U.S. patent application number 10/807244 was filed with the patent office on 2004-12-02 for power amplifier and radio communication device using the amplifier.
Invention is credited to Araki, Yuta, Kayano, Hiroyuki, Yamaguchi, Keiichi.
Application Number | 20040239420 10/807244 |
Document ID | / |
Family ID | 33447631 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040239420 |
Kind Code |
A1 |
Araki, Yuta ; et
al. |
December 2, 2004 |
Power amplifier and radio communication device using the
amplifier
Abstract
A power amplifier includes amplifier elements to amplify input
signals of different frequencies. The amplifier also includes a
power supply circuit that includes a common power supply path
including an end connected to a power supply input terminal
connected to a DC power supply. The amplifier further includes
individual power supply paths each including an end connected to
the other end of the common power supply path, and the other end
connected to the main electrode of a corresponding one of the
amplifier elements. The individual power supply paths have
different impedances.
Inventors: |
Araki, Yuta; (Tokyo, JP)
; Kayano, Hiroyuki; (Fujisawa-shi, JP) ;
Yamaguchi, Keiichi; (Kawasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
33447631 |
Appl. No.: |
10/807244 |
Filed: |
March 24, 2004 |
Current U.S.
Class: |
330/126 |
Current CPC
Class: |
H05K 1/0265 20130101;
H03F 1/0277 20130101; H05K 1/165 20130101; H03F 2200/294 20130101;
H03F 2200/429 20130101; H03F 3/68 20130101; H03F 2200/372 20130101;
H05K 2201/09254 20130101; H05K 2201/09263 20130101 |
Class at
Publication: |
330/126 |
International
Class: |
H03F 003/68 |
Foreign Application Data
Date |
Code |
Application Number |
May 26, 2003 |
JP |
2003-147917 |
Claims
What is claimed is:
1. A power amplifier comprising: a first amplifier element
configured to amplify a first input signal of a first frequency,
the first amplifier element including a first input terminal which
receives the first input signal, and a first output terminal which
outputs a first output signal obtained by amplifying the first
input signal; a second amplifier element configured to amplify a
second input signal of a second frequency, the second amplifier
element including a second input terminal which receives the second
input signal, and a second output terminal which outputs a signal
obtained by amplifying the second input signal; a power supply
input terminal connected to a direct-current power supply; a common
power supply path including an end connected to the power supply
input terminal, and another end; a first individual power supply
path including an end connected to the another end of the common
power supply path, and another end connected to the first output
terminal, the first individual power supply path having a first
impedance; and a second individual power supply path including an
end connected to the another end of the common power supply path,
and another end connected to the second output terminal, the second
individual power supply path having a second impedance.
2. The power amplifier according to claim 1, further comprising a
multilayer wiring board comprising a first layer provided with the
first amplifier element and the second amplifier element, and a
second layer provided with the common power supply path and the
first individual power supply path and the second individual power
supply path.
3. The power amplifier according to claim 1, further comprising a
multilayer wiring board comprising a first layer and a second
layer, wherein the first amplifier element and the second amplifier
element are provided on the first layer, and the common power
supply path, the first individual power supply path and the second
individual power supply paths are provided on the first layer and
the second layer.
4. The power amplifier according to claim 1, further comprising a
multilayer wiring board comprising a first layer and a second
layer, wherein the first amplifier element, the second amplifier
element, the first individual power supply path and the second
individual power supply path are provided on the first layer, and
the common power supply path is provided on the second layer.
5. The power amplifier according to claim 1, wherein the first
individual power supply path and the second individual power supply
path have different lengths.
6. The power amplifier according to claim 1, wherein the common
power supply path, the first individual power supply path and the
second individual power supply path each comprising an inductance
element.
7. A power amplifier comprising: a first amplifier element
configured to amplify a first input signal of a first frequency,
the first amplifier element including a first input terminal which
receives the first input signal, and a first output terminal which
outputs a first output signal obtained by amplifying the first
input signal; a second amplifier element configured to amplify a
second input signal of a second frequency, the second amplifier
element including a second input terminal which receives the second
input signal, and a second output terminal which outputs a signal
obtained by amplifying the second input signal; a power supply
input terminal connected to a direct-current power supply; a common
power supply path including an end connected to the power supply
input terminal, and another end; a first individual power supply
path including an end connected to the another end of the common
power supply path, and another end connected to the first output
terminal, the first individual power supply path having a first
impedance; a second individual power supply path including an end
connected to the another end of the common power supply path, and
another end connected to the second output terminal, the second
individual power supply path having a second impedance; a first
output matching circuit connected to the first output terminal of
the first amplifier element; and a second output matching circuit
connected to the second output terminal of the second amplifier
element.
