 |
Current U.S.
Class: |
370/277 ;
370/297 |
Current CPC
Class: |
H04L 5/001 20130101;
H04B 1/0057 20130101; H04B 1/16 20130101 |
Class at
Publication: |
370/277 ;
370/297 |
International
Class: |
H04L 5/14 20060101
H04L005/14; H04B 7/00 20060101 H04B007/00 |
Claims
1. A method of receiving radio-frequency transmissions with an
electronic device, comprising: with an antenna in the electronic
device, receiving at least first and second data streams in at
least first and second respective communications bands; with a
diplexer, routing the first data stream to a first receiver and
routing the second data stream to a second receiver; simultaneously
receiving the first data stream using the first receiver and the
second data stream using the second receiver; and with baseband
processor circuitry in the electronic device, combining the first
data stream received by the first receiver with the second data
stream received by the second receiver.
2. The method defined in claim 1 wherein the diplexer comprises a
low pass filter, wherein routing the first data stream to the first
receiver comprises: with the low pass filter, routing the first
data stream to the first receiver and blocking the second data
stream from reaching the first receiver.
3. The method defined in claim 1 wherein the diplexer comprises a
high pass filter, wherein routing the second data stream to the
second receiver comprises: with the high pass filter, routing the
second data stream to the second receiver and blocking the first
data stream from reaching the second receiver.
4. The method defined in claim 1 further comprising: with a
switching circuit that is interposed between the first receiver and
the diplexer, receiving the first data stream; and with the
switching circuit, routing the first data stream to a duplexer that
is associated with the first communications band.
5. The method defined in claim 4 further comprising: with the
duplexer, routing the first data stream to an additional switching
circuit that is interposed between the duplexer and the first
receiver.
6. The method defined in claim 5 further comprising: configuring
the additional switching circuit to route the first data stream to
the first receiver.
7. The method defined in claim 1 further comprising: with the first
receiver, demodulating the first data stream; and with the second
receiver, demodulating the second data stream.
8. Wireless communications circuitry, comprising: a first
radio-frequency receiver configured to operate in a first
communications band; a second radio-frequency receiver configured
to operate in a second communications band; an antenna configured
to receive at least a first data stream in a first communications
band and a second data stream in a second communications band; a
diplexer having a first port that is coupled to the first
radio-frequency receiver, a second port that is coupled to the
second radio-frequency receiver, and a third port that is coupled
to the antenna; and baseband circuitry configured to simultaneously
receive the first data stream from the first radio-frequency
receiver and the second data stream from the second radio-frequency
receiver.
9. The wireless circuitry defined in claim 8 wherein the first
radio-frequency receiver comprises a Long Term Evolution (LTE)
cellular telephone receiver configured to operate in LTE Band 17
and wherein the second radio-frequency receiver includes an LTE
cellular telephone receiver configured to operate in LTE band
4.
10. The wireless circuitry defined in claim 8 wherein the diplexer
comprises a low pass filter and a high pass filter.
11. The wireless circuitry defined in claim 10 wherein the low pass
filter is configured to pass frequencies associated with the first
data stream without passing frequencies associated with the second
data stream.
12. The wireless circuitry defined in claim 11 wherein the high
pass filter is configured to pass frequencies associated with the
second data stream without passing frequencies associated with the
first data stream.
13. The wireless circuitry defined in claim 10 further comprising:
a first duplexer that is interposed between the diplexer and the
first radio-frequency receiver and is configured to route the first
data stream to the first radio-frequency receiver; and a second
duplexer that is interposed between the diplexer and the second
radio-frequency receiver and is configured to route the second data
stream to the second radio-frequency receiver.
14. The wireless circuitry defined in claim 13 further comprising:
oscillator circuitry coupled to the first receiver and the second
receiver that is configured to provide the first receiver with a
first signal at a first frequency associated with the first data
stream and configured to provide the second receiver with a second
signal at a second frequency associated with the second data
stream.
15. A method of operating wireless communications circuitry,
comprising: receiving instructions from a base station that direct
the wireless communications circuitry to prepare for simultaneous
receipt of a first data stream in a first communications band and a
second data stream in a second communications band; in response to
receiving the instructions from the base station, configuring
switching circuitry in the wireless circuitry to form a first
signal path and a second signal path; with an antenna in the
wireless circuitry, receiving the first and second data streams;
with a diplexer in the wireless circuitry, routing the first data
stream through the first signal path and routing the second data
stream through the second signal path; and simultaneously receiving
the first data stream at a first receiver coupled to the first
signal path and the second data stream at a second receiver coupled
to the second signal path.
16. The method defined in claim 15 wherein receiving instructions
from the base station comprises receiving instructions from the
base station to operate in a carrier aggregation mode.
17. The method defined in claim 15 wherein the diplexer comprises a
low pass filter and wherein routing the first data stream through
the first signal path comprises isolating the first data stream
from the second data stream with the low pass filter.
18. The method defined in claim 17 wherein the diplexer further
comprises a high pass filter and wherein routing the second data
stream through the second signal path comprises isolating the
second data stream from the first data stream with the high pass
filter.
19. The method defined in claim 15 further comprising: with a first
oscillating circuit, providing a first local oscillator signal at a
first frequency associated with the first communications band to
the first radio-frequency receiver; and with a second oscillating
circuit, providing a second local oscillator signal at a second
frequency associated with the second communications band to the
second radio-frequency receiver.
20. The method defined in claim 15 further comprising: with
baseband circuitry, receiving the first and second data streams
from the first and second radio-frequency receivers; and combining
the first and second data streams to form a single data stream.
Description
BACKGROUND
[0001] This relates generally to wireless communications circuitry,
and more particularly, to circuitry in wireless electronic devices
that reduces interference from frequency harmonics and
simultaneously receives radio-frequency transmissions in different
frequency bands.
[0002] Electronic devices such as computers and cellular telephones
are often provided with wireless communications capabilities. For
example, electronic devices may use long-range wireless
communications circuitry such as cellular telephone circuitry.
Global Positioning System (GPS) receiver circuitry and other
satellite receiver circuitry may be used to receive satellite
navigation signals. Local wireless links may be used to support
local area network communications such as IEEE 802.11
communications at 2.4 GHz and 5 GHz. Local links may also be used
to handle Bluetooth.RTM. communications at 2.4 GHz.
[0003] It is often desirable for a device to support multiple
bands. For example, users of a cellular telephone may desire to
communicate with cellular telephone towers using one or more
different cellular telephone bands and may desire to communicate
with local area network equipment using wireless local area network
(WLAN) communications bands.
[0004] When supporting multiple bands, it is sometimes desirable to
use configurable switching circuitry to route signals. In a device
having a transceiver with numerous transceiver ports, for example,
a switch may be used to selectively couple a selected one of the
transceiver ports to an antenna. This type of configuration allows
the device to be configured in different ways, depending on the
desired band of operation. If, for example, it is desired to use a
first communications band, the switch may be placed in a first
state that couples a first transceiver port to the antenna. When it
is desired to use a second communications band, the switch may be
placed in a second state that couples a second transceiver port to
the antenna.
