U.S. patent application number 14/577000 was filed with the patent office on 2016-05-12 for multi-band transceiver front-end architecture with reduced switch insertion loss.
The applicant listed for this patent is Entropic Communications, Inc.. Invention is credited to Carl De Ranter, Branislav Petrovic.
Application Number | 20160134566 14/577000 |
Document ID | / |
Family ID | 55913061 |
Filed Date | 2016-05-12 |
United States Patent
Application |
20160134566 |
Kind Code |
A1 |
De Ranter; Carl ; et
al. |
May 12, 2016 |
MULTI-BAND TRANSCEIVER FRONT-END ARCHITECTURE WITH REDUCED SWITCH
INSERTION LOSS
Abstract
A T/R and routing switch includes a plurality of banks of a
plurality of switches that can be individually switched into or out
of a transmit and receive circuit. A control module can be provided
to switch one of the switches into the circuit to connect one of a
receive signal path or a transmit signal path to one of a plurality
of communication links.
Inventors: |
De Ranter; Carl; (Bierbeek,
BE) ; Petrovic; Branislav; (La Jolla, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entropic Communications, Inc. |
San Diego |
CA |
US |
|
|
Family ID: |
55913061 |
Appl. No.: |
14/577000 |
Filed: |
December 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62076351 |
Nov 6, 2014 |
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Current U.S.
Class: |
370/392 |
Current CPC
Class: |
H04L 49/253 20130101;
H04B 1/006 20130101; H04L 5/14 20130101 |
International
Class: |
H04L 12/937 20060101
H04L012/937 |
Claims
1. A T/R and routing switch for a communication transceiver,
comprising; a first plurality of switches, each switch of the first
plurality of switches having an input terminal, an output terminal
and a control terminal, wherein the input terminals of each of the
first plurality of switches are electrically connected to one
another to form a common transmit signal path; a second plurality
of switches, each switch of the second plurality of switches having
an input terminal, an output terminal and a control terminal,
wherein the output terminals of each of the switches are
electrically connected to one another to form a common receive
signal path; a plurality of interconnects, each interconnect
connecting an output terminal of one of the first plurality of
switches with an input terminal of one of the second plurality of
switches to form an input/output link for interconnected pairs of
switches; and a plurality of communication link terminals, each
communication link terminal electrically connected to one of the
input/output links.
2. The T/R and routing switch of claim 1, wherein the T/R and
routing switch is configurable such that only a single one of the
first and second plurality of switches is inserted in-line to
perform front-end routing of either a transmit or a receive signal
between a transmitter or receiver of the communication transceiver
and one of a plurality communication links over which the
communication transceiver communicates.
3. The T/R and routing switch of claim 1, further comprising a
controller configured to actuate one of the plurality of switches
to electrically connect one of a transmit and a receive signal path
of a communication transceiver to one of a plurality of
communication links.
4. The T/R and routing switch of claim 1, further comprising a
controller configured to actuate one of the plurality of switches
to electrically connect one of a transmit and a receive signal path
of a communication transceiver to one of a plurality of
communication links using only a single switch of the T/R and
routing switch.
5. The T/R and routing switch of claim 4, wherein each switch of
the first and second plurality of switches comprises a
transistor.
6. The T/R and routing switch of claim 5, further comprising
inductive elements configured to reduce an off capacitance of the
plurality of transistors that are not turned on.
7. The T/R and routing switch of claim 6, wherein the inductive
elements comprise an inductor connected in series with the transmit
signal path.
8. The T/R and routing switch of claim 6, wherein the inductive
elements comprise an inductive element connected between the common
receive signal path and ground.
9. The T/R and routing switch of claim 6, wherein the inductive
elements comprise a plurality of inductors and a third plurality of
switches each switch connected between one of the inductors and one
of the first and second plurality switches.
10. The T/R and routing switch of claim 9, wherein the controller
is further configured to control the third plurality of switches to
select a subset of at least one of the plurality of inductors to
tune the bandwidth of at least one of the first and second
plurality of switches.
11. The T/R and routing switch of claim 1, further comprising one
or more additional pluralities of switches each of the additional
pluralities of switches configured to control one or more
additional transmit signal paths and receive signal paths.
