U.S. patent application number 12/618812 was filed with the patent office on 2011-05-19 for multiband rf device.
Invention is credited to Bernd Adler, Oluf Bagger, Mikael Bergholz Knudsen, Michael Wilhelm.
Application Number | 20110117862 12/618812 |
Document ID | / |
Family ID | 44011646 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110117862 |
Kind Code |
A1 |
Bagger; Oluf ; et
al. |
May 19, 2011 |
Multiband RF Device
Abstract
A device or system for transmission and reception for voice or
data communication applications. The device or system is capable of
duplex operation and adapted to operate in an environment using a
plurality of frequency bands. The present disclosure also relates
to a communication means including a transmitter and receiver
arrangement and to antennas.
Inventors: |
Bagger; Oluf; (Aalborg,
DK) ; Adler; Bernd; (Neubiberg, DE) ; Knudsen;
Mikael Bergholz; (Gistrup, DK) ; Wilhelm;
Michael; (Mammendorf, DE) |
Family ID: |
44011646 |
Appl. No.: |
12/618812 |
Filed: |
November 16, 2009 |
Current U.S.
Class: |
455/77 |
Current CPC
Class: |
H03F 2200/451 20130101;
H03F 3/19 20130101; H04B 2001/0416 20130101; H04L 5/14 20130101;
H04B 1/58 20130101; H04B 1/04 20130101; H04L 27/12 20130101; H04B
1/0057 20130101; H03F 2200/171 20130101; H03F 3/21 20130101; H03G
3/3042 20130101 |
Class at
Publication: |
455/77 |
International
Class: |
H04B 1/40 20060101
H04B001/40 |
Claims
1. A device for signal transmission, adapted for operation in a
plurality of frequency bands, comprising: a wide-band tunable
modulation stage adapted for providing signals over the plurality
of frequency bands a first filter, comprising frequency selective
elements selective for each of the plurality of frequency bands to
receive a transmission signal from the wide-band tunable modulation
stage and to provide a filtered signal, and a final power amplifier
stage adapted to receive the filtered signal, wherein the signal is
directed from the wide-band tunable modulation stage through the
first filter to the final power amplifier stage.
2. The device of claim 1 wherein the final power amplifier stage
provides output to a second filter, wherein the second filter is
tunable.
3. The device of claim 1 wherein the first filter comprises a
switch.
4. The device of claim 1 wherein a pre-power amplifier is
positioned in the signal path between the modulation stage and the
first filter.
5. The device of claim 1 wherein the final power amplifier stage
comprises but one power amplifier.
6. The device of claim 1 where the frequency selective elements are
selective for at least one of the frequencies 850, 900, 1800, 1900
and 2100 MHz.
7. The device of claim 1 where signals from frequency selective
elements are grouped and directed to power amplifiers in the power
amplifier stage, whereby each power amplifier receives signals from
at least two of the frequency selective elements.
8. A transmitter and receiver arrangement for communication
applications, comprising a transmitter and a receiver adapted to
operate in a plurality of frequency bands, comprising a device
according to claim 1.
9. The transmitter and receiver arrangement of claim 8 wherein the
signal from the final power amplifier stage is directed to at least
one circulator.
10. The transmitter and receiver arrangement of claim 8 or 9
wherein the signal from the final power amplifier stage is directed
to multiple circulators, each adapted to a group of one or more of
the frequencies selected by the frequency selective elements.
11. The transmitter and receiver arrangement of claim 10, wherein a
transmit path is adapted to be connected to a first antenna for
transmission and wherein a receive path is adapted to be connected
to a second antenna for reception.
12. The transmitter and receiver arrangement of claim 10 wherein
multiple low-Q filters are disposed in a transmit path following
the power amplifier stage, each adapted to operate on one or more
of the frequency bands used for duplex operation.
13. The transmitter and receiver arrangement of claim 10 wherein a
filter with directional attenuation characteristics is disposed
between transmitter and receiver.
14. The transmitter and receiver arrangement of claim 10 in which
attenuation between transmitter and receiver is achieved by using
multiple narrow-band circulators with directional attenuation
characteristics, each adapted to operate on one or more of the
frequency bands used for duplex operation.
15. A method of transmitting a signal in a plurality of frequency
bands wherein the signal is directed from a wide-band tunable
modulation stage adapted for providing signals over the plurality
of frequency bands, to a first filter, comprising frequency
selective elements selective for each of the plurality of frequency
bands to receive a transmission signal from the modulation stage
and to provide a filtered signal, and then to a final power
amplifier stage adapted to receive the filtered signal.
Description
BACKGROUND
[0001] The present disclosure relates to a device for transmission
and reception for voice or data communication applications. The
device is capable of duplex operation and adapted to operate in an
environment using a plurality of frequency bands. The present
disclosure also relates to a communication means including a
transmitter and receiver arrangement and antennas.
[0002] Certain mobile telephone applications such as UMTS require
an arrangement having a transmitter and a receiver able to operate
in full duplex mode, i.e. that transmitter and receiver are
simultaneously active. The transmitter and the receiver use a
plurality of frequency bands, each frequency band dedicated to
voice and/or data transmission in one direction. In the arrangement
of interest, transmission and reception may occur over multiple
frequency bands, and the mobile system may be capable of operating
both in half-duplex and in full-duplex modes.
[0003] Receiver sensitivity, for example signal-to-noise ratio, in
a full-duplex operation is degraded by a transmit "noise" signal,
i.e. unwanted signal, in the receive frequency band. A requirement
in such arrangements, therefore, is to reduce transmit noise at the
receiver, preferrably by attenuation to below the level of thermal
noise inherent in any electronic circuitry.