[0005] Radio-frequency switches may be based on components such as
transistors that exhibit non-linear behavior. As a result,
undesired frequency harmonics may be generated when radio-frequency
signals are transmitted through a switch. For example, second
harmonics, third harmonics, and higher-order harmonics of
transmitted radio-frequency signals may be generated. If care is
not taken, these harmonic signals may interfere with the operation
of receiver circuitry in the device. For example, harmonics that
are generated during transmission of cellular telephone signals may
interfere with proper operation of a satellite navigation receiver
or wireless local area network receiver.
[0006] Wireless devices may be required to simultaneously receive
radio-frequency transmissions in two or more frequency bands. For
example, a wireless cellular device that communicates with a base
station using a Long Term Evolution (LTE) protocol may be required
to receive radio-frequency transmissions from the base station in
two separate LTE bands.
[0007] To handle wireless communications in environments such as
these, it would be desirable to be able provide improved circuitry
for routing signals between radio-frequency transceiver ports and
antenna structures in a wireless electronic device.
SUMMARY
[0008] An electronic device may be provided with wireless
communications circuitry. The wireless communications circuitry may
include radio-frequency transceiver circuitry for handling wireless
communications. The radio-frequency transceiver may have multiple
transmitters and multiple receivers. Antenna structures may be used
to transmit and receive signals.
[0009] The antenna structures may be coupled to transmitters and
receivers in the radio-frequency transceiver circuitry. Switching
circuitry such as first and second radio-frequency switches may be
used to support multiple communications bands of interest. The
first and second radio-frequency switches may be configured in real
time to switch desired frequencies into use.
[0010] A set of low band transmitters and receivers may be
associated with the first switch and a set of high band
transmitters and receivers may be associated with the second
switch. As transmitted signals at frequency f pass through the
switches, harmonics at 2f, 3f, and other integral multiples of the
transmitted signals may be produced.
[0011] A diplexer may be interposed between the first and second
switches and the antenna structures. The diplexer may have a first
port that is coupled to the first radio-frequency switch, a second
port that is coupled to the second radio-frequency switch, and a
third port that is coupled to one or more antennas in the antenna
structures.
[0012] The diplexer may include a low band filter associated with
the low band transmitters and receivers and a high band filter
associated with the high band transmitters and receivers. The low
band filter may be a low pass filter that is coupled between the
first switch and the antenna structures. The low pass filter may
prevent transmitted signal harmonics that exit the first switch
from reaching the antenna structures. The diplexer may include high
band and low band filters that exhibit high degrees of linearity
such as filters implemented on ceramic substrates. Highly linear
filters such as filters with ceramic substrates may have a reduced
tendency to produce undesired harmonics relative to other filter
designs.
[0013] The high band filter may be a high pass filter or a band
pass filter. When implemented using a bandpass filter, the high
band filter may prevent transmitted signal harmonics that exit the
second switch from reaching the antenna structures.
[0014] The diplexer may be configured to pass low bands to a first
receiver and high bands to a second receiver. In this way, a first
frequency band may be received and processed by the first receiver
and a second frequency band may be received and processed by the
second frequency band.
[0015] Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic diagram of an illustrative electronic
device with wireless communications circuitry in accordance with an
embodiment of the present invention.
[0017] FIG. 2 is a diagram showing how radio-frequency transceiver
circuitry may be coupled to one or more antennas within an
electronic device of the type shown in FIG. 1 in accordance with an
embodiment of the present invention.
[0018] FIG. 3 is a circuit diagram of illustrative wireless
communications circuitry of the type that may be used in handling
wireless communications in the electronic device of FIG. 1 in
accordance with an embodiment of the present invention.
[0019] FIG. 4 is a graph of radio-frequency signal transmission as
a function of operating frequency for an illustrative low band
filter that may be used in a diplexer within the wireless circuitry
of FIG. 3 in accordance with an embodiment of the present
invention.
[0020] FIG. 5 is a graph of radio-frequency signal transmission as
a function of operating frequency for an illustrative high band
filter that may be used in a diplexer within the wireless circuitry
of FIG. 3 in accordance with an embodiment of the present
invention.
[0021] FIG. 6 is a circuit diagram of illustrative wireless
communications circuitry that may be configured to simultaneously
receive radio-frequency transmissions in different frequency bands
in accordance with an embodiment of the present invention.
[0022] FIG. 7 is a graph of illustrative frequency bands that may
be simultaneously received with wireless communications circuitry
such as the wireless communications circuitry of FIG. 6 in
accordance with an embodiment of the present invention.
[0023] FIG. 8 is a flow chart of illustrative steps that may be
performed with a wireless electronic device to simultaneously
receive radio-frequency transmissions in different frequency bands
in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[0024] Electronic devices such as device 10 of FIG. 1 may be
provided with wireless communications circuitry. The wireless
communications circuitry may be used to support long-range wireless
communications such as communications in cellular telephone bands.
Examples of long-range (cellular telephone) bands that may be
handled by device 10 include the 800 MHz band, the 850 MHz band,
the 900 MHz band, the 1800 MHz band, the 1900 MHz band, the 2100
MHz band, the 700 MHz band, and other bands. The long-range bands
used by device 10 may include the so-called LTE (Long Term
Evolution) bands. The LTE bands are numbered (e.g., 1, 2, 3, etc.)
and are sometimes referred to as E-UTRA operating bands. Long-range
signals such as signals associated with satellite navigation bands
may be received by the wireless communications circuitry of device
10. For example, device 10 may use wireless circuitry to receive
signals in the 1575 MHz band associated with Global Positioning
System (GPS) communications. Short-range wireless communications
may also be supported by the wireless circuitry of device 10. For
example, device 10 may include wireless circuitry for handling
local area network links such as WiFi.RTM. links at 2.4 GHz and 5
GHz, Bluetooth.RTM. links at 2.4 GHz, etc.
[0025] As shown in FIG. 1, device 10 may include storage and
processing circuitry 28. Storage and processing circuitry 28 may
include storage such as hard disk drive storage, nonvolatile memory
(e.g., flash memory or other electrically-programmable-read-only
memory configured to form a solid state drive), volatile memory
(e.g., static or dynamic random-access-memory), etc. Processing
circuitry in storage and processing circuitry 28 may be used to
control the operation of device 10. This processing circuitry may
be based on one or more microprocessors, microcontrollers, digital
signal processors, application specific integrated circuits,
etc.
[0026] Storage and processing circuitry 28 may be used to run
software on device 10, such as internet browsing applications,
voice-over-internet-protocol (VOIP) telephone call applications,
email applications, media playback applications, operating system
functions, functions related to communications band selection
during radio-frequency transmission and reception operations, etc.