12. A front-end signal routing switch for use with a communication
transceiver comprising: a first plurality of switches each having a
common terminal configured to be connected to a transmit signal
path of the communication transceiver; and a second plurality of
switches each having a common terminal configured to be connected
to a receive signal path of the communication transceiver; wherein
the signal routing and switching front and is configured such that
only one of the switches of the first plurality of switches is
electrically present in the transmit signal path during transmit
operations of the communication transceiver, and only one of the
switches of the second plurality of switches is electrically
present in the receive signal path during receive operations of the
communication transceiver.
13. The front-end signal routing switch of claim 12, further
comprising a control module having a plurality of output ports,
each output port being electrically connected to one of the
switches of the first and second plurality of switches.
14. The front-end signal routing switch of claim 13, wherein each
switch of the first and second plurality of switches comprises a
transistor.
15. The front-end signal routing switch of claim 14, further
comprising inductive elements configured to reduce an off
capacitance of the plurality of transistors that are not turned
on.
16. The front-end signal routing switch of claim 15, wherein the
inductive elements comprise an inductor connected in series with
the transmit signal path.
17. The front-end signal routing switch of claim 15, wherein the
inductive elements comprise an inductive element connected between
the common receive signal path and ground.
18. The front-end signal routing switch of claim 15, wherein the
inductive elements comprise a plurality of inductors and a third
plurality of switches each switch connected between one of the
inductors and one of the first and second plurality switches.
19. The front-end signal routing switch of claim 18, wherein the
controller is further configured to control the third plurality of
switches to select a subset of at least one of the plurality of
inductors to tune the bandwidth of at least one of the first and
second plurality of switches.
20. The front-end signal routing switch of claim 12, wherein the
communication transceiver is a TDD transceiver.
21. A communication front-end, comprising: a communication
transceiver comprising a transmitter and a receiver; a plurality of
communication links, each communication link comprising an antenna
configured to transmit or receive communication signals; T/R and
routing switch comprising a first terminal communicatively coupled
to the transmitter and a second terminal communicatively coupled to
the receiver and a plurality of third terminals, each
communicatively coupled to one of the plurality of communication
links, the T/R and routing switch further comprising; a first
plurality of switches, each switch of the first plurality of
switches having an input terminal, an output terminal and a control
terminal, wherein the input terminals of each of the first
plurality of switches are electrically connected to the first
terminal; a second plurality of switches, each switch of the second
plurality of switches having an input terminal, an output terminal
and a control terminal, wherein the output terminals of each of the
switches are electrically connected to the second terminal; a
plurality of interconnects, each interconnect connecting an output
terminal of one of the first plurality of switches with an input
terminal of one of the second plurality of switches hand with one
of the plurality of third terminals.
22. The communication front end of claim 21, wherein only a single
switch of the T/R and routing switch is used to route a transmit or
a receive signal between the communication transceiver and one of
the communication links.
23. The communication front-end of claim 21, wherein the T/R and
routing switch is configurable such that only a single one of the
first and second plurality of switches is inserted in-line to
perform front-end routing of either a transmit or a receive signal
between the transmitter or the receiver of the communication
transceiver and one of the plurality communication links.
24. The communication front-end of claim 21, further comprising a
controller configured to actuate one of the plurality of switches
to electrically connect one of a transmit and a receive signal path
of a communication transceiver to one of a plurality of
communication links.
25. The communication front-end of claim 21, wherein each switch of
the first and second plurality of switches comprises a
transistor.
26. The communication front-end of claim 21, wherein the
communication transceiver is a TDD transceiver.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to co-pending U.S.
Provisional Application No. 62/076,351, filed on Nov. 6, 2014,
which is incorporated by reference herein in its entirety.
TECHNICAL FIELD
[0002] The disclosed technology relates generally to communication
systems, and more particularly, some embodiments relate to low
insertion loss switches for communication transceivers.
DESCRIPTION OF THE RELATED ART
[0003] Duplex communications generally refers to communications in
two directions--e.g., in the transmit and receive directions. Time
Division Duplex (TDD) schemes generally separate in time the
transmit and receive signals over a given communication link. TDD
can be used, for example, to emulate full duplex communications
over a half-duplex communication link.
[0004] The application of TDD generally involves a transmit/receive
switch (T/R switch) such that the transmitter and a receiver of a
given transceiver can be alternatively switched for communication
over the subject communication link. In some applications, the T/R
switch can be combined in conjunction with a routing switch to
allow the TDD communications to be routed over a selected one of a
plurality of communication links. That is, in many applications,
the T/R switch and a multi-throw routing switch used to realize the
switching between different bands (diplexers or antennas) are
implemented as separate entities, connected in series.