8. The power amplifier according to claim 7, wherein: the first
amplifier element and the second amplifier element are controlled
exclusively to operate the first amplifier element and the second
amplifier element; and the common power supply path, the first
individual power supply path and the second individual power supply
path, the first output matching circuit and second output matching
circuit have respective impedances, each of the respective
impedances being set to a value so that a real part of a synthesis
impedance viewed from one selected from the first amplifier element
and second amplifier element that is in operation, to a
corresponding one selected from the first and second individual
power supply paths, is greater than a real part of a corresponding
one selected from the first output matching circuit and second
output matching circuit.
9. The power amplifier according to claim 7, wherein each of the
first output matching circuit and the second output matching
circuit has a conjugate impedance with respect to an impedance of a
corresponding one in operation of the first amplifier element and
the second amplifier element.
10. The power amplifier according to claim 7, further comprising a
multilayer wiring board including a first layer provided with the
first amplifier element and the second amplifier element, and a
second layer provided with the common power supply path and the
first individual power supply path and the second individual power
supply path.
11. The power amplifier according to claim 7, further comprising a
multilayer wiring board including first layer and second layer,
wherein the first amplifier element and the second amplifier
element are provided on the first layer, and the common power
supply path and the first individual power supply path and the
second individual power supply path are provided on the first layer
and the second layer.
12. The power amplifier according to claim 7, further comprising a
multilayer wiring board including first layer and second layer,
wherein the first amplifier element and the second amplifier
element and the first individual power supply path and the second
individual power supply path are provided on the first layer, and
the common power supply path is provided on the second layer.
13. The power amplifier according to claim 7, wherein the first
individual power supply path and the second individual power supply
path have different lengths.
14. The power amplifier according to claim 7, wherein the common
power supply path, the first individual power supply path and the
second individual power supply path each include an inductance
element.
15. A radio communication device which performs data reception and
transmission using one frequency band selected from a plurality of
frequency bands, comprising: a transmission signal generator which
generates a transmission signal of the one frequency band ; and the
power amplifier according to claim 1, the power amplifier receiving
the transmission signal as an input signal.
16. A radio communication device which performs data reception and
transmission using one frequency band selected from a plurality of
frequency bands, comprising: a transmission signal generator which
generates a transmission signal of the one frequency band; and the
power amplifier according to claim 7, the power amplifier receiving
the transmission signal as an input signal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2003-147917,
filed May 26, 2003, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a power amplifier mainly
for a high-frequency band, and more particularly to a power
amplifier that selectively amplifies a plurality of input signals
of different frequencies.
[0004] 2. Description of the Related Art
[0005] There exist radio communication systems for providing
services of mobile communication of a plurality of frequency bands.
In such systems, radio communication devices, such as mobile
terminals, are generally provided with the same number of
transmission signal power amplifiers as that of frequency bands
used.
[0006] For instance, in the personal digital cellular (PDC) system
that uses two frequency bands, two power amplifiers for the 800-MHz
band and 1900-MHz band are provided in a single mobile terminal.
Even a mobile terminal compatible with different systems, such as
an 800-MHz-band PDC and 1900-MHz-band personal handy-phone system
(PHS), is provided with power amplifiers dedicated to respective
frequency bands.
[0007] In a radio communication device, such as a mobile terminal
using a plurality of frequency bands, it is difficult to satisfy a
demand for size reduction if power amplifiers dedicated to the
respective frequency bands.
[0008] On the other hand, broadband amplifiers for use in measuring
devices can amplify signals of different frequency bands. This type
of amplifier, however, consumes much power, therefore is not
suitable for mobile terminals that use a battery as a power supply.
For this reason, they are not used in mobile terminals.
BRIEF SUMMARY OF THE INVENTION
[0009] It is an object of the invention to provide a power
amplifier for selectively amplifying signals of different frequency
bands, which can be made compact, and a radio communication device
using the power amplifier.
[0010] According to an aspect of the invention, there is provided a
power amplifier comprising: a first amplifier element configured to
amplify a first input signal of a first frequency, the first
amplifier element including a first input terminal which receives
the first input signal, and a first output terminal which outputs a
first output signal obtained by amplifying the first input signal;
a second amplifier element configured to amplify an input signal of
a second frequency, the second amplifier element including a second
input terminal which receives the input signal of the second
frequency, and a second output terminal which outputs a signal
obtained by amplifying the input signal of the second frequency; a
power supply input terminal connected to a direct-current power
supply; a common power supply path including an end connected to
the power supply input terminal, and another end; a first
individual power supply path including an end connected to the
another end of the common power supply path, and another end
connected to the first output terminal, the first individual power
supply path having a first impedance; and a second individual power
supply path-including an end connected to the another end of the
common power supply path, and another end connected to the second
output terminal, the second individual power supply path having a
second impedance.
[0011] According to another aspect of the invention, there is
provided a power amplifier similar to the above but further
comprising: a first output matching circuit connected to the first
output terminal of the first amplifier element; and a second output
matching circuit connected to the second output terminal of the
second amplifier element.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0012] FIG. 1A is a block diagram of a power amplifier according to
a first embodiment of the invention;
[0013] FIG. 1B shows a FET used for each amplifier element in FIG.