To support interactions with external equipment, storage and
processing circuitry 28 may be used in implementing communications
protocols. Communications protocols that may be implemented using
storage and processing circuitry 28 include internet protocols,
wireless local area network protocols (e.g., IEEE 802.11
protocols--sometimes referred to as WiFi.RTM.), protocols for other
short-range wireless communications links such as the
Bluetooth.RTM. protocol, cellular telephone protocols, MIMO
(multiple input multiple output) protocols, antenna diversity
protocols, etc. Wireless communications operations such as
communications band selection operations may be controlled using
software stored and running on device 10 (i.e., stored and running
on storage and processing circuitry 28 and/or input-output
circuitry 30).
[0027] Input-output circuitry 30 may include input-output devices
32. Input-output devices 32 may be used to allow data to be
supplied to device 10 and to allow data to be provided from device
10 to external devices. Input-output devices 32 may include user
interface devices, data port devices, and other input-output
components. For example, input-output devices may include touch
screens, displays without touch sensor capabilities, buttons,
joysticks, click wheels, scrolling wheels, touch pads, key pads,
keyboards, microphones, cameras, buttons, speakers, status
indicators, light sources, audio jacks and other audio port
components, digital data port devices, light sensors, motion
sensors (accelerometers), capacitance sensors, proximity sensors,
etc.
[0028] Input-output circuitry 30 may include wireless
communications circuitry 34 for communicating wirelessly with
external equipment. Wireless communications circuitry 34 may
include radio-frequency (RF) transceiver circuitry formed from one
or more integrated circuits, power amplifier circuitry, low-noise
input amplifiers, passive RF components, one or more antennas,
transmission lines, and other circuitry for handling RF wireless
signals. Wireless signals can also be sent using light (e.g., using
infrared communications).
[0029] Wireless communications circuitry 34 may include
radio-frequency transceiver circuitry 90 for handling various
radio-frequency communications bands. For example, circuitry 34 may
include transceiver circuitry 36, 38, and 42. Transceiver circuitry
36 may handle 2.4 GHz and 5 GHz bands for WiFi.RTM. (IEEE 802.11)
communications and may handle the 2.4 GHz Bluetooth.RTM.
communications band. Circuitry 34 may use cellular telephone
transceiver circuitry 38 for handling wireless communications in
cellular telephone bands such as at 850 MHz, 900 MHz, 1800 MHz,
1900 MHz, and 2100 MHz and/or the LTE bands and other bands (as
examples). Circuitry 38 may handle voice data and non-voice
data.
[0030] Wireless communications circuitry 34 may include global
positioning system (GPS) receiver equipment such as GPS receiver
circuitry 42 for receiving GPS signals at 1575 MHz or for handling
other satellite positioning data. In WiFi.RTM. and Bluetooth.RTM.
links and other short-range wireless links, wireless signals are
typically used to convey data over tens or hundreds of feet. In
cellular telephone links and other long-range links, wireless
signals are typically used to convey data over thousands of feet or
miles.
[0031] Wireless communications circuitry 34 may include one or more
antennas 40. Antennas 40 may be formed using any suitable antenna
types. For example, antennas 40 may include antennas with
resonating elements that are formed from loop antenna structure,
patch antenna structures, inverted-F antenna structures, slot
antenna structures, planar inverted-F antenna structures, helical
antenna structures, hybrids of these designs, etc. Different types
of antennas may be used for different bands and combinations of
bands. For example, one type of antenna may be used in forming a
local wireless link antenna and another type of antenna may be used
in forming a remote wireless link antenna.
[0032] Antenna diversity schemes may be implemented in which
multiple redundant antennas are used in handling communications for
a particular band or bands. In an antenna diversity scheme, storage
and processing circuitry 28 may select which antenna to use in real
time based on signal strength measurements or other data. In
multiple-input-multiple-output (MIMO) schemes, multiple antennas
may be used to transmit and receive multiple data streams, thereby
enhancing data throughput.
[0033] Illustrative locations in which antennas 40 may be formed in
device 10 are shown in FIG. 2. As shown in FIG. 2, electronic
device 10 may have a housing such as housing 12. Housing 12 may
include plastic walls, metal housing structures, structures formed
from carbon-fiber materials or other composites, glass, ceramics,
or other suitable materials. Housing 12 may be formed using a
single piece of material (e.g., using a unibody configuration) or
may be formed from a frame, housing walls, and other individual
parts that are assembled to form a completed housing structure. The
components of device 10 that are shown in FIG. 1 may be mounted
within housing 12. Antenna structures 40 may be mounted within
housing 12 and may, if desired, be formed using parts of housing
12. For example, housing 12 may include metal housing sidewalls,
peripheral conductive members such as band-shaped members (with or
without dielectric gaps), conductive bezels, and other conductive
structures that may be used in forming antenna structures 40.
[0034] As shown in FIG. 2, antenna structures 40 may be coupled to
transceiver circuitry 90 by paths such as paths 45. Paths 45 may
include transmission line structures such as coaxial cables,
microstrip transmission lines, stripline transmission lines, etc.
Paths 45 may also include impedance matching circuitry, filter
circuitry, and switching circuitry. Impedance matching circuitry
may be used to ensure that antennas 40 are efficiently coupled to
transceiver circuitry 90 in communications bands of interest.
Filter circuitry may be used to implement frequency-based
multiplexing circuits such as diplexers, duplexers, and triplexers.
Switching circuitry may be used to selectively couple antennas 40
to desired ports of transceiver circuitry 90. For example, in one
operating mode a switch may be configured to route one of paths 45
to a given antenna and in another operating mode the switch may be
configured to route a different one of paths 45 to the given
antenna. The use of switching circuitry between transceiver
circuitry 90 and antennas 40 allows device 10 to support multiple
communications bands of interest with a limited number of
antennas.
[0035] In a device such as a cellular telephone that has an
elongated rectangular outline, it may be desirable to place
antennas 40 at one or both ends of the device. As shown in FIG. 2,
for example, some of antennas 40 may be placed in upper end region
42 of housing 12 and some of antennas 40 may be placed in lower end
region 44 of housing 12. The antenna structures in device 10 may
include a single antenna in region 42, a single antenna in region
44, multiple antennas in region 42, multiple antennas in region 44,
or may include one or more antennas located elsewhere in housing
12.
[0036] Antenna structures 40 may be formed within some or all of
regions such as regions 42 and 44. For example, an antenna such as
antenna 40T-1 may be located within region 42-1 or an antenna such
as antenna 40T-2 may be formed that fills some or all of region
42-1. An antenna such as antenna 40B-1 may fill some or all of
region 44-2 or an antenna such as antenna 40B-2 may be formed in
region 44-1. These types of arrangements need not be mutually
exclusive. For example, region 44 may contain a first antenna such
as antenna 40B-1 and a second antenna such as antenna 40B-2.