[0005] FIG. 1 is a diagram illustrating one example of such a
cascaded switch 103. This example includes a T/R switch 108
cascaded with a routing switch 105 to allow routing of the TDD
communications. In this example, transmit signals 109 or receive
signals 110 can be selected by T/R switch 108. One of a plurality
of communication links 104 (four shown) can be selected by routing
switch 105. The communication links 104 can be used, for example,
for communications at different frequency bands, or for different
antennas, or both.
[0006] Accordingly, cascaded switch 103 allows routing of TDD
signals to/from any of these communication links 104. However,
switches generally introduce an insertion loss and some level of
distortion into the communication path. In instances where two
switches are cascaded, such as with cascaded switch 103, the
insertion loss and distortion introduced by both switches affects
the communication link.
BRIEF SUMMARY OF EMBODIMENTS
[0007] According to various embodiments of the disclosed technology
a T/R switch for communication transceivers is provided. More
particularly, some embodiments relate to a switch configuration
that can be used with a transceiver front-end to provide T/R
switching and band or antenna switching. Embodiments can be
implemented in which a single switch is inserted in-line with the
communication path selected between one of the transmitter and
receiver, and one of the communication links. In various
embodiments, each band may be implemented to include its own
matching network and/or diplexer such as, for example, with a MoCA
multi-band adapter.
[0008] In various embodiments, the transceiver front-end switch can
be implemented in a single die. By integrating the functionality of
the T/R switch and the multi-throw routing switch in one (small)
die, the optimal technology can be chosen to enable stacked-device
switches that allow the large single-ended voltages as required by
cellular, wireless or wireline transmit/receive standards (as GSM,
WiFi, MoCA, etc.), without a big impact on the overall BOM (Bill of
Materials) cost.
[0009] Embodiments can be implemented in which some or all of the
following advantages can be realized. In some embodiments,
implementations can be accomplished with lower required Pout,max
for the line driver/power amplifier (transmit path) for a given
required output power at the antenna or connector. Various
embodiments may achieve better sensitivity for the receive path for
a given noise figure (NF) of the low noise amplifier (LNA). Because
the LNA NF is, in practice, generally optimized in most
applications, this may be the only way that input sensitivity can
be increased or maximized. Additionally, embodiments can be
implemented to achieve an overall lower power consumption due to
lower required Pout,max and possibly relaxed (higher allowable)
NF.
[0010] According to an embodiment of the disclosed technology a T/R
and routing switch for a communication transceiver, includes; a
first plurality of switches, each switch of the first plurality of
switches having an input terminal, an output terminal and a control
terminal, wherein the input terminals of each of the first
plurality of switches are electrically connected to one another to
form a common transmit signal path; a second plurality of switches,
each switch of the second plurality of switches having an input
terminal, an output terminal and a control terminal, wherein the
output terminals of each of the switches are electrically connected
to one another to form a common receive signal path; a plurality of
interconnects, each interconnect connecting an output terminal of
one of the first plurality of switches with an input terminal of
one of the second plurality of switches to form an input/output
link for interconnected pairs of switches; and a plurality of
communication link terminals, each communication link terminal
electrically connected to one of the input/output links.
[0011] The T/R and routing switch may be configurable such that
only a single one of the first and second plurality of switches is
inserted in-line to perform front-end routing of either a transmit
or a receive signal between a transmitter or receiver of the
communication transceiver and one of a plurality communication
links over which the communication transceiver communicates.
[0012] A controller can be included and configured to actuate one
of the plurality of switches to electrically connect one of a
transmit and a receive signal path of a communication transceiver
to one of a plurality of communication links. This can be done so
that only a single switch of the T/R and routing switch is in line
between the transceiver and the selected communication link.
[0013] In various embodiments, the T/R and routing switch may
further include inductive elements, such as inductors, configured
to reduce an off capacitance of the plurality of transistors that
are not turned on. Inductive elements may be connected in series
with the transmit signal path. Inductive elements may also be
connected between the common receive signal path and ground. In
some embodiments, the inductive elements comprise a plurality of
inductors and a third plurality of switches each switch connected
between one of the inductors and one of the first and second
plurality switches.
[0014] The controller may further be configured to control the
third plurality of switches to select a subset of at least one of
the plurality of inductors to tune the bandwidth of at least one of
the first and second plurality of switches.