1A;
[0014] FIG. 1C shows a bipolar transistor used for each amplifier
element in FIG. 1A;
[0015] FIG. 2 is a diagram useful in explaining the impedance
relationship between components in the first embodiment, assumed
when an f1 amplifier element is operating;
[0016] FIG. 3 is a diagram useful in explaining the impedance
relationship between components in the first embodiment, assumed
when an f2 amplifier element is operating;
[0017] FIG. 4 illustrate the configuration of a power amplifier
according to a second embodiment of the invention;
[0018] FIG. 5 is a diagram useful in explaining the impedance
relationship between components in the second embodiment, assumed
when an f3 amplifier element is operating;
[0019] FIG. 6 shows a first structure example of a power supply
circuit incorporated in the first embodiment;
[0020] FIG. 7 shows a second structure example of the power supply
circuit incorporated in the first embodiment;
[0021] FIG. 8 shows a third structure example of the power supply
circuit incorporated in the first embodiment;
[0022] FIG. 9 shows a fourth structure example of the power supply
circuit incorporated in the first embodiment;
[0023] FIG. 10 shows a fifth structure example of the power supply
circuit incorporated in the first embodiment;
[0024] FIGS. 11A and 11B are schematic diagrams illustrating front
and back specific structure examples of the power amplifier of the
first embodiment;
[0025] FIGS. 12A, 12B and 12C are schematic diagrams illustrating
plural side specific structure examples of a power amplifier
according to a third embodiment;
[0026] FIG. 13 is a block diagram of a multi-stage power amplifier
according to a fourth embodiment; and
[0027] FIG. 14 is a block diagram of a radio communication device
according to a fifth embodiment.
DETAILED DESCRIPTION OF THE INVENTION
FIRST EMBODIMENT
[0028] FIG. 1A shows the configuration of a power amplifier
according to a first embodiment of the invention. The first
embodiment will be described using, as an example, a power
amplifier operable at two frequencies f1 and f2.
[0029] The power amplifier has input terminals 11 and 12 for
receiving input signals Vi1 and Vi2 of frequencies f1 and f2. The
input signal Vi1 is input to the input terminal of an f1 amplifier
element 17 via an input matching circuit 14. The input signal Vi2
is input to the input terminal of an f2 amplifier element 18 via an
input matching circuit 15. The signal amplified by the amplifier
element 17 is output as an output signal Vo1 from an output
matching circuit 21. Similarly, the signal amplified by the
amplifier element 18 is output as an output signal Vo2 from an
output matching circuit 22.
[0030] The amplifier elements 17 and 18 are formed of, for example,
the FET as shown in FIG. 1B, or the bipolar transistor as shown in
FIG. 1C. Further, each of the amplifier elements 17 and 18 is not
always formed of a single transistor, but may be formed of, for
example, two transistors connected in series. In FIG. 1A, reference
numerals 1, 2 and 3 denote the control electrode and first and
second main electrodes of the amplifier element 17. If the element
17 is formed of a FET, its gate electrode G, drain electrode D and
source electrode S correspond to the control electrode and first
and second main electrodes, respectively. Further, if the element
17 is formed of a bipolar transistor, its base electrode B,
collector electrode C and emitter electrode E correspond the
control electrode and first and second main electrodes,
respectively.
[0031] The signals output from the input matching circuits 14 and
15 are input to the respective control electrodes 1 of the
amplifier elements 17 and 18. The signals amplified are output from
the respective first main electrodes 2 of the amplifier elements 17
and 18. The second main electrodes 3 of the amplifier elements 17
and 18 are connected to a constant potential point (not shown), for
example, grounded.
[0032] The supply of power, i.e., a DC voltage, to the amplifier
elements 17 and 18 is performed by a power supply circuit described
below. Firstly, one end of a common power supply path 31 is
connected to a power supply input terminal 30 that is connected to
a DC power supply Vcc. The common power supply path 31 is connected
to both the amplifier elements 17 and 18. The other end of the
common power supply path 31 is connected to one end of each of
individual power supply paths 32 and 33 dedicated to the amplifier
elements 17 and 18, respectively. The other ends of the lines 32
and 33 are connected to the respective first main electrodes of the
amplifier elements 17 and 18. As described later, the individual
power supply paths 32 and 33 have different impedances.
[0033] The operation of the power amplifier of the first embodiment
will be described.
[0034] The f1 and f2 amplifier elements 17 and 18 operate at
different frequencies f1 and f2, as described above. However, they
are controlled such that they operate exclusively. In other words,
when one of the elements 17 and 18 is operating, the other is kept
inoperative.
[0035] The output matching circuit 21 matches impedances with a
circuit (not shown) connected after it, when the f1 amplifier
element 17 is operating at the frequency f1. The circuit 21 has a
conjugate impedance Z.sub.P1ON* with respect to the output
impedance Z.sub.P1ON of the amplifier element 17 during operation.