[0037] Transceiver circuitry 90 may contain transmitters such as
transmitters 48 and receivers such as receivers 50. Transmitters 48
and receivers 50 may be implemented using one or more integrated
circuits (e.g., cellular telephone communications circuits,
wireless local area network communications circuits, circuits for
Bluetooth.RTM. communications, circuits for receiving satellite
navigation system signals, power amplifier circuits for increasing
transmitted signal power, low noise amplifier circuits for
increasing signal power in received signals, other suitable
wireless communications circuits, and combinations of these
circuits).
[0038] Device 10 may be a relatively large device (e.g. the lateral
dimensions of housing 12 may be tens of centimeters or larger) or
may be a relatively compact device such as a handheld device that
has a longitudinal dimension along the main axis of housing 12 that
is 15 cm or less, 10 cm or less, or 5 cm or less, and that has
smaller transverse dimensions. In miniature devices such as
wrist-mounted, pendant, and clip-mounted devices, the dimensions of
housing 12 may be 10 cm or less or 5 cm or less (as examples).
[0039] Particularly in housings for device 10 that are compact, it
may be difficult or impossible to widely separate various antennas
from each other. For example, some antennas (e.g., antennas 40T-1
and 40T-2 in the example of FIG. 2) may be located adjacent to each
other within housing 12. Other antennas (e.g., the antenna
structures of region 42 and the antenna structures of region 44)
may be separated only by the relatively modest length of device
10.
[0040] Due to the close proximity of the antennas within device 10
in at least some device configurations, there may be a potential
for interference between bands. This potential for interference may
be exacerbated by the presence of the circuitry in paths 45, which
may generate undesirable frequency harmonics. For example, switches
in paths 45 may have non-linear properties that lead to the
generation of second harmonics, third harmonics, and higher-order
harmonics when passing radio-frequency signals.
[0041] During data transmission operations, radio-frequency signals
that are generated by transceiver 90 may are transmitted through
paths 45 to antennas 40. Transmitted signals may, for example, be
generated at a frequency f at one of the ports associated with
transceiver 90. Frequency f may be associated with a cellular
telephone band or other frequency of interest. Paths 45 may contain
a switch such as a transistor-based switch. As the signals at
frequency f pass through the switch (and other non-linear circuit
elements in paths 45), frequency harmonics may be generated at
frequencies such as 2f, 3f, 4f, and higher. In this situation, a
signal harmonic at 2f, 3f, 4f, or higher might be transmitted from
one antenna (e.g., a cellular telephone antenna) at the same time
that signals at frequency f are being transmitted. The frequency
harmonics at 2f, 3f, and 4f might then be received by another
antenna in the device (e.g., a wireless local area network antenna
or satellite navigation antenna). If care is not taken, the
received signals at harmonic frequencies of frequency f may cause
undesirable interference. For example, a received signal at 2f, 3f,
or 4f might fall within or near a communications band of one of
receivers 50 (e.g., a wireless local area network receiver or
satellite navigation system receiver). Left uncorrected, the
presence of this type of interference may prevent satisfactory
simultaneous operation of the transmitter at frequency f and the
receiver operating at 2f, 3f, 4f, or other harmonic.
[0042] Device 10 can reduce or eliminate this type of undesirable
interference by including filtering circuitry in paths 45 that
blocks harmonics associated with transmitted signals before they
reach antennas 40. Because the magnitude of transmitted harmonics
is substantially reduced, the magnitude of any harmonics that are
received by other antenna and receiver circuitry in device 10 is
substantially reduced. By effectively preventing harmonics from
being transmitted, the potential for signal interference is
eliminated and satisfactory device operation is ensured.
[0043] The filtering circuitry may include a diplexer filter that
is used to multiplex low band and high band transmitted signals
onto a common transmit path. During signal reception operations,
the diplexer demultiplexes received signals based on their
frequency. The diplexer may include a low pass filter that is
coupled to low band transceiver ports through a low band switch.
The diplexer may also include a high pass filter or a bandpass
filter that is coupled to high band transceiver ports through a
high band switch.
[0044] Even if harmonics are generated in the switches, the
harmonics will be blocked by the filtering circuitry of the
diplexer. For example, consider a low band frequency such as
frequency f. As a signal at this frequency passes through the low
band switch, harmonic signals at 2f, 3f, and 4f may be generated.
By proper configuration of the cutoff frequency of the low pass
filter, signal frequency f will fall within the pass band of the
low pass filter, but signal frequencies 2f, 3f, and 4f will fall
outside of the pass band and will be attenuated. Because the low
pass filter blocks undesired harmonic frequencies, receivers 50 in
device 10 that operate at or near harmonic frequencies (e.g., 2f,
3f, 4f, and higher) will not be subject to harmonic interference
and can operate at the same time as the transmitter operating at
frequency f. Frequency harmonics generated when transmitting
signals from the high band transceiver through the high band switch
can likewise be attenuated by the high-frequency attenuation
properties of the high-band filter (i.e., when the high-band filter
is implemented using a bandpass filter that passes desired
high-band frequencies while attenuating harmonics of these desired
high-band frequencies).
[0045] A filtering arrangement based on a diplexer scheme of this
type may exhibit lower insertion loss than filtering arrangements
based on components with higher insertion losses such as notch
filters. If desired, additional filtering circuitry may be used in
device 10. In general, the filtering circuitry in paths 45 may,
include diplexers, duplexers, triplexers, notch filters, bandpass
filters, low pass filters, high pass filters, other filter
components, and combinations of filter circuits such as these.
Filtering components may, for example, be implemented using surface
acoustic wave (SAW) or bulk acoustic wave (BAW) devices.
[0046] An illustrative configuration that may be used for wireless
communications circuitry 34 is shown in FIG. 3. As shown in FIG. 3,
device 10 may include antennas 40 in housing 12. Antennas 40 may be
coupled to transceiver circuitry 38 and 46 using paths 45. Paths 45
may include switching circuitry 64.
[0047] Antennas 40 may include one or more antennas. One or more
antennas 40 may, for example, be used for cellular telephone
communications bands, one or more antennas 40 may be used for
satellite navigation system bands such as the GPS band at 1575 MHz,
and one or more antennas 40 may be used for other communications
bands of interest (e.g. the IEEE 802.11 bands at 2.4 GHz and 5 GHz
or other wireless local area network bands, the Bluetooth.RTM. band
at 2.4 GHz, etc.). In a configuration of the type shown in the
example of FIG. 3, one or more antennas such as antenna 40A may be
associated with wireless transceiver circuitry such as remote
wireless transceiver circuitry 38 (e.g., one or more cellular
telephone transceiver circuits) and one or more antennas such as
antenna 40B may be associated with wireless transceiver circuitry
46 (e.g., satellite navigation system receiver 42 of FIG. 1, local
wireless transceiver circuits 36 of FIG. 1 such as IEEE 802.11
wireless local area network circuits, Bluetooth.RTM. circuits,
etc.). Additional antennas may be associated with transceiver
circuitry 38 (i.e., antennas in addition to antenna 40A) and
additional antennas may be associated with transceiver circuitry 46
(i.e., antennas in addition to antenna 40B), if desired.