[0015] The T/R and routing switch may also include one or more
additional pluralities of switches each of the additional
pluralities of switches configured to control one or more
additional transmit signal paths and receive signal paths.
[0016] In accordance with another embodiment, a front-end signal
routing switch for use with a communication transceiver may
include: a first plurality of switches each having a common
terminal configured to be connected to a transmit signal path of
the communication transceiver; and a second plurality of switches
each having a common terminal configured to be connected to a
receive signal path of the communication transceiver; wherein the
signal routing and switching front and is configured such that only
one of the switches of the first plurality of switches is
electrically present in the transmit signal path during transmit
operations of the communication transceiver, and only one of the
switches of the second plurality of switches is electrically
present in the receive signal path during receive operations of the
communication transceiver. A control module having a plurality of
output ports can be included, and each output port may be
electrically connected to one of the switches of the first and
second plurality of switches.
[0017] Inductive elements such as, for example, inductors, can be
included and configured to reduce an off capacitance of the
plurality of switches (e.g., transistors) that are not turned on.
The inductive elements may include an inductor connected in series
with the transmit signal path. The inductive elements may include
an inductive element connected between the common receive signal
path and ground. In other embodiments, the inductive elements may
include a plurality of inductors and a third plurality of switches
each switch connected between one of the inductors and one of the
first and second plurality switches. The controller may be further
configured to control the third plurality of switches to select a
subset of at least one of the plurality of inductors to tune the
bandwidth of at least one of the first and second plurality of
switches.
[0018] A communication front-end, may include: a communication
transceiver comprising a transmitter and a receiver; a plurality of
communication links, each communication link comprising an antenna
configured to transmit or receive communication signals; a T/R and
routing switch comprising a first terminal communicatively coupled
to the transmitter and a second terminal communicatively coupled to
the receiver and a plurality of third terminals, each
communicatively coupled to one of the plurality of communication
links, the T/R and routing switch further comprising; a first
plurality of switches, each switch of the first plurality of
switches having an input terminal, an output terminal and a control
terminal, wherein the input terminals of each of the first
plurality of switches are electrically connected to the first
terminal; a second plurality of switches, each switch of the second
plurality of switches having an input terminal, an output terminal
and a control terminal, wherein the output terminals of each of the
switches are electrically connected to the second terminal; a
plurality of interconnects, each interconnect connecting an output
terminal of one of the first plurality of switches with an input
terminal of one of the second plurality of switches hand with one
of the plurality of third terminals. In various embodiments, the
system can be configured such that only a single switch of the T/R
and routing switch is used to route a transmit or a receive signal
between the communication transceiver and one of the communication
links. In further embodiments, the system can be configured such
that only a single one of the first and second plurality of
switches is inserted in-line to perform front-end routing of either
a transmit or a receive signal between the transmitter or the
receiver of the communication transceiver and one of the plurality
communication links.
[0019] A controller may be included and configured to actuate one
of the plurality of switches to electrically connect one of a
transmit and a receive signal path of a communication transceiver
to one of a plurality of communication links.
[0020] In various embodiments, the switches may comprise a
transistor and the communication transceiver may comprise a TDD
transceiver.
[0021] Other features and aspects of the disclosed technology will
become apparent from the following detailed description, taken in
conjunction with the accompanying drawings, which illustrate, by
way of example, the features in accordance with embodiments of the
disclosed technology. The summary is not intended to limit the
scope of any inventions described herein, which are defined solely
by the claims attached hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The technology disclosed herein, in accordance with one or
more various embodiments, is described in detail with reference to
the following figures. The drawings are provided for purposes of
illustration only and merely depict typical or example embodiments
of the disclosed technology. These drawings are provided to
facilitate the reader's understanding of the disclosed technology
and shall not be considered limiting of the breadth, scope, or
applicability thereof. It should be noted that for clarity and ease
of illustration these drawings are not necessarily made to
scale.
[0023] FIG. 1 is a diagram illustrating one example of a
conventional cascaded switch.
[0024] FIG. 2 is a diagram illustrating an example of a wideband
transceiver with a low insertion loss T/R and routing switch in
accordance with one embodiment of the technology disclosed
herein.
[0025] FIG. 3 is a diagram illustrating an example of a front-end
switch 212 in accordance with one embodiment of the technology
disclosed herein.
[0026] FIG. 4 is a diagram illustrating an example implementation
of the front-end switch of FIG. 3 in accordance with one embodiment
of the technology disclosed herein.