Similarly, the output matching circuit 22 matches impedances with a
circuit (not shown) connected after it, when the f2 amplifier
element 19 is operating at the frequency f2. The circuit 22 has a
conjugate impedance Z.sub.P2ON* with respect to the output
impedance Z.sub.P2ON of the amplifier element 18 during
operation.
[0036] The output matching circuits 21 and 22 do not necessarily
have conjugate impedances with respect to the output impedances of
the amplifier elements 17 and 18 during operation. They may be
adapted to different purposes. For instance, the impedances of the
output matching circuits 21 and 22 may be set so that the output
signals Vo1 and Vo2 have the maximum levels and/or the minimum
distortion values.
[0037] FIG. 2 shows the impedances of the components of FIG. 1A
assumed when the input signal Vi1 of the frequency f1 is input to
the input terminal 11, and the f1 amplifier element 17 is operating
and the f2 amplifier element 18 is not operating. The operating
amplifier element 17 has the output impedance Z.sub.P1ON. The first
main electrode (output terminal) of the amplifier element 17 is
connected to the output matching circuit 21 having the conjugate
impedance Z.sub.P1ON* with respect to Z.sub.P1ON, and is also
connected to the power supply circuit. The power supply circuit has
the common power supply path 31 and individual power supply paths
32 and 33, as described above. DC power is supplied to the f1
amplifier element 17 from the input terminal 30 via the common
power supply path 31 and individual power supply path 32.
[0038] On the other hand, the f2 amplifier element 18, which is not
operating, has an output impedance Z4. The impedance Z5 of the
output matching circuit 22 connected to the first main electrode
(output terminal) of the amplifier element 18 is identical to the
conjugate impedance Z.sub.P2ON* with respect to the output
impedance Z.sub.P2ON of the amplifier element 18 during
operation.
[0039] Assuming that the synthesis impedance when the power supply
circuit is viewed from the first main electrode of the operating f1
amplifier element 17 is Za, Za is given by 1 Z a = Z 1 ( Z 3 + Z 4
Z 5 Z 4 + Z 5 ) + Z 2 Z 2 ( Z 1 + Z 3 + Z 4 Z 5 Z 4 + Z 5 ) ( 1
)
[0040] where Z1 represents the impedance of the common power supply
path 31, Z2 and Z3 represent the impedances of the individual power
supply paths 32 and 33, and Z2.noteq.Z3. The impedances Z1, Z2 and
Z3 are expressed as a frequency function, Zn(f)=Rn(f)+Xn(f) (n=1,
2, 3). Rn(f) represents the resistance component, and Xn(f) the
reactance component. In equation (1) directed to the case where the
input signal Vi1 of the frequency f1 is input to the input terminal
11, and the f1 amplifier element 17 is operating, Z1, Z2 and Z3 are
Z1(f1), Z2(f1) and Z3(f1), respectively.
[0041] At this time, if the real part Re{Za} of the synthesis
impedance Za is set higher than the real part Re{Z.sub.P1ON*} of
the impedance Z.sub.P1ON* of the output matching circuit 21, as
shown in the following formula (2), the output signal (high
frequency power) of the amplifier element 17 is efficiently guided
to the output side via the output matching circuit 21, and output
as the output signal Vo1.
Re{Z.sub.a}>Re{Z.sub.P1ON*} (2)
[0042] The greater the difference between Re{Za} and
Re{Z.sub.P1ON*}, the higher the effect. If Re{Za} is five times or
more Re{Z.sub.P1ON*}, and more preferably if the former is ten
times or more the latter, the greater part of the high-frequency
power of the output signal of the f1 amplifier element 17 can be
output as the output signal Vo1.
[0043] FIG. 3 shows the impedances of the components of FIG. 1A
assumed when the input signal Vi2 of the frequency f2 is input to
the input terminal 12, and the f2 amplifier element 18 is operating
and the f1 amplifier element 17 is not operating. The operating
amplifier element 18 has the output impedance Z.sub.P2ON. The first
main electrode (output terminal) of the amplifier element 18 is
connected to the output matching circuit 22 having the conjugate
impedance Z.sub.P2ON* with respect to Z.sub.P2ON, and is also
connected to the power supply circuit. In the power supply circuit,
DC power is supplied to the f2 amplifier element 18 from the
input-terminal 30 via the common power supply path 31 and
individual power supply path 33.
[0044] On the other hand, the f1 amplifier element 17, which is not
operating, has an output impedance Z6. The impedance Z7 of the
output matching circuit 21 connected to the first main electrode
(output terminal) of the amplifier element 17 is identical to the
conjugate impedance Z.sub.P1ON* with respect to the output
impedance Z.sub.P1ON Of the amplifier element 17 during
operation.