[0004] A frequency band is a small portion of radio communication
frequency spectrum, in which channels are aside for different
telephony systems, such as GSM or UMTS. Each of these bands has a
basic scheme set by ETSI which dictates how it is to be used and
shared, to avoid interference and to set the protocol for
compatibility of transmitters and receivers.
[0005] The power amplifier is the final amplification circuit
portion adapted to drive the transmission signals destined for the
antenna. A power amplifier expends silicon area, and causes power
consumption. Power amplifiers may be either separate circuits, or
integrated into a common substrate along with other transmitter
circuitry.
[0006] Selected attenuation at the receiver is achieved by using a
directional filter such as a circulator with a frequency filtering
characteristic. In some cases, no low-Q filter on the output of the
power amplifier is needed. A diplex filter connects the output to
the antenna. Filters and power amplifiers take a lot of chip space
and require many process steps in manufacturing. It is therefore
desirable to reduce the number of filters, and the number of power
amplifiers, while maintaining the capability of full duplex
operation over multiple frequency bands.
[0007] In various aspects, the invention is defined in the
independent claims. The dependent claims define various embodiments
of the invention.
[0008] In one aspect of the invention, the transmitter and receiver
arrangement is adapted for connection to one or more antennas, and
is capable of full-duplex communication. In the transmitter and
receiver arrangement the number of power amplifiers is fewer than
the number of frequency bands. In an embodiment of the invention,
the device is adapted for operation in a plurality of frequency
bands, and comprises a wide-band tunable modulation stage adapted
for providing signals over the plurality of frequency bands, a
first filter, comprising frequency selective elements selective for
each of the plurality of frequency bands to receive a transmission
signal from the wide-band tunable modulation stage and to provide a
filtered signal, and a final power amplifier stage adapted to
receive the filtered signal, wherein the signal is directed from
the wide-band tunable modulation stage through the first filter to
the final power amplifier stage.
[0009] In an embodiment of the transmitter and receiver arrangement
according to the invention the arrangement is such that there is no
high-Q filter element in a transmit path between the power
amplifiers and the antenna used for transmission. In an embodiment
there is no filter element between the power amplifier and an
antenna connection in the arrangement.
[0010] "High-Q" in this context refers to filters with a high Q
factor, i.e. a high quality factor, as a dimensionless parameter
that gives a measure of the `quality` desired in a particular tuned
circuit. An example of a high-Q filter is a Surface Acoustic Wave
or SAW filter, based on a piezoelectric crystal. Other examples of
high-Q filters include Bulk Acoustic Wave (BAW) filters, ceramic
filters, and composite "meta-filters". A high Q, for the purposes
of the description of the present invention, is understood to be
typically a value well over 20.
[0011] In an embodiment the final power amplification stage has
significantly less than 30 dB gain. This has the effect of reducing
the need for filtering the signal at the output of the power
amplifier. For example, the final power amplifier stage's gain is
less than 25 dB, or even less than 20 dB, or even less than 15
dB.
[0012] An embodiment comprises a power amplifier with a gain of,
for example, in the range of 10 dB. This contributes to achieving
an arrangement wherein there is no high-Q filter at the output of
the power amplifier. It may also permit the arrangement to do
without duplex filters after the power amplification stage, which
in turn has advantages of simple design, improved power efficiency,
and thereby reduced cost.
[0013] In another embodiment the filter configuration comprises
high-Q frequency filters preceeding the final power amplification
stage. This has the advantage of reducing the requirements for
filtering after the power amplification stage.
[0014] In another embodiment, a filter with directional attenuation
characteristics is disposed between the transmitter and the
receiver. This allows signals from the transmitter, destined for
the antenna, to be separated from signals received from the antenna
and destined for the receiver. In one embodiment, the filter with
directional attenuation characteristics is disposed on a signal
path for coupling the antenna to the transmitter and to the
receiver.
[0015] Yet another embodiment features attenuation between
transmitter and receiver which is achieved by using multiple
narrow-band filters with directional attenuation characteristics,
each adapted to operate on one or more of the frequency bands used
for duplex operation.
[0016] According to another aspect of the invention, there is
provided a method for duplex signal transmission and reception in
mobile communication. The method includes:
[0017] operating a transmitter and receiver arrangement in a
plurality of frequency bands,
[0018] amplifying the signal using power amplifiers in a final
power amplifier stage of the transmitter and receiver arrangement,
wherein the number power amplifiers in the final power amplifier
stage is fewer than the number of frequency bands in the plurality
of frequency bands, and
[0019] filtering an amplified signal using a filter configuration
without high-Q frequency filters following the final power
amplification stage.
[0020] By using power amplifiers in a final power amplifier stage
of the transmitter and receiver arrangement, wherein the number
power amplifiers in the final power amplifier stage is fewer than
the number of frequency bands in the plurality of frequency bands,
the method achieves performance sufficient for UMTS operation at
lower power consumption. In particular, coupling of the amplified
signal on the transmit signal path into a receive path is
acceptably low.
[0021] By using a filter configuration without high-Q filters
following the final power amplification stage, the method achieves
a simpler routing of the signal path between transmitter and
antenna, and lower power consumption.
[0022] In an embodiment, the method uses a circulator to achieve
selective attenuation. The circulator directs a maxium of signal
from the transmitter to the connection to an antenna and from the
connection to the antenna to the receiver, while allowing little
signal to pass from the transmitter to the receiver.