[0027] FIG. 5 is a diagram illustrating an example of adding
inductance to reduce the effect of capacitance for the
switches.
[0028] FIG. 6 is a diagram illustrating an example in which a
front-end switch (e.g., such as that depicted in FIGS. 3 and 4) is
implemented with a communication transceiver in accordance with one
embodiment of the technology disclosed herein.
[0029] The figures are not intended to be exhaustive or to limit
the invention to the precise form disclosed. It should be
understood that the invention can be practiced with modification
and alteration, and that the disclosed technology be limited only
by the claims and the equivalents thereof.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0030] Embodiments of the technology disclosed herein are directed
toward devices and methods for providing T/R and routing switching
with reduced insertion loss as compared to conventional cascaded
switches. Embodiments can be provided in which a single switch is
inserted in-line with the communication path selected between one
of the transmitter and receiver, and one of the communication
links.
[0031] Before describing the technology in detail, it is useful to
describe an example environment with which embodiments can be
implemented. FIG. 2 is a diagram illustrating an example of a
wideband transceiver with a low insertion loss T/R and routing
switch in accordance with one embodiment of the technology
disclosed herein. This example includes a communication transceiver
288, a front-end switch 212, and a plurality of communication links
204. In some embodiments, some or all of the communication links
204 can be implemented as operating at different frequencies.
Accordingly, front-end switch 212 can be implemented to select from
among the transmit and receive lines (e.g. in a TDD fashion) and to
select the appropriate communication link 204 for transmission or
reception.
[0032] As seen in this example, communication transceiver 288 is
provided with both transmit and receive capabilities. Communication
transceiver 288 can be implemented, for example, as a
system-on-a-chip (SOC) transceiver. This example includes baseband
processing 279 to perform communication functions in the digital
domain. One example of the communication transceiver 288 is a MoCA
SOC transceiver, although other transceivers can be used for other
communication protocols and standards.
[0033] On the receive communication path, a received signal from
one of the antennas 205 is switched to the receive signal path 210
by front-end switch 212. The matching network and/or filter 286 can
be included in the receive signal path. A variable gain amplifier
VGA 312 can be provided to adjust the level of the incoming signal
to provide the appropriate signal strength. An analog-to-digital
converter 314 is provided to digitize the received signal for
baseband processing.
[0034] On the transmit side, a digital-to-analog converter 413 is
provided to digitize the outgoing signal received from baseband
processing 279. A variable gain amplifier 412, and a power
amplifier 414 can be provided to drive the output signal. A
matching network and/or filter 285 can be included in the transmit
signal path 209. Although not illustrated, a balun may also be
included. Front-end switch 212 switches the transmit signal from
transmit signal path 209 to a selected one of the antennas 205.
[0035] FIG. 3 is a diagram illustrating an example of a front-end
switch 212 in accordance with one embodiment of the technology
disclosed herein. In this example, a plurality of switches 303 are
provided (only two switches include reference characters in the
figure to avoid clutter). A first bank 207 of switches 303 is
connected to interface with transmit signal path 209, while a
second bank 208 of switches 303 is configured to interface with
receive signal path 210.
[0036] Each switch 303 in both banks of switches 207, 208 has an
input terminal, an output terminal and a control line. The input
terminals for switches 303 in the first bank 207 are electrically
connected to one another to form a transmit signal path that can be
electrically connected to the transmit signal path of the
transmitter side of the transceiver (e.g., communication
transceiver 288). This electrical connection to the transmitter can
be made, as illustrated in this example, via one of the terminals
214. The output terminals for switches 303 in first bank 207 are
electrically connected to a plurality of parallel communication
paths that, in this example, are electrically connected to
corresponding communication link terminals 213. The output
terminals of switches 303 in first bank 207 are also electrically
connected to the input terminals of switches 303 in second bank 208
(which are also electrically connected to corresponding
communication link terminals 213). The output terminals of switches
303 in second bank 208 are electrically connected to one another to
form a received signal path that can be electrically connected to
the receive signal path of the receiver side of the transceiver
(e.g., communication transceiver 288). This electrical connection
to the receiver can be made, as illustrated in this example, via
the other one of the terminals 214.
[0037] As seen from this illustration, the front-and switch can be
implemented to effectively perform a parallel-to-serial or
serial-to-parallel conversion for the receive and transmit sides
respectively. That is, a transmitted signal received by the
front-end switch 212 via transmit signal path 209 can be received
on a single line and directed to one of a plurality of effectively
parallel communication links at the outputs of the first bank 207
of switches 303. Likewise, receive signals received on one of the
plurality of effectively parallel communication links can be
switched by second bank 208 onto the single receive signal path
210.
[0038] In this example, there are four possible communication links
204 that can be switched to the transmitter or receiver. Each of
these communication links is connected to an input of the
corresponding switch 303 of second bank 208, and each of the
communication links 204 is also connected to an output of its
corresponding switch 303 of first bank 207. As will be apparent to
one of ordinary skill in the art after reading this description, a
front-end switch 212 can be implemented to interface with any of a
number of communication links 204 and any of a number of transmit
and receive paths.
[0039] This example also illustrates a controller 244 that can be
used to control front-end switch 212. In operation, when the system
is operating in the receive mode, it is desirable to switch a
received signal from the appropriate communication link 204 to
receive signal path 210. Accordingly, one of switches 303 in second
bank 208 is actuated, or closed, to couple the corresponding
communication link 204 to receive signal path 210. This operation
can be undertaken by controller 244, which may be configured to
send a control signal to the selected switch 303 to close, or
actuate, the switch and complete the signal path between the
designated communication link 204 and receive signal path 210.
Similarly, for transmit operations, the appropriate switch 303 in
first bank 207 of switches 303 is closed to electrically connect
transmit signal path 209 to the corresponding one of the
communication links 204. This can be done by controller 244 sending
the appropriate control signal to actuate the selected switch 303
for the desired connection.
[0040] FIG. 4 is a diagram illustrating an example implementation
of the front-end switch of FIG. 3 in accordance with one embodiment
of the technology disclosed herein. In this example, the first and
second banks of switches 207, 208 are implemented as a plurality of
transistors that can be controlled by controller 244. Depending on
the implementation, the transistors can be implemented as CMOS,
MOSFET, MESFET, JFET, BJT, for example. After reading this
description, one of ordinary skill in the art will understand how
other transistor types can be used. Likewise, other switches or
relays can be used.
[0041] In operation, controller 244 effectively closes the switch
by turning the appropriate corresponding transistor on. This can be
accomplished, for example, by applying an appropriate voltage to
that transistor. In the illustrated embodiment, the appropriate
turn-on voltage can be applied to the gate of the transistor by
controller 244, thereby electrically connecting the source and the
drain of that transistor. The other transistors can remain open, or
off, by grounding, floating, or simply not providing a turn-on
voltage to those transistors.
[0042] As noted above, one goal of certain embodiments may be to
reduce the insertion loss introduced by the switch. One way in
which a lower insertion loss can be achieved is by using larger
transistors. However, larger transistors also lead to a larger
capacitance introduced into the circuit when the transistors are in
the off state. Accordingly, embodiments can be implemented to
optimize the balance between the on performance and the off
performance of the switches. In some embodiments, a decrease in the
size of the transistor can lead to a relatively small decrease in
the on performance of the switch (e.g. a minimal increase for the
insertion loss) and a relatively larger increase in off performance
(e.g. a reduction in off capacitance, leading to a reduction in
loading and noise).
[0043] Additionally, in further embodiments, parasitic capacitance
introduced by the transistors can be tuned out by, for example,
adding inductive elements into the circuit. However, the addition
of inductive elements can have the effect of narrowing the
bandwidth of the switches. The narrowing of the bandwidth may be
acceptable in some applications where the bandwidth of the switch
coincides with the communication band or bands of the transmitter
and receiver. Therefore, in some embodiments, different elements at
different inductance values can be provided and selectively
switched into and out of the circuit. Accordingly, embodiments can
be implemented to eliminate or reduce capacitance of the off state,
while reducing or minimizing negative repercussions caused by the
narrowed bandwidth by tuning the switches for the desired band of
operation.
[0044] In various embodiments, controller 244 can further be
configured to control switches (e.g., transistors or other
switches) to switch different inductance values into and out of the
circuit for tuning purposes. In some embodiments, controller 244
can be configured to accept as input, information identifying the
selected band at which the system is operating, and to switch the
appropriate tuning elements into and out of the circuit to tune the
switches for the operating frequency. Accordingly, capacitance of
the switches in the off state can be reduced using inductive
elements, and the bandwidth of switches can be tuned to the
operating frequency. In other embodiments, manual tuning can be
provided by providing user selectable switches such as, for
example, physical switches that can be set by the user, or
programmable switches that can be controlled through a user
interface. In further embodiments, the frequency detection module
can be provided to sense the frequency of the communication links.