[0045] Assuming that the synthesis impedance when the power supply
circuit is viewed from the first main electrode of the operating f2
amplifier element 18 is Zb, Zb is given by 2 Z b = Z 1 ( Z 2 + Z 6
Z 7 Z 6 + Z 7 ) + Z 3 Z 3 ( Z 1 + Z 2 + Z 6 Z 7 Z 6 + Z 7 ) ( 3
)
[0046] In equation (3) directed to the case where the input signal
Vi2 of the frequency f2 is input to the input terminal 12, and the
f2 amplifier element 18 is operating, Z1, Z2 and Z3 in the equation
(3) are Z1(f2), Z2(f2) and Z3(f2), respectively.
[0047] At this time, if the real part Re{Zb} of the synthesis
impedance Zb is set higher than the real part Re{Z.sub.P2ON*} of
the impedance Z.sub.P2ON* of the output matching circuit 22, as
shown in the following formula (4), the output signal (high
frequency power) of the amplifier element 18 is efficiently guided
to the output side via the output matching circuit 22, and output
as the output signal Vo2.
Re{Z.sub.b}>Re{Z.sub.P2ON*} (4)
[0048] Also in this case, if Re{Zb} is five times or more
Re{Z.sub.P2ON*}, and more preferably if the former is ten times or
more the latter, the greater part of the high-frequency power of
the output signal of the f2 amplifier element 18 can be output as
the output signal Vo2.
[0049] From the above formulas (1) to (4), Z1, Z2 and Z3 are
determined.
[0050] As described above, the power supply circuit for supplying
power to the amplifier elements 17 and 18 comprises the common
power supply path 31 commonly provided for the amplifier elements
17 and 18, and the individual power supply paths 32 and 33 provided
for the amplifier elements 17 and 18, respectively, and having
different impedances. By virtue of this structure, the power
amplifier can be made compact.
[0051] The advantage of the above structure will now be described.
Assume that the area of the common power supply path 31 is S1, and
those of the individual power supply paths 32 and 33 are S2 and S3,
respectively. In a power amplifier having a single amplifier
element operable at a single frequency, the power supply circuit
needs an area of (S1+S2) or (S1+S3) (i.e., the sum of the area S1
of the common power supply path and one of the areas S2 and S3 of
the individual power supply paths). Accordingly, where two
individual power supply circuits are provided for two amplifier
elements, an area of (2S1+S2+S3) is needed.
[0052] On the other hand, the area of the power supply circuit
employed in the embodiment is (S1+S2+S3), which is smaller by S1
than the case where individual power supply circuits are provided
for two amplifier elements. Since, in general, the power supply
circuit occupies a relatively large area in the power amplifier,
reduction of the area of the power supply circuit significantly
contributes to the reduction of the size of the power
amplifier.
[0053] In the embodiment, the output matching circuits 21 and 22
are set to have conjugate impedances with respect to the output
impedances of the amplifier elements 17 and 18 during operation,
respectively. However, the impedances of the circuits 21 and 22 are
not limited to the conjugate ones, but may be varied in accordance
with purposes.
SECOND EMBODIMENT
[0054] The power amplifier of the first embodiment is operable at
two frequencies f 1 and f2. However, a power amplifier that is
operable at three or more frequencies can be realized. In this
case, it is sufficient if the power amplifier comprises three or
more amplifier elements, a single common power supply path, three
or more individual power supply paths and three or more output
matching circuits. FIG. 4 shows a power amplifier according to a
second embodiment, which is operable at three frequencies f1, f2
and f3. In FIGS. 4 and 5, elements similar to those in FIG. 1A are
denoted by corresponding reference numerals.
[0055] The second embodiment employs a f3 amplifier element 19, as
well as the f1 and f2 amplifier elements 17 and 18. DC power input
to the power supply input terminal is supplied to one end of the
common power supply path 31. After that, the DC power is
distributed to the f1 amplifier element 17 via the individual power
supply path 32, to the f2 amplifier element 18 via the individual
power supply path 33, and to the f3 amplifier element 19 via the
individual power supply path 34. The individual power supply paths
32, 33 and 34 have different impedances, as will be described
later.
[0056] FIG. 5 shows the impedances of the components of FIG. 4
assumed when an input signal Vi3 of a frequency f3 is input to an
input terminal 13, and the f1 and f2 amplifier elements 17 and 18
are not operating and the f3 amplifier element 19 is operating. The
operating amplifier element 19 has an output impedance Z.sub.P3ON.
The first main electrode (output terminal) of the amplifier element
19 is connected to an output matching circuit 23 having a conjugate
impedance Z.sub.P3ON* with respect to Z.sub.P3ON, and is also
connected to the power supply circuit.
[0057] On the other hand, the f1 amplifier element 17, which is not
operating, has an output impedance Z6. The impedance Z7 of the
output matching circuit 21 connected to the first main electrode
(output terminal) of the amplifier element 17 is identical to the
conjugate impedance Z.sub.P1ON* with respect to the output
impedance Z.sub.P1ON of the amplifier element 17 during operation.