[0048] Transceiver circuitry 38 may include transmitters 48 and
receivers 50. There may be, for example, a respective transmitter
48 and a respective receiver 50 associated with each of a plurality
of cellular telephone communications bands. Consider, as an
example, LTE Band 13. To support communications in E-UTRA (LTE)
Band 13, one of transmitters 48 (e.g., transmitter TX of FIG. 3)
may transmit radio-frequency signals in the uplink frequency range
of 777 MHz to 787 MHz and one of receivers 50 (e.g., receiver RX of
FIG. 3) may receive radio-frequency signals in the downlink
frequency range of 746 MHz to 756 MHz. To increase transmit power
before transmitted radio-frequency signals reach antennas 40, paths
45 may include power amplifiers such as power amplifier 52. To
increase the strength of signals that have been received from
antennas 40, paths 45 may include low noise amplifiers (LNAs) such
as low noise amplifier 60. Amplifiers such as amplifiers 52 and 60
may be implemented using discrete components, using circuitry that
is part of a transceiver integrated circuit, etc.
[0049] Switching circuitry 64 may include multiple switches each of
which is associated with a respective frequency range. In the
example of FIG. 3, switching circuitry 64 includes first switch
64LB and second switch 64HB. The states of switches 64LB and 64HB
(i.e., which terminals are connected to each other in the switches)
may be controlled by using storage and processing circuitry 28 to
apply control signals to control terminals 62. Switch 64LB may be
used to handle radio-frequency signals with lower frequencies than
switch 64HB. With this type of arrangement, switch 64LB may
sometimes be referred to as a low band switch and switch 64HB may
sometimes be referred to as a high band switch.
[0050] Switches 64LB and 64HB preferably have a sufficient number
of terminals (switch ports) to allow all desired transmitters 48
and receivers 50 to be coupled to antennas 40. In a typical
configuration, switches 64LB and 64HB may be SP4T (single pole four
throw) or SP5T (single pole five throw) switches (as an example).
Switches with more terminals or fewer terminals may be used if
desired.
[0051] Each switch has one terminal T' that is coupled to diplexer
68 and a plurality of other terminals T that are each coupled to a
respective portion of transceiver circuitry 38. In a typical
configuration, each transmitter and receiver pair in transceiver
circuitry 38 is coupled to a respective terminal T in switch 64LB
or 64HB using a component such as duplexer 54. With this type of
arrangement, transmit and receive signals for each band of interest
are associated with a respective switch terminal T.
[0052] Each duplexer 54 may be a three port device that has a first
port coupled to a transceiver, a second port coupled to a receiver,
and a third port coupled to one of terminals T. Duplexer 54 may be
formed from filter circuitry that provides high isolation between
the first port and the second port. For example, a duplexer 54 may
be configured to accommodate radio-frequency transmissions
associated with LTE band 5. In this scenario, the first port of
duplexer 54 may be coupled to a transceiver that transmits
radio-frequency signals on the LTE band 5 transmit frequencies
(e.g., 824 MHz to 849 MHz) and the second port of duplexer 54 may
be coupled to a receiver that receives radio-frequency signals on
the LTE band 5 receive frequencies (e.g., 869 MHz to 894 MHz). The
radio-frequency signals transmitted by the transceiver may be much
larger than the radio-frequency signals received by the receiver
(e.g., tens of dBm larger). Duplexer 54 may help prevent the
relatively large signals transmitted by the transceiver from being
received by the receiver, thereby providing high isolation between
the transceiver and the receiver. In other words, duplexer 54 may
provide high out-of-band attenuation for the first and second ports
of duplexer 54.
[0053] In the example of FIG. 3, low band switch 64LB has a
plurality of terminals T each of which is coupled to a respective
transmitter 48 and receiver 50 by a respective path 66 and
associated filter circuitry such as duplexer 54. For example,
transmitter TX may be connected to filter 56 in duplexer 54 and
receiver RX may be connected to filter 58 in duplexer 54. Filter 56
may be a band pass filter that passes signals in the uplink range
of Band 13 and filter 58 may be a band pass filter that passes
signals in the downlink range of Band 13.
[0054] Duplexer 54 may be coupled to a given one of terminals T in
low band switch 64LB by one of paths 66. Transmitted signals from
transmitter TX in the uplink frequency range for Band 13 may be
routed to the given terminal T by power amplifier 52 and filter 56
of duplexer 54. Received signals in the downlink frequency range
for Band 13 may be routed from the given terminal T to receiver RX
by filter 58 and low noise amplifier 60. Other bands (e.g., other
LTE bands, GSM bands, etc.) may be handled using their own
respective transmitters 48, power amplifiers 52, receivers 50, low
noise amplifiers 60, and duplexer 54.
[0055] The transceiver circuitry for a first set of the frequency
bands handled by transceiver circuitry 38 (e.g., the lower
frequency bands) may be coupled to the terminals T of low band
switch 64LB. The transceiver circuitry for a second set of the
frequency bands handled by transceiver circuitry 38 (e.g., the
higher frequency bands) may be coupled to the terminals T of high
band switch 64HB. With one suitable arrangement, frequencies below
about 960 MHz may be handled by low band switch 64LB and
frequencies above about 1710 MHz may be handled by high band switch
64HB. Other configurations may be used in wireless circuitry 34 if
desired. These frequency assignments are merely illustrative.
[0056] Diplexer 68 may have filters FLB and FHB and ports
(terminals) PL, PH, and PA. Terminal T' of switch 64LB may be
coupled to port PL. Terminal T' of switch 64HB may be coupled to
port PH. Port PA of diplexer 68 may be coupled to antenna 40A.
Filter FLB may be a low pass filter. Filter FHB may be a high pass
filter or a bandpass filter. Diplexer 68 may use filters FLB and
FHB to route radio-frequency signals between switching circuitry 64
and antenna 40A according to frequency, while blocking undesired
signal harmonics.
[0057] FIG. 4 is a graph showing an illustrative radio-frequency
signal transmission characteristic that may be associated with
filter FLB. As shown in FIG. 4, filter FLB may be a low pass filter
that passes signals with frequencies f below frequency f1. The
value of f1 may be, for example, 960 MHz or other frequency that is
above the frequencies f.sub.LB1 . . . f.sub.LBN of the
communications bands that are being transmitted and received via
switch 64LB. Using low pass filter FLB, diplexer 68 may exhibit an
insertion loss of about 0.3 dB between ports PL and PA (i.e.,
maximum transmission value T2 of filter FLB may be about 0.3 dB
below 100% transmission level T1, as indicated by the gap between
100% transmission curve 70 and transmission curve 72 of filter
FLB.