The sensed frequency can be fed to controller 244 so that
controller 244 may tune the switches accordingly. In applications
where the system may be operating at one of a variety of predefined
frequencies or channels, there can be a limited number of tuning
configurations to tune to the possible channels. Where there are a
limited quantity of known frequencies or channels, the system can
be simplified accordingly.
[0045] FIG. 5 is a diagram illustrating an example of adding
inductance to reduce the effect of capacitance for the switches. In
the first example, the inductance is added in parallel to the
capacitance of the switch. In this example, resistor 452 represents
the on resistance of the switch R.sub.ON. Capacitance 454
represents the capacitance introduced by the switch in the off
position. In the case of x number of switches, the total
capacitance C.sub.TOT introduced by the switches in the off state
is (x-1) times the off capacitance C.sub.OFF of the switches. In
other words C.sub.TOT=(x-1).times.C.sub.OFF. From this, the
resonant frequency can be determined as
f R = 1 2 .pi. LC TOT . ##EQU00001##
[0046] This equation can be used so that the inductance, L, can be
selected to tune the bandwidth to the desired operating band.
Another example illustrated in the lower half of FIG. 5 shows a
series inductance used to tune the bandwidth of the circuit. In
this example, inductor 456 is provided in series with the on
resistance of the switch 453. Capacitance 455 represents the
capacitance introduced by the switch in the off position. While the
example in the upper half of FIG. 5 illustrates a bandpass filter,
the example of lower half of FIG. 5 illustrates a low pass
filter.
[0047] In embodiments where the inductance is added to create a
bandpass filter, (i.e. the inductance is added in parallel with the
capacitance) a tuning inductor can be included, for example,
between receive signal line 210 and ground. Placing the inductance
here, as opposed to one the other side of the switches, can allow
the tuning to be accomplished with only one inductor (or only one
inductor for each frequency in the embodiments where the bandwidth
can be selectively tuned) for the entire bank. Similarly, for a low
pass filter implementation a single inductor can be provided in
series in transmit signal path 209 to provide the series inductance
for each of the switches in first switch bank 207. This can be
advantageous over providing an inductor at the output of each
switch in first switch bank 207.
[0048] In both examples illustrated in FIGS. 3 and 4, four
communication links 204 are interfaced to two transceiver
lines--i.e., a transmit and receive line. As noted above, the
front-end switch 212 can be scaled to accommodate any quantity of
communication links, and can also be scaled to handle more than one
each of a transmit and a receive signal path. Where there is one
transmit and one receive signal path (i.e., two paths), 2n switches
(e.g. switches 303) are used to interface to n number of
communication links. As a further example, where there are m
transmit and receive signal paths in total and n communication
links, selectability of all possible permutations can be
accomplished by providing m*n switches.
[0049] As these examples illustrate, there is one bank of switches
for each transmit or receive line to be selected, and the number of
switches in each bank corresponds to the number of possible
communication links with which that bank (particularly, its
corresponding transmit or receive signal path) may be coupled. In
the illustrated example, each transmit and receive signal path can
be selectively coupled to any one of the available communication
links. However, in alternative embodiments, configurations can be
implemented such that one or more of the transmit or receive signal
paths can be coupled to fewer than all of the available
communication links.
[0050] As the above examples illustrate, regardless of the
communication link selected, and regardless of whether the system
is operating in the transmit or the receive mode, embodiments may
be implemented in which only one switch is inserted into the signal
path to handle this front-end switching. This is in contrast to
conventional solutions (e.g. as shown in FIG. 1) in which two
switches are required in series to handle the switching.
Accordingly, embodiments may be implemented in which the insertion
loss and/or distortion for the front-end switch are lower than that
which may otherwise be achieved with cascaded T/R and routing
switches in conventional solutions.
[0051] In various embodiments, the layout of the front-end switch
212 can be implemented to provide isolation between the various
signal paths to avoid crosstalk or other interference. For example,
in various embodiments, the signal paths can be laid out orthogonal
to one another or with sufficient spacing between one another to
avoid crosstalk interference. This can depend, for example, on the
isolation requirements specified for the switches for a given
application.