Similarly, the f2 amplifier element 18, which is not operating, has
an output impedance Z4. The impedance Z5 of the output matching
circuit 22 connected to the first main electrode (output terminal)
of the amplifier element 18 is identical to the conjugate impedance
Z.sub.P2ON* with respect to the output impedance Z.sub.P2ON Of the
amplifier element 18 during operation.
[0058] Assuming that the synthesis impedance when the power supply
circuit is viewed from the first main electrode of the operating f3
amplifier element 19 is Zc, Zc is given by 3 Z c = Z 8 + Z 1 ( Z 3
+ Z 4 Z 5 Z 4 + Z 5 ) ( Z 2 + Z 6 Z 7 Z 6 + Z 7 ) ( Z 3 + Z 4 Z 5 Z
4 + Z 5 ) ( Z 2 + Z 6 Z 7 Z 6 + Z 7 ) + Z 1 + ( Z 3 + Z 4 Z 5 Z 4 +
Z 5 ) + Z 1 ( Z 2 + Z 6 Z 7 Z 6 + Z 7 ) ( 5 )
[0059] In equation (5) directed to the case where the input signal
Vi3 of the frequency f3 is input to the input terminal 13, and the
f3 amplifier element 19 is operating, Z1, Z2 and Z3 are Z1(f3),
Z2(f3) and Z3(f3), respectively.
[0060] Similarly, the synthesis impedance Za, obtained if the power
supply circuit is viewed from the first main electrode of the f1
amplifier element 17 when the element 17 is operating and the
elements 18 and 19 are not operating, is given by the following
equation (6). The synthesis impedance Zb, obtained if the power
supply circuit is viewed from the first main electrode of the f2
amplifier element 18 when the element 18 is operating and the
elements 17 and 19 are not operating, is given by the following
equation (7). 4 Z a = Z 2 + Z 1 ( Z 3 + Z 4 Z 5 Z 4 + Z 5 ) ( Z 8 +
Z 9 Z 10 Z 9 + Z 10 ) ( Z 3 + Z 4 Z 5 Z 4 + Z 5 ) ( Z 8 + Z 9 Z 10
Z 9 + Z 10 ) + Z 1 + ( Z 3 + Z 4 Z 5 Z 4 + Z 5 ) + Z 1 ( Z 8 + Z 9
Z 10 Z 9 + Z 10 ) ( 6 ) Z b = Z 3 + Z 1 ( Z 2 + Z 6 Z 7 Z 6 + Z 7 )
( Z 8 + Z 9 Z 10 Z 9 + Z 10 ) ( Z 2 + Z 6 Z 7 Z 6 + Z 7 ) ( Z 8 + Z
9 Z 10 Z 9 + Z 10 ) + Z 1 + ( Z 2 + Z 6 Z 7 Z 6 + Z 7 ) + Z 1 ( Z 8
+ Z 9 Z 10 Z 9 + Z 10 ) ( 7 )
[0061] In equation (6) directed to the case where the input signal
Vi1 of the frequency f1 is input to the input terminal 11, and the
f1 amplifier element 17 is operating, Z1, Z2 and Z3 are Z1(f1),
Z2(f1) and Z3(f1), respectively. Similarly, in equation (7)
directed to the case where the input signal Vi2 of the frequency f2
is input to the input terminal 12, and the f2 amplifier element 18
is operating, Z1, Z2 and Z3 are Z1(f2), Z2(f2) and Z3(f2),
respectively.
[0062] In those cases, if the real parts Re{Za}, Re{Zb} and Re{Zc}
of the synthesis impedances Za, Zb and Zc are set higher than the
real parts Re{Z.sub.P1ON*}, Re{Z.sub.P2ON*} and Re{Z.sub.P3ON*} of
the impedances Z.sub.P1ON*, Z.sub.P2ON* and Z.sub.P3ON* of the
output matching circuits 21, 22 and 23, respectively, as shown in
the following formulas (8), (9) and (10), the output signals (high
frequency power) of the amplifier elements 17, 18 and 19 are
efficiently guided to the output side via the output matching
circuits 21, 22 and 23, and output as the output signals Vo1, Vo2
and Vo3, respectively.
Re{Z.sub.a}>Re{Z.sub.P1ON*} (8)
Re{Z.sub.b}>Re{Z.sub.P2ON*} (9)
Re{Z.sub.c}>Re.dbd.Z.sub.P3ON*} (10)
[0063] From the formulas (1) to (10), Z1, Z2 and Z3 are determined.
Even in the case of a power amplifier including four or more
amplifier elements, the impedances of the common power supply path
and individual power supply paths can be determined by executing
the same procedure as the above.