[0023] In an embodiment, the method uses multiple circulators, each
adapted to a group of one or more of the frequency bands used for
duplex operation. Thus, signals can be separated into groups which
further reduces the incidence of signals on the transmit path from
the transmitter which pass to the receiver.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0024] The figures show selected exemplary embodiments of the
invention. In particular,
[0025] FIG. 1 shows a first embodiment with two circulators each at
a connection point on a signal path coupling transmitter, receiver,
and an antenna connected to the arrangement;
[0026] FIG. 2 shows a second embodiment with a single circulator at
a connection point on a signal path coupling transmitter, receiver,
and an antenna connected to the arrangement;
[0027] FIG. 3 shows a third embodiment with high-Q filters in a
signal path to the antenna before the power amplifiers;
[0028] FIG. 4 shows a fourth embodiment with a single power
amplifier and high-Q filters in a signal path to the antenna before
the power amplifier; and
[0029] FIG. 5 shows a fifth embodiment with separate transmit and
receive antennas.
DETAILED DESCRIPTION
[0030] The following detailed description explains exemplary
embodiments of the present invention. The description is not to be
taken in a limiting sense, but is made only for the purpose of
illustrating the general principles of embodiments of the invention
while the scope of protection is only determined by the appended
claims.
[0031] In the exemplary embodiments shown in the drawings and
described below, any direct connection or coupling between
functional blocks, devices, components or other physical or
functional units shown in the drawings or described herein can
generally also be implemented by an indirect connection or
coupling. Functional blocks may be implemented in hardware,
firmware, software, or a combination thereof.
[0032] Further, it is to be understood that the features of the
various exemplary embodiments described herein may be combined with
each other, unless specifically noted otherwise.
[0033] In the various figures, identical or similar entities,
modules, devices etc. may have assigned the same reference
number.
[0034] A preferred first embodiment of the invention is shown in
FIG. 1. Embodiments of the invention, such as the first embodiment,
could be implemented, for example, in a mobile phone. The first
embodiment comprises an arrangement of a transmit circuitry portion
101 and a receive circuitry portion 102. Further the embodiment has
a passive portion 103 connected to an antenna 136. The transmit
circuitry portion 101 is coupled to the passive portion 103. The
passive portion 103, via an antenna feed line 135, connects to the
antenna 136 and is also coupled to the receive circuitry portion
102.
[0035] Transmit circuitry portion 101 comprises a transmitter 110,
a transmit filter element bank 113, and a pair of power amplifiers
118a, 118b. The power amplifiers 118a, 118b are identified as the
last active amplification circuitry on the transmit signal path to
the antenna.
[0036] Transmitter 110 is of a conventional type and comprises
wide-band tunable modulation stages 107a, 107b and low power
preamplifiers 108a, 108b, 108c, 108d, 108e each adapted to operate
in a different frequency band, i.e., at 850, 900, 1800, 1900 and
2100 MHz, respectively. Differential output line pairs 109a, 109b,
109c, 109d, 109e, each associated to a respective one of the
afore-mentioned frequency bands, connect transmitter 110 to
transmit selective band filter element bank 113.
[0037] Transmit filter element bank 113 comprises a low-band group
of filter elements including a first filter element 114a and a
second filter element 114b adapted to operate in the frequency band
of 850 MHz and 900 MHz, respectively. Transmit filter element bank
113 comprises a high-band group of filter elements including a
third filter element 115a, a fourth filter element 115b, and fifth
filter element 115c adapted to operate in the frequency band of
1800 MHz, 1900 MHz and 2100 MHz, respectively. Each filter element
114a, 114b; 115a, 115b, 115c receives a different one of the
differential output line pairs 109a, 109b, 109c, 109d, 109e,
respectively. Outputs of filter elements 114a and 114b of the
low-band group of filter elements are connected to one another to
form a low-band common filter element output 117a. Outputs of
filter elements 115a, 115b and 115c of the high-band group of
filter elements are connected to one another to form a high-band
common filter element output 117b. Thus, low-band common filter
element output 117a and high-band common filter element output 117b
form a pair of filter bank outputs.
[0038] The pair of power amplifiers comprises low-band power
amplifier 118a and high-band power amplifier 118b. An input of
low-band power amplifier 118a is connected, via a connection from
filter bank output 117a, to transmit filter element bank 113. An
output of low-band power amplifier 118a is connected to the passive
portion 103. An input of high-band power amplifier 118b is
connected, via a connection from transmit filter element bank
output 117b, to transmit filter element bank 113. An output of
high-band power amplifier 118b is connected to the passive portion
103.
[0039] Receive circuitry portion 102 comprises a receive filter
element bank 123 and a receiver 120 of a conventional type. Receive
filter element bank 123 comprises a low-band group of filter
elements including a first filter element 124a and a second filter
element 124b adapted to suppress signals outside and to operate in
the frequency band of 850 MHz and 900 MHz, respectively. Receive
filter element bank 123 comprises a high-band group of filter
elements including a third filter element 125a, a fourth filter
element 125b, and fifth filter element 125c adapted to suppress
signals outside and to operate in the frequency band of 1800 MHz,
1900 MHz and 2100 MHz, respectively. Each filter element 124a,
124b; 125a, 125b, 125c receives a different one of five input lines
as a connection from the passive portion 103. Differential output
line pairs 129a, 129b, 129c, 129d, 129e connect the filter elements
124a, 124b; 125a, 125b, 125c of receive filter element bank 123 to
receiver 120. Receiver 120 comprises low power active circuitry
portions (not shown) each adapted to operate in a different
frequency band, i.e., at 850, 900, 1800, 1900 and 2100 MHz,
respectively, and each being coupled to a corresponding
differential output line pair 129a, 129b, 129c, 129d, 129e.
[0040] Passive portion 103 comprises a low-band circulator 131a, a
high-band circulator 131b, a low-band band switch 126a and a
high-band band switch 126b, a diplex filter 132, and an antenna
connection 133. A circulator is a directional filter. A typical
circulator offers up to 20 dB attenuation in the "backwards"
direction but only a few dB in the "forward" direction.