[0058] FIG. 5 is a graph showing an illustrative radio-frequency
signal transmission characteristic that may be associated with
filter FHB. As shown in FIG. 5, filter FLB may be a high pass
filter (see, e.g., curve 76 and curve portion 80-2) or a bandpass
filter (see, e.g., curve 76 and curve portion 80-1) that passes
signals with frequencies f above frequency f2. The value of f2 may
be, for example, 1710 MHz or other frequency that is below the
frequencies f.sub.HB1 . . . f.sub.HBN of the communications bands
that are being transmitted and received via switch 64HB. Using high
pass filter (or bandpass filter) FLB, diplexer 68 may exhibit an
insertion loss of about 0.3 dB between ports PH and PA. As shown in
FIG. 5, for example, the maximum transmission value T2 of filter
FHB may be about 0.3 dB below 100% transmission level T1, as
indicated by the gap between 100% transmission curve 70 and
transmission curve 76 of filter FHB (diplexer 68). The insertion
losses associated with diplexer 68 may be somewhat higher or lower
than the illustrative 0.3 dB insertion loss shown in FIGS. 4 and 5.
Nevertheless, the insertion losses associated with use of a
diplexer such as diplexer 68 will generally be significantly less
than the insertion losses that would result if other types of
filtering circuitry such as notch filters were to be interposed
between switching circuitry 64 and antenna 40A.
[0059] Switching circuitry 64 may be implemented using switches 64A
and 64B that include gallium arsenide field-effect transistors
(FETs), microelectromechanical systems (MEMs) switches,
metal-oxide-semiconductor field-effect transistors (MOSFETs), p-i-n
diodes, high-electron mobility transistors (HEMTs), pseudomorphic
HEMI (PHEMTs), transistors formed on a silicon-on-insulator (SOI)
substrate, etc. When radio-frequency signals are transmitted from
transmitters 48 to antenna 40A, the transmitted signals pass
through switching circuitry 64. Nonlinearities in the behavior of
switching circuitry 64 may generate harmonics at terminals T'
(i.e., at the outputs of the switches). The filters of diplexer 68
can significantly attenuate these harmonics, so that the harmonics
are not transmitted through antenna 40A and are therefore not
received by antenna 40B. Because antenna 40B does not receive
harmonics of any significant magnitude, the receivers associated
with transceiver 46 (i.e., wireless local area network receiver
circuitry, satellite navigation receiver circuitry, etc.) will
operate properly without interference from the operation of
transceiver circuitry 38.
[0060] Consider, as an example, a situation in which the
communications bands that pass through low band switch 64LB and low
pass filter FLB (i.e., bands 74 at frequencies f.sub.LB1 . . .
f.sub.LBN of FIG. 4) are associated with LTE bands such as some or
all of Bands 5, 8, 17, 13, and 20 (and, if desired, other LTE bands
and/or other cellular telephone bands), whereas the communications
bands that pass through high band switch 64HB and high pass filter
(or bandpass filter) HLB (i.e., bands 78 at frequencies f.sub.HB1 .
. . f.sub.HBN of FIG. 5) are associated with LTE bands such as some
or all of Bands 4, 2, 7, 1, 3, and 40 (and, if desired, other LTE
bands and/or other cellular telephone bands). In a configuration of
this type, harmonics of some of the transmitted LTE bands may fall
within IEEE 802.11 (WiFi.RTM.) bands at 2.4 GHz and 5 GHz and/or
satellite navigation system bands such as the GPS band at 1575 MHz.
For example, the uplink (transmit) band associated with Band 13
extends from 777 MHz to 787 MHz. When Band 13 traffic is
transmitted by transceiver circuitry (e.g., transmitter TX of FIG.
3), switch 64LB may generate harmonics such as second harmonics in
the frequency range of 1554 MHz to 1574 MHz. If not attenuated by
diplexer 68, these second harmonics (particularly the harmonic
signals near 1574 MHz) might interfere with the GPS band centered
at 1575 MHz (i.e., the GPS receiver coupled to antenna 40A). By
using diplexer 68, however, the second harmonics in the frequency
range of 1554 MHz to 1574 MHz are attenuated significantly (e.g.,
by 15 dB or more, by 30 dB or more, etc.). As shown in FIG. 4, for
example, low pass filter FLB significantly attenuates signals at
frequencies above f1 (e.g., above 960 MHz or other suitable cutoff
frequency).
[0061] The third harmonics of LTE bands 1, 3, 4, and 2 may
represent a possible source of interference with the IEEE 802.11
wireless local area network band at 5 GHz. When signals in these
LTE bands are transmitted through switch 64HB, third harmonics in
the vicinity of 5 GHz may be produced. As indicated by curve 76
and, in particular, curve segment 80-1 of FIG. 5, when filter FHB
is implemented as a bandpass filter (i.e., when filter FHB passes
signals in a frequency range f2 to f3 of about 1710 MHz to 2.25
GHz), signals above 2.25 GHz (i.e., the harmonics in the vicinity
of 5 GHz) will be attenuated by filter FHB. As with the second
harmonics of Band 13 that are attenuated by filter FLB, these
harmonics will not reach antenna 40B. Because diplexer 68 prevents
transmitted signal harmonics from being transmitted through antenna
40B, these harmonics will not be received by antenna 40A, even when
antennas 40A and 40B are located within the same device (e.g., at
ends 44 and 42, respectively) and are potentially in close
proximity to each other (e.g., 15 cm or less apart, etc.).
[0062] If desired, the lower cutoff frequency f2 and upper cutoff
frequency f3 of high band filter FHB may be lower or higher to
accommodate different transmitted bands. If no receiver is used in
device 10 at 5 GHz, filter FHB may be implemented using a high pass
filter (i.e., filter with a low frequency cutoff such as frequency
f2 of FIG. 5, but no sharp upper frequency cutoff such as frequency
f3 so that curve 76 follows segment 80-2 above f3). Low band filter
FLB can be implemented using different cutoff frequencies. The use
of a 960 MHz cutoff frequency for frequency f1 of FIG. 1 is
presented as an example.
[0063] It may be desirable to simultaneously receive
radio-frequency transmissions in two different frequency bands. For
example, device 10 may communicate with a cellular base station
using a Long Term Evolution (LTE) protocol. In this type of
communications environment, a cellular base station may expect
device 10 to receive data using two different LTE communications
bands (sometimes referred to as carrier aggregation). As an
example, the base station may require device 10 to simultaneously
receive data on LTE band 4 and LTE band 17. To receive data on LTE
band 4, device 10 may be configured to accommodate frequencies from
2110 MHz to 2155 MHz. To receive data on LTE band 17, device 10 may
be configured to accommodate frequencies from 734 MHz to 746
MHz.
[0064] By receiving data using two different communications bands,
device 10 may be provided with increased bandwidth. For example, a
device 10 that simultaneously receives data streams in LTE band 4
and LTE band 17 may be provided with a communications bandwidth
equal to the combination of the respective bandwidths of LTE band 4
and LTE band 17 (e.g., 45 MHz from LTE band 4 added to 12 MHz from
LTE band 17). In this way, device 10 may be provided with improved
data transmissions rates.
[0065] In the illustrative embodiment of FIG. 6, device 10 has been
provided with wireless communications circuitry 34 that is
configured to simultaneously receive radio-frequency transmissions
in different frequency bands. The embodiment of FIG. 6 may
correspond to the wireless communications circuitry 34 of FIG. 3 in
which a single transmitter and two receivers are multiplexed with
switching circuitry (e.g., switching circuitry 102, 104, and 106)
to accommodate all communications bands.
[0066] As shown in FIG. 6, wireless communications circuitry 34 may
include an antenna such as antenna 40C that receives wireless
transmissions (e.g., from a cellular base station). The received
wireless transmission may be provided to diplexer 68 via diplexer
port PA. Diplexer 68 may include circuitry that routes signals
according to frequency. For example, diplexer 68 may have filters
FLB (e.g., a low pass filter) and FHB (e.g., a high pass filter)
that divide received wireless transmissions into low frequencies
and high frequencies, respectively, while minimizing signal loss
(e.g., while minimizing insertion loss). Received signals with low
frequencies may be routed to terminal T' of switch 64LB from
diplexer port PL. Received signals with high frequencies may be
routed to terminal T' of switch 64HB from diplexer port PH. During
signal transmission, low band signals at port PL and high band
signals at port PH may be combined by diplexer 68 and the resulting
combined signals may be output at port PA.
[0067] Switches 64LB and 64HB may each have one or more terminals
T. Switches 64LB and 64HB may be electrically controllable switches
(e.g., transistor-based switches) that may each be configured via
control terminals 62 to couple a selected one of terminals T to
terminal T'. Each terminal T of switches 64LB and 64HB may be
coupled to a respective one of duplexers 54. Duplexers 54 may each
have respective high and low band filters. For example, each
duplexer may have a first filter such as filter 56 and a second
filter such as filter 58. Filter 56 and filter 58 may separate
radio-frequency signals into separate frequency bands corresponding
to a transmit frequency bands and a receive frequency bands.
Filters 56 may isolate frequencies that correspond to transmit
(uplink) frequencies and provide the isolated frequencies to
switching circuit 102. Switching circuit 102 may be configurable
via control terminal 62 to couple transmitter TX to a desired
duplexer 54. Filters 58 may isolate frequencies that correspond to
receive (downlink) frequencies. By configuring the frequency
responses of filters 56 and 58, each duplexer 54 (and an associated
terminal T) may be configured to handle signals associated with a
particular communications band. For example, a first terminal T may
be associated with LTE band 4 and a second terminal T may be
associated with LTE band 17.
[0068] To simultaneously receive radio-frequency transmissions in
different frequency bands, filters 58 that are coupled to switch
64LB may be coupled to switching circuit 104 and filters 58 that
are coupled to switch 64HB may be coupled to switching circuit 106.
Switching circuitry 104 and 106 may be implemented using
electrically controllable switches (e.g., transistor-based
switches) that are configurable via control terminals 62. Switch
104 may be coupled to receiver RX1 and switch 106 may be coupled to
receiver RX2. Receiver RX1 may receive radio-frequency signals that
correspond to relatively low frequencies. Receiver RX2 may receive
radio-frequency signals that correspond to relatively high
frequencies.
[0069] As an example, a device 10 that communicates with a base
station using the LTE standard may simultaneously receive
radio-frequency transmissions in band 4 (e.g., a frequency band
that corresponds to relatively high frequencies) and band 17 (e.g.,
a frequency band that corresponds to relatively low frequencies).
In this scenario, the radio-frequency transmissions received by
device 10 via antenna 40C may be partitioned by diplexer 68 into
signals that correspond to band 4 and signals that correspond to
band 17.
[0070] The signals that correspond to band 4 may be received by
switch 64HB and forwarded to a first duplexer 54 that is configured
to accommodate the frequencies associated with band 4. The first
duplexer 54 may partition the frequencies associated with band 4
into a transmit band and a receive band (e.g., a transmit band
corresponding to 1710 MHz through 1755 MHz and a receive band
corresponding to 2110 MHz through 2155 MHz) and provide the signals
associated with the receive band to multiplexer 106 and receiver
RX2. Receiver RX2 may process the signals associated with the
receive band (e.g., receiver RX2 may demodulate the signals and
provide the signals to a baseband processor).
[0071] The signals that correspond to band 17 may be received by
switch 64LB and forwarded to a second duplexer 54 associated with
band 17. The second duplexer 54 may partition the frequencies
associated with band 17 into a transmit band and a receive band
(e.g., a transmit band corresponding to 704 MHz through 716 MHz and
a receive band corresponding to 734 MHz through 746 MHz) and
provide the signals associated with the receive band to multiplexer
104 and receiver RX1 for processing.
[0072] To allow receiver RX1 and RX2 to simultaneously receive
radio-frequency signals in different communications bands, each
receiver may be coupled to a respective local oscillator. Receiver
RX1 may be coupled to local oscillator LO1 and receiver RX2 may be
coupled to local oscillator LO2. Local oscillators LO1 and LO2 may
generate signals with appropriate frequencies (e.g., sinusoidal
signals or other desired signals with appropriate frequencies) for
receivers RX1 and RX2 to use for processing radio-frequency
signals. For example, receiver RX1 may receive radio-frequency
signals corresponding to LTE band 17. In this scenario, local
oscillator LO1 may be tuned to provide a signal with an appropriate
frequency for demodulating radio-frequency signals associated with
LTE band 17.
[0073] The use of two separate local oscillators LO1 and LO2 to
provide receivers RX1 and RX2 with respective signals is merely
illustrative. If desired, local oscillating circuitry 156 may
provide receivers RX1 and RX2 with two signals with different
frequencies. For example, local oscillating circuitry 156 may
include a single local oscillator configured to generate a first
signal at a first frequency and the first signal may be provided to
receiver RX1. Local oscillating circuitry 156 may also include
frequency dividing circuitry configured to use the first signal to
generate a second signal at a second frequency and the second
signal may be provided to receiver RX2.
[0074] In this way, radio-frequency transmissions that are received
by device 10 may be simultaneously processed. By simultaneously
processing two different frequency bands, device 10 may be provided
with increased communications bandwidth, thereby increasing data
rates.
[0075] The use of the circuitry of FIG. 6 to handle signals
associated with LTE bands 4 and 17 is merely illustrative. Any two
different communications bands may be simultaneously received by
configuring wireless communications circuitry 34 to accommodate the
desired frequency bands. For example, LTE band 2 may be
simultaneously received with LTE band 17, LTE band 5, the MediaFLO
band, or other desired frequency bands. As another example, LTE
band 4 may be simultaneously received with LTE band 5 or the
MediaFLO band, LTE band 1 may be simultaneously received with LTE
band 8 or with LTE band 20, LTE band 3 may be simultaneously
received with LTE band 8 or band 20, etc. If desired, more than two
frequency bands may be simultaneously handled in this way. For
example, multiple diplexers may be arranged in stages to divide
received radio-frequency signals into a desired number of frequency
bands that are processed by respective receivers.