[0064] Moreover, as in the first embodiment, if the real parts
Re{Za}, Re(Zb) and Re(Zc) of the synthesis impedances Za, Zb and Zc
are five times or more Re{Z.sub.P1ON*}, Re{Z.sub.P3ON*} and
Re{Z.sub.P2ON*}, respectively, and more preferably if the formers
are ten times or more the latters, the greater part of the
high-frequency power of the output signals of the f1, f2 and f3
amplifier elements 17, 18 and 19 can be output as the output
signals Vo1, Vo2 and Vo3.
[0065] A description will be given of more specific power amplifier
examples according to the first and second embodiments.
[0066] FIG. 6 shows a first example of the power amplifier of the
first embodiment that is operable at the frequencies f1 and f2. In
this example, the power supply circuit is formed of a plurality of
spiral inductors. A spiral inductor 41 corresponds to the common
power supply path 31, and spiral inductors 42 and 43 correspond to
the individual power supply paths 32 and 33, respectively. The
impedances of the spiral inductors 41, 42 and 43 are given by
Z.sub.1=R.sub.1+j.omega.X.sub.1 (11)
Z.sub.2=R.sub.2+j.omega.X.sub.2 (12)
Z.sub.3=R.sub.3+j.omega.X.sub.3 (13)
[0067] where R1, R2 and R3 represent the resistance components, and
X1, X2 and X3 the reactance components. R1, R2, R3, X1, X2 and X3
can be determined by combining the equations (11), (12) and (13)
with the formulas (1), (2), (3) and (4), and setting an appropriate
frequency.
[0068] FIG. 7 shows a second example of the power amplifier of the
first embodiment. In this example, the power supply circuit is
formed of meander lines and capacitors. A meander line 51
corresponds to the common power supply path 31, and meander lines
52 and 53 correspond to the individual power supply paths 32 and
33, respectively. Capacitors 54, 55 and 56 are provided between the
input terminals of the meander lines 51, 52 and 53 and the earth,
respectively.
[0069] FIG. 8 shows a third example of the power amplifier of the
first embodiment. In this example, the power supply circuit is
formed of transmission lines and bonding wires. A straight
transmission line 61A, T-shaped transmission line 61B and boding
wire 64 connecting them provide a common power supply path
corresponding to the common power supply path 31 in FIG. 1A. The
T-shaped transmission line 61B, transmission line 62 and boding
wire 65 connecting them provide an individual power supply path
corresponding to the individual power supply path 32 in FIG. 1A.
Similarly, the T-shaped transmission line 61B, transmission line 63
and boding wire 66 connecting them provide an individual power
supply path corresponding to the individual power supply path 33 in
FIG. 1A. Desired impedances can be obtained by changing the lengths
and/or thicknesses of the bonding wires 64, 65 and 66.
[0070] FIG. 9 shows a fourth example of the power amplifier of the
first embodiment. In this example, the power supply circuit is
formed of chip components that include capacitors and inductors. A
capacitor 71 and inductor 72 provide a common power supply path
corresponding to the common power supply path 31 in FIG. 1A. A
capacitor 73 and inductor 74 provide an individual power supply
path corresponding to the individual power supply path 32 in FIG.
1A, while a capacitor 75 and inductor 76 provide an individual
power supply path corresponding to the individual power supply path
33 in FIG. 1A.
[0071] FIG. 10 shows a fifth example of the power amplifier of the
first embodiment. In this example, the power supply circuit is
formed of inductors or median lines using via holes. Specifically,
wiring layers 81 and 82 on the upper and lower surfaces of a plate
80 called a module plate, respectively. Each of the wiring layers
81 and 82 has a transmission line 83 of a predetermined pattern.
The upper and lower surfaces of the substrate 80 are connected to
each other by via holes 84, thereby forming inductors or median
lines.
[0072] Also in the second to fifth examples, R1, R2, R3, X1, X2 and
X3 can be determined by combining the equations (11), (12) and (13)
with the formulas (1), (2), (3) and (4), and setting an appropriate
frequency.
[0073] FIGS. 11A and 11B shows front and back structures of a sixth
example of the power amplifier of the first embodiment,
respectively. In this example, the amplifier elements and power
supply circuit are provided on different layers of a multilayer
substrate. Specifically, the f1 and f2 amplifier elements 17 and 18
and individual power supply paths 32 and 33 are provided on the
upper surface of a multilayer substrate 90, while the common power
supply path 31 is provided on the lower surface of the substrate
90.
THIRD EMBODIMENT
[0074] FIGS. 12A ,12B and 12C show, respectively, plural structures
of a power amplifier according to a third embodiment that is
operable at the four frequencies f1, f2, f3 and f4. This power
amplifier employs the structure shown in FIG. 11A and 11B.
Specifically, f1 and f2 amplifier elements 17 and 18 and individual
power supply paths 22 and 23 are provided on the upper surface 91
of a multilayer substrate. A common power supply path 21 is
provided on the intermediate layer 92 of the substrate. Further, f3
and f4 amplifier elements 19 and 20 and individual power supply
paths 24 and 25 are provided on the lower surface 93 of the
substrate.