[0041] Low-band circulator 131a and high-band circulator 131b have
each three terminals wherein the terminals can be accessed in such
a way that when a signal is fed into any terminal it is transferred
to the next terminal only, the first terminal being counted as
following the last in numeric order. A first terminal of low-band
circulator 131a is coupled to the output of low-band power
amplifier 118a. A second terminal of low-band circulator 131a is
coupled to a first terminal 141 of diplex filter 132. A third
terminal of low-band circulator 131a is coupled to an input of
low-band band switch 126a. A first terminal of high-band circulator
131b is coupled to the output of high-band power amplifier 118b. A
second terminal of high-band circulator 131b is coupled to a second
terminal 142 of diplex filter 132. A third terminal of high-band
circulator 131b is coupled to an input of high-band band switch
126b.
[0042] Low-band band switch 126a comprises a single pole switch
adapted to select between two connections from the third terminal
of low-band circulator 131a either to first low-band filter element
124a or to second low-band filter element 124b. High-band band
switch 126b comprises a single pole switch adapted to select
between three connections from the third terminal of high-band
circulator 131b either to first high-band filter element 125a or to
second high-band filter element 125b or to third high-band filter
element 125c.
[0043] Diplex filter 132 is connected, via a third terminal 143, to
antenna connection 133. The diplex filter 132 has a signal path
that comprises a low-pass filter and a high-pass filter. The
low-pass filter and the high-pass filter both do not have a high
quality factor; the combination presents an insertion loss
sufficiently small to allow a transmit signal passing through the
filter to transmitted while suppressing effectively cross coupling
of signals from the low-frequency band to the high-frequency band
and vice versa.
[0044] In operation of the first embodiment, a baseband signal
representing, for example, user speech information or data to be
transferred, is provided to the transmit circuitry portion 101 for
transmission. In particular, the baseband signal is input to
transmitter 110 where the baseband signal modulates a radio
frequency signal generated in one of the low power wide-band
tunable modulation stages 107a, 107b circuitry portions, the
portion being selected such that the frequency of the radio
frequency signal is inside a frequency band designated by user's
mobile phone operator for communication.
[0045] The radio frequency signal henceforth defines a transmit
signal path extending through the transmit circuitry portion 101
and the passive portion 103 to antenna 136. In particular, the
radio frequency signal is outputted from one of the low power
preamplifiers 108a, 108b, 108c, 108d, 108e of transmitter 110, via
a corresponding one of the differential output line pairs 109a,
109b, 109c, 109d, 109e. The signal travels to filter element bank
113 where it is coupled to the respective filter element 114a,
114b; 115a, 115b, 115c associated with the selected frequency's
designated frequency band. The respective filter element suppresses
signal components outside the designated frequency band. Thereby,
the radio frequency signal is cleared of undesired components.
[0046] Depending on whether the radio frequency signal passes
through one of the low-band group filter elements 114a and 114b or
through one of the high-band group of filter elements 115a, 115b,
115c, the filtered radio frequency signal leaves filter element
bank 113 either via low-band common filter element output 117a or
via high-band common filter element output 117b and is coupled to
the input of low-band power amplifier 118a or to the input of
high-band power amplifier 118b, respectively. Depending on whether
the filtered radio frequency signal is a low-band or a high-band
signal, either the low-band power amplifier 118a or the high-band
power amplifier 118b provides, at its output, the radio frequency
signal sufficiently amplified for passing the circulator 131a or
131b, respectively, and the diplex filter 132 to then be
transmitted by antenna 136. Thus, the amplification in the
respective power amplifier 118a, 118b may be less than in a case
where a filter having a high Q factor is positioned in place of the
diplex filter 132. In a variant of the present embodiment, the
low-band amplifier and the high-band amplifier could simultaneously
amplify a low-band signal and a high-band signal, respectively, to
enable simultaneous transmission of both the low-band signal and
the high-band signal.
[0047] The amplified radio frequency signal travels from the power
amplifiers' respective output to the passive portion 103. In the
passive portion 103, the amplified radio frequency signal, if
within the low band, enters low-band circulator 131a via the first
terminal and leaves low-band circulator 131a via the second
terminal. If the radio frequency signal is within the high band,
the radio frequency signal enters high-band circulator 131b via the
second terminal and leaves high-band circulator 131b via the third
terminal. In comparison with the radio frequency signal output via
the third terminal of circulator 131a, 131b, a much attenuated
radio frequency signal may occur at the first terminal of
circulator 131a, 131b as well. In the given example, the
attenuation is more than 10 dB and up to about 20 dB and is not
necessarily the same in low-band circulator 131a and in high-band
circulator 131b.
[0048] The low-band radio frequency signal travels from the second
terminal of low-band circulator 131a to the first terminal of the
diplex filter 132. The high-band radio frequency signal travels
from the second terminal of the high-band circulator 131b to the
second terminal of the diplex filter 132. The radio frequency
signal passes through diplex filter 132 and is output from diplex
filter 132 at the third terminal 143. The radio frequency signal
then travels via antenna connection 133 to antenna 136 that
radiates the radio frequency signal. A signal received at the
antenna 136, in operation, defines a receive signal path that
extends from the antenna 136 through the passive portion 103 and
into the receive circuitry portion 102. The signal from antenna 136
first passes through the antenna connection 133 and then to the
third terminal 143 of the diplex filter 132. The diplex filter 132
passes a low-band portion of the signal through to the first
terminal of the diplex filter. From there, the low-band portion of
the signal, i.e., a low-band signal, is coupled to the second
terminal of the low-band circulator 131a. A high-band portion of
the signal passes through the diplex filter 132 to the second
terminal of the diplex filter 132. From there, the high-band
portion of the signal, i.e., a high-band signal, is coupled to the
high-band circulator 131b.