[0076] Receivers RX1 and RX2 may be formed as part of transceiver
circuitry or as separate circuits. For example, receiver RX1 and/or
receiver RX2 may be combined with transmitter TX to form a
transceiver or may be implemented separately as distinct receiver
and transmitter circuits. If desired, a first optional transceiver
154 may be formed from the combination of receiver RX1 and
transmitter TX and a second optional transceiver 154 may be formed
from the combination of receiver RX2 and an additional transmitter
TX.
[0077] Receivers RX1 and RX2 and transmitter TX may be coupled to
baseband processor circuitry 152. Receivers RX1 and RX2 may process
radio-frequency signals received from switches 104 and 106 and
provide the processed radio-frequency signals to baseband processor
circuitry 152. For example, receiver RX1 may receive
radio-frequency signals corresponding to LTE band 17 and demodulate
the radio-frequency signals to form baseband signals. In this
scenario, the baseband signals may be processed by baseband
processor circuitry 152.
[0078] FIG. 7 is a graph showing illustrative bands of
radio-frequency signals that may be handled using the circuitry of
FIG. 6. In the example of FIG. 7, frequency band LB.sub.TX may
correspond to a low transmit frequency band such as 704-716 MHz for
LTE band 17 and LB.sub.RX may correspond to a low receive frequency
band such as 734-746 MHz for LTE band 17 (e.g., LB.sub.TX may
correspond to the transmit band of LTE band 17 and LB.sub.RX may
correspond to the receive band of LTE band 17). Frequency band
HB.sub.TXmay correspond to a high transmit frequency band such as
1710-1755 MHz for LTE band 4 and HB.sub.RX may correspond to a high
receive frequency band such as 2110-2155 MHz for LTE band 4 (e.g.,
HB.sub.TX may correspond to the transmit band of LTE band 4 and
HB.sub.RX may correspond to the receive band of LTE band 4).
[0079] Diplexer 68 may be configured to partition the
radio-frequency transmissions into a first signal partition of
frequencies below F1 and a second signal partition of frequencies
above F1 (e.g., filter FLB may be configured to provide the first
signal partition to switch 64LB and filter HLB may be configured to
provide the second signal partition to switch 64HB). Switch 64LB
may be configured to couple a first duplexer 54 associated with
frequency bands LB.sub.TX and LB.sub.RX to filter FLB. Switch 64HB
may be configured to couple a second duplexer 54 associated with
frequency bands HB.sub.TX and HB.sub.RX to filter HLB.
[0080] First duplexer 54 may be configured to isolate low transmit
band LB.sub.TX from low receive band LB.sub.RX (e.g., using filters
to isolate frequencies lower than F2 from frequencies higher than
F2). Second duplexer 54 may be configured to isolate high transmit
band HB.sub.TX from high receive band HB.sub.RX (e.g., using
filters to isolate frequencies lower than F3 from frequencies
higher than F3). Low receive band LB.sub.RX may be provided to a
first receiver RX1 and high receive band HB.sub.RX may be provided
to a second receiver RX2. In this way, two different frequency
bands may be simultaneously received and processed by wireless
communications circuitry 34.
[0081] To communicate in a carrier aggregation mode (e.g., to
communicate between a cellular base station and a wireless device
using simultaneous radio-frequency transmissions in different
communications bands), the steps of the illustrative flowchart of
FIG. 8 may be performed.
[0082] In step 202, a cellular base station and a wireless
electronic device 10 may prepare for carrier aggregation. For
example, a base station may prepare for transmission of multiple
data streams and instruct the wireless electronic device to prepare
for simultaneous receipt of multiple data streams in different
communications bands (e.g., the base station may instruct the
wireless electronic device to operate in a carrier aggregation
mode). The multiple data streams may be generated from dividing a
single source data stream into multiple portions. In response to
receiving instructions to prepare for simultaneous receipt of
multiple data streams, the wireless electronic device may configure
switches to make appropriate routing connections (e.g., the
switches may be configured to route each communications band to a
respective receiver).
[0083] In step 204, the base station may simultaneously transmit
multiple data streams on different communications bands to wireless
electronic device 10. For example, the base station may transmit a
first data stream on LTE band 17 and a second data stream on LTE
band 4.
[0084] In step 206, electronic device 10 may use multiplexing
circuitry such as diplexer 68 and duplexers 54 to divide
radio-frequency signals that are received from the base station
based on frequency. For example, electronic device 10 may use a
diplexer 68 to divide radio-frequency signals received by an
antenna 40C from a base station into relatively low frequencies and
relatively high frequencies. The relatively low frequencies may be
provided to a first switch 64LB that has been configured (e.g.,
configured during step 202) to route the relatively low frequencies
to a first duplexer 54. The relatively high frequencies may be
provided to a second switch 64HB and routed to a second duplexer
54. The first duplexer 54may isolate a first data stream from the
relatively low frequencies and provide the first data stream to
receiver RX1. The second duplexer 54 may isolate a second data
stream from the relatively high frequencies and provide the second
data stream to receiver RX2.
[0085] In step 208, electronic device 10 may simultaneously receive
the multiple data streams using multiple receivers. For example,
receiver RX1 may demodulate a first data stream and provide the
demodulated first data stream to the base station. Receiver RX2 may
demodulate a second data stream and provide the demodulated second
data stream to the base station.
[0086] In step 210, the base station may simultaneously receive the
demodulated first and second data streams and combine the
demodulated first and second data streams to reconstruct the single
source data stream.
[0087] As an example, a base station may prepare for transmission
of a first data stream on LTE band 4 and transmission of a second
data stream on LTE band 17. In this scenario, the base station may
instruct a wireless electronic device 10 to prepare for
simultaneous receipt of the first data stream in LTE band 4 and the
second data stream in LTE band 17. In response to the instruction
from the base station, wireless electronic device 10 may configure
switch 64LB to route low band signals received from diplexer 68 to
a first duplexer 54 associated with LTE band 17. Device 10 may
configure switch 64HB to route high band signals received from
diplexer 68 to a second duplexer 54 that is associated with LTE
band 4. First duplexer 54 may provide LTE band 17 signals to
receiver RX1 via switch 104. Second duplexer 54 may provide LTE
band 4 signals to receiver RX2 via switch 106. Receivers RX1 and
RX2 may simultaneously provide the LTE band 17 and LTE band 4 data
streams to baseband processor circuitry for processing.
[0088] The foregoing is merely illustrative of the principles of
this invention and various modifications can be made by those
skilled in the art without departing from the scope and spirit of
the invention. The foregoing embodiments may be implemented
individually or in any combination.
* * * * *