FOURTH EMBODIMENT
[0075] FIG. 13 shows a power amplifier according to a fourth
embodiment of the invention. The power amplifiers of the first and
second embodiments have a single-stage structure, while the power
amplifier of the fourth embodiment has a dual-stage structure.
[0076] In the fourth embodiment, input signals Vi1 and Vi2 of
frequencies f1 and f2, supplied to input terminals 11 and 12, are
input to the first-stage f1 and f2 amplifier elements 17A and 18A
via input matching circuits 14 and 15, respectively. The outputs of
the first-stage f1 and f2 amplifier elements 17A and 18A are input
to the second-stage f1 and f2 amplifier elements 17B and 18B via
intermediate matching circuits 24 and 25, respectively. The outputs
of the second-stage f1 and f2 amplifier elements 17B and 18B are
extracted as output signals Vo1 and Vo2 via output matching
circuits 21 and 22, respectively.
[0077] DC power is supplied to the first-stage f1 and f2 amplifier
elements 17A and 18A via a first power supply circuit that has a
common power supply path 31A and individual power supply paths 32A
and 33A. Similarly, DC power is supplied to the second-stage f1 and
f2 amplifier elements 17B and 18B via a second power supply circuit
that has a common power supply path 31B and individual power supply
paths 32B and 33B. The fourth embodiment can be modified into a
power amplifier including a three-stage or more structure.
FIFTH EMBODIMENT
[0078] A description will be given of a radio communication device
according to a fifth embodiment of the invention, in which the
power amplifier of the first embodiment is incorporated in the
transmission system of the device. FIG. 14 shows the configuration
of a radio communication device operable at two frequency
bands.
[0079] Firstly, the receiving system of the device will be
described. An RF reception signal received by an antenna 100 is
guided to the receiving system via a duplexer 101, and distributed
into two receiving routes by a switch 102 in accordance with its
frequency. If the RF signal is distributed into a first receiving
route, it is guided to a mixer 107 via a band-pass filter (OPF) 103
and low noise amplifier (LNA) 105, and is subjected to frequency
conversion based on a local signal from a local signal source 109,
i.e., it is down-converted.
[0080] The output signal of the mixer 107 is simultaneously input
to two mixers 112 and 113 via a band-pass filter 110. The mixers
112 and 113 provide an orthogonal demodulator, receive orthogonal
local signals from a local signal source 114, and convert the
signals, supplied from the band-pass filter 110, into orthogonal
reception baseband signals, i.e., I and Q signals. The orthogonal
reception baseband signals are input to a baseband processing unit
120, where they are reproduced as received data.
[0081] A second receiving route is similar to the first one, and
comprises a band-pass filter 104, low noise amplifier 106, mixer
108, band-pass filter 108, mixers 115 and 116, and local signal
source 117. The local signal source 117 generates local signals of
a frequency different from that of the local signals generated by
the local signal source 114.
[0082] The transmission system will now be described. The baseband
processing unit 120 performs digital signal processing on
transmission data, thereby generating orthogonal transmission
baseband signals, i.e., I and Q signals. The generated I/Q signals
are input to one of the transmission routes in accordance with
their transmission frequency. If the I/Q signals are input to a
first transmission route, they are multiplied, in mixers 121 and
122, by the respective orthogonal local signals from a local signal
source 123. The output signals of the mixers 121 and 122 are added
by an adder 127. The mixers 121 and 122 and adder 127 form an
orthogonal modulator.
[0083] The output signal of the adder 127 is guided to a mixer 129,
where it is subjected to frequency conversion based on a local
signal from a local signal line 131, i.e., it is up-converted. The
output signal of the mixer 129 is supplied to a band-pass filter
132, where an unnecessary component is eliminated therefrom. After
that, the resultant signal is amplified by a power amplifier 134.
The output signal of the power amplifier 134 is guided to a switch
137 via a low-pass filter 135, and then to the antenna 100 via the
duplexer 101. Thus, the signal is output as an electric wave from
the antenna.
[0084] The other transmission route, i.e., a second route, is
similar to the first one, and comprises mixers 124 and 125 and
adder 128 providing an orthogonal modulator, local signal source
126 for the orthogonal modulator, mixers 129 and 130 and local
signal line 131 for up-conversion, band-pass filter 133, power
amplifier 134 and low-pass filter 136. The transmission frequency,
i.e., the frequency of a transmission signal input to the power
amplifier 134, differs from that of the first transmission
route.
[0085] If the power amplifier of the first embodiment is used as
the power amplifier 134, it can be commonly used for two
transmission routes. This being so, the whole area required for the
power amplifier can be reduced compared to the case where
respective power amplifiers are used for two transmission routes,
which contributes to the reduction of the size and cost of the
radio communication device. Further, a radio communication device
having three or more frequencies can be realized by modifying the
configuration of FIG. 14.
[0086] Additional advantages and modifications will readily occur
to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and
representative embodiments shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *