JPH11220337A - Power amplifier - Google Patents

Abstract

(57) [Problem] To provide a small-sized power amplifier with little characteristic fluctuation due to impedance on a power supply side. The power amplifier includes a field effect transistor or a bipolar transistor as an amplifying element Tr1, a gate or base serving as a signal input side of the amplifying element Tr1, a drain or collector serving as a signal output side, and a bias supply power supply Vbb. , Vcc, the inductance elements L1 and L2 and the capacitance element C
1 and C2 and choke circuits 3 and 4 including resistance elements R1 and R2 are connected. Even when the choke circuits 3 and 4 resonate with the power supply impedance at a frequency having an inductive or capacitive component, the resistance elements R1 and R2 keep the resonance Q value low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to mobile communication,
The present invention relates to a power amplifier used in satellite communication and the like.

[0002]

2. Description of the Related Art Generally, in a circuit configuration of a power amplifier, a choke circuit is used for the purpose of connecting an external bias supply power supply and a power amplifier in a DC manner and separating them in a high frequency. In order to achieve the above object, in the operating frequency band of the power amplifier, the impedance of the choke circuit is made higher than the impedance seen from the choke circuit to the power amplifier side, so that the impedance on the power supply side affects the characteristics of the power amplifier. It is necessary not to give.

[0003] As a configuration of a conventional small choke circuit,
For example, there is one disclosed in JP-A-8-840303. Extracting the choke circuit part of this conventional example,
As shown in FIG.

In FIG. 5, Tr100 is a transistor as an amplifying element, L100 is an inductor, C100,
C200 is a capacitor. Vcc is a bias supply power supply. Normally, C100 is not used, and the inductance value of the inductor L100 is increased by increasing the inductance value of the inductor L100. The choke circuit is designed to be larger than that of the choke circuit.

On the other hand, in this conventional example, L100 and C
100, the impedance Z of the parallel circuit is set to ZP = jωL100 / (1− (ωL100 · C100) ² ). With the addition of C100, ZP equivalent to ZL is realized with a small L100, and an inductor having a large area occupied by a capacitor is reduced in size, thereby reducing the size of the choke circuit. The grounding capacitor C20
0 is inserted to fix the impedance when the power supply side is viewed from the choke circuit in a state close to a short circuit, regardless of the state of the impedance on the power supply side.

[0006]

However, the above conventional example has the following problems to be solved. First, at the resonance frequency of the parallel circuit CK forming the resonance circuit in FIG. 5, ZP becomes infinite, so that the ground capacitor C
Regardless of the presence or absence of 200, the amplification element Tr1 and the power supply side are separated in terms of high frequency.

However, at frequencies other than the resonance frequency, the parallel circuit CK has an inductive or capacitive impedance. For this reason, the parallel circuit CK resonates with the impedance on the power supply side in the operating frequency band, impairing the high-frequency separation between the power supply and the power amplifier, increasing impedance mismatch in the power amplifier and causing oscillation. May have adverse effects.

The above problem is reduced by increasing the capacitance value of the ground capacitor C200 to a value close to a short-circuit state at high frequencies. However, in an actual chip capacitor, it is difficult to achieve an ideal grounding state because there are parasitic inductances such as an inductance of the capacitor itself and a wiring inductance of a path to ground.

Further, as the operating frequency of the power amplifier becomes higher, the effect of the parasitic inductance becomes larger, so that the problem becomes more serious. Here, the ground capacitor C2
Is monolithically formed on the semiconductor chip on which the amplifying element Tr1 is formed, the parasitic inductance is reduced.
However, if an attempt is made to achieve a sufficient grounding state, the area occupied by the capacitor C200 increases, the size of the semiconductor chip increases, and it becomes difficult to reduce the chip cost.

An object of the present invention is to solve the above-mentioned problems, and to provide a small power amplifier in which the characteristic fluctuation due to the impedance on the power supply side is small.

[0011]

According to a first aspect of the present invention, there is provided a power amplifier comprising at least one of a signal input side or a signal output side of an amplifying element and a bias supply power supply of the amplifying element. A choke circuit including an inductance element, a capacitance element, and a resistance element is connected therebetween.

In the first aspect of the present invention, a choke circuit including an inductance element L, a capacitance element C, and a resistance element R is connected between the bias supply power supply and the amplification element. Therefore, even when the choke circuit resonates with the power source impedance at a frequency at which the impedance of the choke circuit has an inductive or capacitive component,
The resistance element R keeps the Q value of the resonance low. As a result, it is possible to suppress a variation in impedance when the bias supply power supply including the choke circuit is viewed from the amplifying element, and it is possible to suppress occurrence of impedance mismatch and oscillation of the power amplifier.

According to a second aspect of the present invention, in the power amplifier according to the first aspect, the amplifying element is a field effect transistor or a bipolar transistor, and is made of a silicon semiconductor or a compound semiconductor. And

According to the second aspect of the present invention, the size of the amplifier can be reduced by using a field-effect transistor or a bipolar transistor made of a silicon semiconductor or a compound semiconductor.

According to a third aspect of the present invention, in the power amplifier according to the first or second aspect, the choke circuit comprises:
It is characterized in that the inductance element, the capacitance element, and the resistance element are configured as a parallel circuit connected in parallel with each other.

In the third aspect of the present invention, assuming that the inductance, capacitance, and resistance of the inductance element, the capacitance element, and the resistance element are L, C, and R, respectively, the impedance Zt of the parallel circuit is Zt = (ωL) ² R / (R ² (1−ω ² LC) ² + (ωL) ² ) + jωLR ² (1−ω ² LC) / (R ² (1−ω ² LC) ² + (ωL) ² ) = Re ( Zt) + jIm (Zt) (Re (Zt): real part of Zt, Im (Zt): imaginary part of Zt) Re (Zt) = (ωL) ² R / (R ² (1−ω ² LC) ² + (ωL) ² ) Im (Zt) = ωLR ² (1−ω ² LC) / (R ² (1−ω ² LC) ² + (ωL) ² ), and there is a real part also in high frequency.

Therefore, regardless of the value of the impedance on the power supply side, the impedance when viewing the bias supply power supply side including the parallel circuit from the amplifying element becomes equal to or greater than the real part Re (Zt) of the impedance Zt. Limited. Therefore, the impedance fluctuation when viewing the bias supply power supply side including the parallel circuit from the amplification element is suppressed.

The real part Re (Zt) of the impedance Zt
Since it affects high-frequency loss, it is desirable that the value be as large as possible at the operating frequency of the power amplifier. Therefore, as is clear from the notation of Re (Zt), it is desirable that the resonance frequency of the LC is near the operating frequency of the power amplifier. In addition, if it is necessary to reduce the difference between the LC resonance frequency and the real part of Zt at other frequencies and extend the band, R may be reduced. If it is necessary to increase the real part of Zt near the resonance frequency, R may be increased. The value of R may be set as necessary in consideration of these.

Further, since a DC current supplied from the bias supply power supply to the amplifying element flows through the inductance element L, no DC loss occurs due to the resistance element R. Further, as described above, the capacitance value of the capacitance element C connected in parallel with the inductance element L allows the inductance value of the inductance element L to be reduced and the size of the inductance element L to be reduced.

According to a fourth aspect of the present invention, in the power amplifier according to the first or second aspect, the choke circuit includes a series connection circuit in which the capacitance element and the resistance element are connected in series, and an inductance element in parallel. , And is characterized by being constituted by a circuit connected to.

According to the fourth aspect of the present invention, since no DC current flows through the resistance element, DC power consumption at the resistance element is eliminated.

Further, the invention of claim 5 provides the invention according to claims 1 to 4
In the power amplifier according to any one of the above, the resonance frequency of the choke circuit is set higher than the operating frequency of the amplifying element.

According to the fifth aspect of the present invention, the resonance frequency of the choke circuit at which the real part Re (Zt) of the impedance Zt of the choke circuit is maximized is set higher than the operating frequency of the power amplifier. The inductance element or the capacitance element of the choke circuit can be reduced as compared with the case where resonance occurs at the operating frequency. Therefore, according to the invention of claim 5, further downsizing can be achieved. In the non-resonant state, the possibility that the choke circuit resonates with the power source side impedance at the above operating frequency increases. However, since the Q value of the choke circuit is reduced by the resistance element, the impedance due to this resonance is lower than that of the conventional example. Fluctuations are also suppressed.