[0049] The low-band signal leaves low-band circulator 131a via the
third terminal and continues to the low-band switch 126a. Depending
on user settings, low-band switch 126a in turn directs the signal
to filter element 124a for an 850 MHz signal or to filter element
124b for a 900 MHz signal.
[0050] The high-band signal leaves high-band circulator 131b via
the third terminal and continues to high-band switch 126b.
Depending on user settings, high-band switch 126b in turn directs
the signal to the filter element 125a for an 1800 MHz signal, 125b
for a 1900 MHz signal or filter element 125c for a 2100 MHz
signal.
[0051] From the respective filter elements of filter element bank
123 the signal passes over the corresponding differential input
line pairs 129a, 129b, 129c, 129d, 129e to the receiver 120. If
receiver 120 is a conventional type receiver, the receiver 120, for
example, will demodulate the signal and down-convert the signal to
obtain a baseband signal for further processing.
[0052] As shown in the first embodiment (FIG. 1) circulators 131a,
131b with a frequency-specific behavior make it possible to have at
least one of the power amplifiers amplifying signals from more than
one frequency band. In other words, implementation of circulators
131a, 131b enables consolidation of power amplifiers such that the
device comprises fewer power amplifiers in the transmit signal path
than there are frequency bands that the device is adapted to
operate with. For example, the first embodiment is adapted to
operate both in a group of high-band frequencies and a group of
low-band frequencies. For each group there is a specific power
amplifier of moderate gain, for example 10 dB. The gain is moderate
in comparison with a gain of a power amplifier of a conventional
arrangement that, for example, includes a power amplifier with a
gain of 30 dB. The moderate gain of the power amplifiers 118a, 118b
of the present embodiment of the invention is possible because of
the low loss in the transmit signal path, in particular down stream
of the power amplifiers 118a, 118b. Low loss is achieved by using
circulators 131a, 131b. The high-band circulator 131b and the
low-band circulator 131a are used, such that no switch is needed
between the power amplifiers 118a, 118b and the antenna 136. The
circulators 131a, 131b, which are filters with directional
attenuation characteristics, allow signals from the transmitter
110, destined for the antenna 136, to be separated from signals
received from the antenna 136 and destined for the receiver 120. In
this embodiment, the arrangement uses multiple circulators, each
adapted to a group of one or more of the frequency bands used for
duplex operation. Thus, signals can be separated into groups which
further reduces the incidence of signals on the transmit path from
the transmitter which pass to the receiver.
[0053] The low or moderate gain of the power amplifiers 118a, 118b
means that there is no high-Q filter required after these
amplifiers, although one could be used. Grouping of the
frequencies, i.e., amplifying of signals irrespective of the
frequency band within one group by the same power amplifier, yields
fewer power amplifiers than the number of frequency bands in the
plurality of frequency bands, in this case two amplifiers to be
used with five frequency bands. The effect of these measures is to
reduce the complexity of the complete arrangement.
[0054] Operation over multiple frequency bands, in a variant of the
exemplary embodiment, requires that attenuation is achieved between
a transmitted signal and a received signal, as seen by the
receiver, in order that the received signal is not obscured by the
transmitted signal. This becomes less challenging as the separation
between the transmit and receive frequency bands increases.
Separate bands means that there is a frequency band between those
used for transmission and/or reception that is used for neither
transmission nor reception in the instant arrangement. The
frequency bands might for example be those defined by 3GPP, the 3rd
Generation Partnership Project. Attenuation can be achieved in part
by a filtering of the transmitted signal after preamplification but
prior to the power amplification, or by establishing an attenuation
between the paths transmitter-to-antenna and antenna-to-receiver.
Duplex filters can achieve as much as 50 dB attenuation in the
relevant frequencies, but at high cost due to more challenging
manufacturing requirements and due to a 2-3 dB insertion loss.
[0055] Placement of high-Q filters before the final Power Amplifier
rather than after it leads to lower costs. This can be done if the
final Power Amplifier stage has less gain than the overall transmit
gain. For example, if the gain from modulator to antenna should be
of the order of 30 dB, then the final Power Amplifier might ideally
have a gain of 10 dB. In addition, the reduced gain may allow power
savings. The gain of the final Power Amplifier stage might be less
than 30 dB, or 25 dB or less, or 20 dB or less, or 15 dB or less,
or 12 dB or less, or 10 dB or less, or 9 dB or less, or 8 dB or
less. The final Power Amplifier stage will also have a gain greater
than or equal to 3 dB.
[0056] Power consumption is also reduced, by reducing the number of
power amplifiers used by the transmitter to transmit over all
relevant frequency bands.
[0057] A second embodiment is presented in FIG. 2. Like the first
embodiment, the second embodiment encompasses a transmit circuitry
portion 201, a receive circuitry portion 202 and a passive portion
203.
[0058] The transmit circuitry portion 201 includes a transmitter
210 adapted to provide a signal in a predetermined and/or selected
frequency band comprising wide-band tunable modulation stages 207a,
207b, a pre-power amplifier 211, a switch 212, a transmit selective
band filter bank 213, a power amplifier 218 and a tunable filter
219. A transmit signal path to the antenna for all frequencies
starts from the transmitter 210 to the pre-power amplifier 211,
then through switch 212, transmit bandpass filter bank 213, and the
power amplifier 218. The pre-power amplifier 211 is identified as
such because, on the transmit signal path, it comes before the
power amplifier 218. The switch 212 is adapted to direct the
transmit signal path to an element of the frequency band filter
bank 213. The transmit signal path then leads from the band-pass
filter bank 213 to the switch 216, which is adapted to direct the
signal in the selected frequency band to the power amplifier 218.
From the power amplifier 218, the transmit signal path leads to the
tunable filter 219.
[0059] The passive portion 203 includes a circulator 231, an
antenna connection 233 and an antenna 236. The passive portion 203
takes the transmit signal path from the tunable filter 219 in the
transmit circuit portion 210 to a first terminal of the circulator
231. The signal path then leads from a second terminal of the
circulator 231 along the antenna connection 233 to the antenna 236.
The passive portion 203 further defines a portion of a receive
signal path of the second embodiment that starts at the antenna
236, and leads to the second terminal of the circulator 231.
[0060] The receive circuitry portion 202 includes a switch 226, a
filter bank 223 including filter elements each adapted to pass a
signal in a different selected frequency band and to essentially
suppress signals outside the selected frequency band, and a
receiver 220. The switch 226 is adapted to direct the receive
signal path to the frequency band filter element of interest in the
receive bandpass filter bank 223. The signal path then continues
from the filter element to the receiver 220.
[0061] The second embodiment shares many features with the first
embodiment. However, the following is different in the second
embodiment: as shown in FIG. 2, only one circulator is used, and a
switch 216 is used. The switch 216 is placed upstream of the power
amplifier 218. Alternatively the switch 216 could be placed between
power amplifier 218 and antenna 236. In the exemplary embodiment
the system comprises a transmit preamplifier 211. In the present
example, the transmit preamplifier 211 is common to all
frequencies. Downstream of the common transmit preamplifier 211 is
arranged a switch 212 to direct the transmit signal to a filter
213, wherein the filter 213 is particularly adapted to pass
respective frequency bands. Further downstream is arranged the
switch 216 to connect the frequency filter 213 to the power
amplifier 218.
[0062] As in the first embodiment, the power amplifier 218 of the
second embodiment has a moderate gain, for example 10 dB. The
moderate gain contributes to achieving an arrangement wherein there
is no high-Q filter at the output of the power amplifier 218. A
low-Q tunable filter 219 is arranged down-stream in the transmit
path to the circulator 231 and antenna 236. This embodiment also
permits the arrangement to function without duplex filters
downstream of the power amplification stage, which in turn has
advantages of simple design, improved power efficiency, and thereby
reduced cost.
[0063] The moderate gain or even a low gain of the power amplifier
218, is made possible by the contribution of the transmit
preamplifier 211. The moderate gain means that there is no high-Q
filter downstream of the power amplifier 218. Selective switching
of the frequency band means that there is only one power amplifier
218, which is fewer than the number of frequency bands in the
plurality of frequency bands. The effect of these measures is to
reduce the complexity of the complete arrangement.
[0064] Like the first and second embodiments, the third embodiment
(FIG. 3) encompasses a transmit circuitry portion 301, a receive
circuitry portion 302 and a passive portion 303. In the third
embodiment, the transmit circuitry portion 301 and the receive
circuitry portion 302, for example, are essentially the same as the
corresponding transmit circuitry portion 101 and as the
corresponding receive circuitry portion 102, respectively, of the
first embodiment.
[0065] The transmit circuitry portion 301 includes a transmitter
310 adapted to provide a signal in a predetermined and/or selected
frequency band, a transmit bandpass filter bank 313, and power
amplifiers 318a and 318b.
[0066] The passive portion 303 comprises tunable filters 319a and
319b, a diplex filter 332 and a port 341 to an antenna 336.
Further, the passive portion 303 comprises receive tunable filters
329a and 329b, and switches 326a and 326b. The switches 326a and
326b are adapted to direct the receive signal path to the frequency
band filter element of interest in the receive bandpass filter bank
323.
[0067] The receive portion 302 comprises a selective band filter
bank 323 including selective band filter elements 324a, 324b, 325a,
325b, 325c each adapted to pass a signal in a different selected
frequency band and to essentially suppress signals outside the
selected frequency band, and a receiver 320.
[0068] A transmit signal path for all frequencies starts from the
wide-band tunable modulation stages 207a, 207b and preamplifier 208
of transmitter 310 through the pre-power amplifier 211 to a
frequency band filter element in the transmit bandpass filter bank
313. The transmit signal path for 850 MHz and 900 MHz frequencies
then continues to the low-band power amplifier 318a, while the
transmit path for the 1800 MHz, 1900 MHz and 2100 MHz frequencies
continues to the high-band power amplifier 318b. The transmit
signal path from the low-band power amplifier continues to the
transmit tunable filter 319a while the transmit signal path from
the high-band power amplifier 318b continues to the transmit
tunable filter 319b.
[0069] The transmit signal path from the low-band power amplifier
318a continues to the transmit tunable filter 319a and further
downstream to both the diplex filter 332 and the receive tunable
filter 329a. The transmit signal path from the high-band power
amplifier 318b continues to the transmit tunable filter 319b and
further downstream to both the diplex filter 332 and the receive
tunable filter 329b. From the diplex filter both the low-band and
the high-band transmit signal paths continue via port 341 to the
antenna 336.
[0070] The receive signal path for all frequencies starts at the
antenna 336 and continues via port 341 to the diplex filter 332.
From the diplex filter 332, a low-band frequency path continues to
the receive tunable filter 329a and then on to the switch 326a. The
switch 326a is adapted to direct a signal on the receive signal
path to one of two connections 324a and 324b leading to the receive
bandpass filter bank 323, i.e. to filters for 850 MHz frequencies
and for 900 MHz frequencies, respectively. Downstream of the filter
bank 323, the signal path proceeds to the receiver 320. A high-band
frequency path from the diplex filter 332 continues to the receive
tunable filter 329b and then on to the switch 326b. The switch 326b
is adapted to direct a signal on the receive signal path to one of
three connections 324c, 324d, 324e leading to the receive bandpass
filter bank 323, i.e., to filters for 1800 MHz, 1900 MHz and 2100
MHz frequencies, respectively.
[0071] The arrangement of the third embodiment (FIG. 3) uses groups
of frequency bands and a diplex filter 332 for attenuation, to
achieve lower complexity and hence lower cost. No switch is used in
the path from power amplifiers to antenna 336, given the grouping
of frequencies, in this case high band group and low band group;
instead, a simple diplex filter provides attenuation between the
low group and the high group of frequencies. The high band
corresponds to 1.8 to 2.1 GHz, while the low band is of the range
850-900 kHz. The transmitter 310 comprises two wide-band tunable
modulation stages 307a, 307b, and pre-amplifiers 308a, 308b, 308c,
308d, 308e.
[0072] This allows a simplification of the filtering requirements,
since only groups of frequencies need be considered by the tunable
filters on the transmit 319a, 319b and receive 329a, 329b paths.
The arrangement includes a diplex filter 332 to separate between
the "high" group of frequencies and the "low" group of frequencies.
However, the arrangement does not necessarily use any duplex
filter. Yet, the arrangement maintains a separation between signals
from the transmitter, destined for the antenna, and signals
received from the antenna and destined for the receiver. Thus this
arrangement requires no high-Q filter downstream of the power
amplifier, and the diplex filter is sufficient to combine the
outputs of the two power amplifiers 318a and 318b, which are fewer
than the number of frequency bands in the plurality of frequency
bands (850 MHz, 900 MHz, 1800 MHz, 1900 MHz and 2100 MHz).
[0073] The fourth embodiment (FIG. 4) comprises an arrangement with
a power pre-amplifier. Like the embodiments discussed above, the
fourth embodiment encompasses a transmit circuitry portion 401, a
receive circuitry portion 402 and a passive portion 403.
[0074] The transmit circuitry portion 401 comprises a transmitter
410 with wide-band tunable modulation stages 407a, 407b and
wideband pre-amplifier 408, power pre-amplifier 411, a switch 412,
a transmit bandpass filter bank 413, a second switch 416, a power
amplifier 418 and a tunable filter 419. The receive circuitry
portion 402 comprises a receive tunable filter 429, a receive
switch 426, a receive filter bank 423 and a receiver 420. The
passive portion 403 comprises a port 433 to an antenna 436.
[0075] The transmit signal path is from the wide-band tunable
modulation stages 407a, 407b of transmitter 410 to preamplifier 408
and then to pre-amplifier 411 followed by switch 412 which is
adapted to direct the transmit signal to a filter element 414 in
the transmit selective band filter bank 413. Downstream of the
selective band filter bank 413, the signal path passes through a
second switch 416, which is adapted to select an output signal of
the filter element 414 and direct that output signal to the power
amplifier 418. From the power amplifier 418 the signal path passes
through tunable filter 419 and continues on to both antenna 436 and
receive tunable filter 429. The receive signal path starts at the
antenna 436, and continues to the receive tunable filter 429 and on
to the receive switch 426. The receive switch 426 is adapted to
direct the signal to a filter element 424 in the receive filter
bank 423. From the receive filter bank 423, the signal path
continues to the receiver 420.
[0076] In the arrangement of the fourth embodiment (FIG. 4) use of
the power pre-amplifier 411 allows the use of switches 412 and 416
in the transmit path without having any switch being located
between the power amplifier 418 and the antenna 436. In particular,
because of a signal's pre-amplification, the power amplifier 418
needs less gain and, consequently, does not introduce so much noise
as to require additional filtering of an amplified signal. Low-Q
filters 419, 429 are used in both the transmit and the receive
paths to provide suitable attenuation of the transmitted signal at
the receiver. Band selection is done in the filter elements 414a,
414b, 415a, 415b, 415c between the power pre-amplifier 411 and the
power amplifier 418. In this implementation, a single power
preamplifier 411 and a single power amplifier 418 are used. In a
variant of the fourth embodiment, more than a single power
pre-amplifier and/or more than a single power amplifier could be
used. The multiple power pre-amplifiers and/or the multiple power
amplifiers could be arranged sequentially in the signal path and/or
in parallel wherein the multiple amplifiers would be adapted to
amplify a signal within a predetermined frequency band. Due to the
reduced amplification of each stage, the linearity requirements are
reduced, which in a variant of the fourth embodiment, leads to
reduced power consumption.
[0077] The fourth embodiment uses no duplex filters in the signal
path downstream of the power amplification stage. The absence of
duplex filters in turn makes it possible to direct signals of any
frequency band to the common power amplifier or set of power
amplifiers, which has advantages of simple design, improved power
efficiency, and thereby reduced cost. The design also benefits from
having the power amplifier or amplifiers after the frequency band
selection switches, which reduces the requirements on the switches
for current-carrying capacity.
[0078] In the fourth embodiment the final power amplification stage
has significantly less than 30 dB gain. The power amplifier 418 has
a gain of, for example in the range of 10 dB. When compared to a
power amplifier in a conventional design of similar functionality,
the gain of power amplifier 418 is comparatively low. The low gain
of the power amplifier 418 is made possible by the contribution of
the transmit power preamplifier 411, means that there is no high-Q
filter needed in the transmit signal path downstream of the power
amplifier 418. Selective switching of the frequency band means that
there are less power amplifiers than there are frequency bands, for
example, in the fourth embodiment there is one power amplifier 418,
which is fewer than the number of frequency bands in the plurality
of frequency bands. The effect of these measures is to reduce the
complexity of the complete arrangement.
[0079] The fifth embodiment is presented in FIG. 5. Like the
previously disclosed embodiments, the fifth embodiment encompasses
a transmit circuitry portion 501 and a receive circuitry portion
502, but unlike the previously disclosed embodiments that encompass
a single passive portion, the fifth embodiment encompasses two
passive portions, namely a transmit passive portion 504 and a
receive passive portion 503.
[0080] The transmit circuitry 501 comprises a transmitter 510 with
wide-band tunable modulation stages 507a, 507b and preamplifier
508, a pre-power amplifier 511 and a switch 512. It also comprises
selective band filter element 514a, 514b, 515a, 515b, 515c of a
transmit selective band filter bank 513, a switch 516, a power
amplifier and a tunable filter 519. The transmit passive portion
504 comprises a transmit antenna connection 534 adapted to connect
to a transmit antenna 537.
[0081] The transmit signal path starts at the transmitter 510 with
wide-band tunable modulation stages 507a, 507b and preamplifier
508, and continues downstream to the pre-power amplifier 511 and
then to a switch 512. The switch 512 is adapted to direct a
transmit signal to one of the filter elements 514a, 514b, 515a,
515b, 515c of the transmit filter bank 513 adapted to pass a
frequency band used by the transmit signal. From the filter element
514 the transmit signal path passes to downstream switch 516 which
is adapted to direct the transmit signal to the power amplifier
518. From the power amplifier 518 the signal path passes downstream
to tunable filter 519 and then via antenna connection 534 to
transmit antenna 537.
[0082] The receive circuitry 502 comprises a switch 526, and a
receive filter bank 523 including filter elements 524a, 524b, 525a,
525b, 525c, as well as a receiver 520. The receive passive
circuitry portion 503 comprises receive antenna connection 533
adapted to connect to receive antenna 536 (distinct from the
transmit antenna 537). In a variant of the fifth embodiment, both
the transmit antenna connection 534 and the receive antenna
connection 533 are adapted to be connected to a single antenna that
may include matching elements in the transmit signal path and/or in
the receive signal path.
[0083] The receive signal path begins at the receive antenna 536
and continues to switch 526. The switch 526 is adapted to direct
the receive signal to one of the filter elements 524a, 524b, 525a,
525b, 525c in the receive filter bank 523. From the filter bank 523
the signal path passes downstream to the receiver 520.
[0084] The arrangement of the fifth embodiment (FIG. 5) presents an
alternate configuration with two separate and distinct signal paths
where, in operation, the transmit signal goes to the transmit
antenna 537 and the receive signal is taken from the receive
antenna 536, as compared to the shared passive portion including a
shared antenna port in the first four embodiments. The attenuation
achieved by using separate antennas or, at least, separate transmit
signal path and receive signal path including the respective
antenna ports or antenna connections 534, 533, can be used to
reduce the quality requirements on the low-Q filters, and in a
variant of the instant embodiment to eliminate the filter present
in the receive path from antenna 536 to receiver 520 of other
embodiments. The total attenuation in this embodiment is 20 dB,
with 10 dB coming from the low-Q filter 519, and 10 dB from the
separation between transmit antenna connection 534 and receive
antenna portion 533.
[0085] The low gain of the power amplifier 518, made possible by
the contribution of the transmit pre-power amplifier 511, means
that there is no high-Q filter downstream of the power amplifier
518. Selective switching of the frequency band means that there is
only one power amplifier 518, which is fewer than the number of
frequency bands in the plurality of frequency bands. The effect of
these measures is to reduce the complexity of the complete
arrangement.
[0086] In the above description, embodiments have been shown and
described enabling those skilled in the art in sufficient detail to
practice the teachings disclosed herein. Other embodiments may be
utilized and derived there from, such that structural and logical
substitutions and changes may be made without departing from the
scope of this disclosure.
[0087] This Detailed Description, therefore, is not to be taken in
a limiting sense, and the scope of various embodiments is defined
only by the appended claims, along with the full range of
equivalents to which such claims are entitled.
[0088] Such embodiments of the inventive subject matter may be
referred to herein, individually and/or collectively, by the term
"invention" merely for convenience and without intending to
voluntarily limit the scope of this application to any single
invention or inventive concept if more than one is in fact
disclosed. Thus, although specific embodiments have been
illustrated and described herein, it should be appreciated that any
arrangement calculated to achieve the same purpose may be
substituted for the specific embodiments shown. This disclosure is
intended to cover any and all adaptations or variations of various
embodiments. Combinations of the above embodiments, and other
embodiments not specifically described herein, will be apparent to
those of skill in the art upon reviewing the above description.
[0089] It is further to be noted that embodiments described in
combination with specific entities may in addition to an
implementation in these entity also include one or more
implementations in one or more sub-entities or sub-divisions of
said described entity. For example, specific embodiments described
herein described herein to be implemented in a transmitter,
receiver or transceiver may be implemented in sub-entities such as
a chip or a circuit provided in such an entity.
[0090] The accompanying drawings that form a part hereof show by
way of illustration, and not of limitation, specific embodiments in
which the subject matter may be practiced.
[0091] In the foregoing Detailed Description, in some instances
various features are described grouped together in a single
embodiment. This is not to be interpreted such that the claimed
embodiments require more features than are expressly recited in
each claim. Rather, as the following claims reflect, inventive
subject matter can lie in less than all features of a single
disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, where each claim may
stand on its own as a separate embodiment. While each claim may
stand on its own as a separate embodiment, it is to be noted
that--although a dependent claim may refer in the claims to a
specific combination with one or more other claims--other
embodiments may also include a combination of the dependent claim
with the subject matter of each other dependent claim.
[0092] It is further to be noted that methods disclosed in the
specification or in the claims may be implemented by a device
having means for performing each of the respective steps of these
methods.
* * * * *