[0052] Switch array, and in some embodiments the controller, can be
implemented on a single die as a standalone unit, or it can be
integrated with the transceiver. In some embodiments, the switch
array die can be implemented using thick film 0.18 .mu.m SOI. Some
embodiments can include a low noise amplifier on the receive path
to overcome noise spurs at the receive input pin of the
transceiver. This may be particularly useful where a single-ended
implementation is chosen.
[0053] FIG. 6 is a diagram illustrating an example in which a
front-end switch 212 (e.g., such as that depicted in FIGS. 3 and 4)
is implemented with a communication transceiver 288 in accordance
with one embodiment of the technology disclosed herein. As seen in
this example, one bank of the front-end switch 212 is interfaced
with transmit signal path 209 and another bank of front-end switch
212 is interfaced with receive signal path 210.
[0054] Controller 244 in various embodiments may be implemented
utilizing any form of hardware, software, or a combination thereof.
For example, one or more processors, controllers, ASICs, PLAs,
PALs, CPLDs, FPGAs, logical components, software routines or other
mechanisms might be implemented to make up a module. Controller 244
may include or have access to a non-transitory storage medium with
computer program code or other like instructions embodied thereon
configured to cause a processing device of the controller (e.g.,
one or more processors) to perform the described functions.
[0055] While various embodiments of the disclosed technology have
been described above, it should be understood that they have been
presented by way of example only, and not of limitation. Likewise,
the various diagrams may depict an example architectural or other
configuration for the disclosed technology, which is done to aid in
understanding the features and functionality that can be included
in the disclosed technology. The disclosed technology is not
restricted to the illustrated example architectures or
configurations, but the desired features can be implemented using a
variety of alternative architectures and configurations. Indeed, it
will be apparent to one of skill in the art how alternative
functional, logical or physical partitioning and configurations can
be implemented to implement the desired features of the technology
disclosed herein. Also, a multitude of different constituent module
names other than those depicted herein can be applied to the
various partitions. Additionally, with regard to flow diagrams,
operational descriptions and method claims, the order in which the
steps are presented herein shall not mandate that various
embodiments be implemented to perform the recited functionality in
the same order unless the context dictates otherwise.
[0056] Although the disclosed technology is described above in
terms of various exemplary embodiments and implementations, it
should be understood that the various features, aspects and
functionality described in one or more of the individual
embodiments are not limited in their applicability to the
particular embodiment with which they are described, but instead
can be applied, alone or in various combinations, to one or more of
the other embodiments of the disclosed technology, whether or not
such embodiments are described and whether or not such features are
presented as being a part of a described embodiment. Thus, the
breadth and scope of the technology disclosed herein should not be
limited by any of the above-described exemplary embodiments.
[0057] Terms and phrases used in this document, and variations
thereof, unless otherwise expressly stated, should be construed as
open ended as opposed to limiting. As examples of the foregoing:
the term "including" should be read as meaning "including, without
limitation" or the like; the term "example" is used to provide
exemplary instances of the item in discussion, not an exhaustive or
limiting list thereof; the terms "a" or "an" should be read as
meaning "at least one," "one or more" or the like; and adjectives
such as "conventional," "traditional," "normal," "standard,"
"known" and terms of similar meaning should not be construed as
limiting the item described to a given time period or to an item
available as of a given time, but instead should be read to
encompass conventional, traditional, normal, or standard
technologies that may be available or known now or at any time in
the future. Likewise, where this document refers to technologies
that would be apparent or known to one of ordinary skill in the
art, such technologies encompass those apparent or known to the
skilled artisan now or at any time in the future.
[0058] The presence of broadening words and phrases such as "one or
more," "at least," "but not limited to" or other like phrases in
some instances shall not be read to mean that the narrower case is
intended or required in instances where such broadening phrases may
be absent. The use of the term "module" does not imply that the
components or functionality described or claimed as part of the
module are all configured in a common package. Indeed, any or all
of the various components of a module, whether control logic or
other components, can be combined in a single package or separately
maintained and can further be distributed in multiple groupings or
packages or across multiple locations.
[0059] Additionally, the various embodiments set forth herein are
described in terms of exemplary block diagrams, flow charts and
other illustrations. As will become apparent to one of ordinary
skill in the art after reading this document, the illustrated
embodiments and their various alternatives can be implemented
without confinement to the illustrated examples. For example, block
diagrams and their accompanying description should not be construed
as mandating a particular architecture or configuration.
* * * * *