Also, the invention of claim 6 is the invention of claims 1 to 5
In the power amplifier according to any one of the above, at a frequency at which the amplification element operates, a resistance value of the resistance element or a real part of an impedance of the choke circuit is set higher than an input impedance or an output impedance of the amplification element. In addition, the input impedance and the output impedance are set to 100 times or less.

According to the present invention, the resistance value R of the resistance element or the real part Re (Zt) of the impedance of the choke circuit is set higher than the input impedance or output impedance of the amplification element at the operating frequency of the power amplifier. did.

Thus, power consumption by the resistance element can be suppressed, and the gain of the power amplifier can be improved. If the resistance value R of the resistance element is lower than the input impedance or the output impedance, the resistance element absorbs at least half or more of the power input to the amplification element or the power output from the amplification element, This results in a reduction in the gain of the power amplifier. It is more desirable that the resistance value R of the resistance element be higher than three times the input impedance or the output impedance.

On the other hand, since the resistance value R of the resistance element is set to 100 times or less of the input impedance or the output impedance of the amplification element, the real part Re (Zt) of the impedance Zt of the choke circuit at a frequency other than the resonance frequency.
Can be prevented from rapidly decreasing, and the influence of the impedance on the power supply side can be reduced. If the resistance value R of the resistance element is excessively increased, the real part Re of the impedance Zt of the choke circuit at a frequency other than the resonance frequency.
(Zt) sharply decreases, and is easily affected by the impedance on the power supply side.

Further, the invention of claim 7 provides the invention according to claims 1 to 6
In the power amplifier according to any one of the above, a multi-stage power amplifier having a plurality of amplification elements, wherein a choke circuit including the inductance element, the capacitance element, and the resistance element is shared by two or more amplification stages. It is characterized by being.

According to the seventh aspect of the present invention, since the choke circuit is shared by two or more amplifying stages, the number of choke circuits can be reduced and the power amplifier can be downsized.

Further, the invention of claim 8 provides the invention according to claims 1 to 7
In the power amplifier according to any one of the above, the choke circuit is formed on the same semiconductor substrate together with the amplifying element.

According to the present invention, since the choke circuit is formed on the same semiconductor substrate together with the amplifying element, the choke circuit and the amplifying element can be connected by a short wiring. , And the parasitic capacitance between the wiring and the ground can be reduced, and a small power amplifier with further less characteristic fluctuation can be realized.

When the circuit including the inductance element, the capacitance element, and the resistance element is monolithically formed on a semiconductor substrate, the inductance element and the capacitance element can be configured by a spiral inductor or a MIM capacitor. Therefore, the size can be reduced as compared with the case of using a chip inductor or a chip capacitor, and the size of the entire power amplifier can be reduced. Further, in the present invention, if the ground capacitance C2 in FIG. 5 of the conventional example is regarded as a part of the impedance on the power supply side, it is clear that it is not necessary to make C2 monolithic, and without increasing the chip area. And chip cost can be reduced. Further, the inductance element and the capacitance element in the choke circuit according to the present invention may be impedance elements showing inductive and capacitive, respectively, and these may be constituted by distributed constant elements such as microstrip lines. .

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

[First Embodiment] FIG. 1 shows a first embodiment of the power amplifier of the present invention. This power amplifier includes an input matching circuit 1 to which a signal is input, a transistor Tr1 as an amplifying element, and an output matching circuit 2 to output a signal. The transistor Tr1 is connected between the input matching circuit 1 and the output matching circuit 2. And
Connection line 7 between input matching circuit 1 and transistor Tr1
The first choke circuit 3 is connected between the power supply and the bias power supply Vbb. A second choke circuit 4 is connected between the power supply Vcc and a connection line 8 between the output matching circuit 2 and the transistor Tr1.

The first choke circuit 3 comprises a parallel circuit of a resistance element R1, an inductance element L1, and a capacitance element C1. The second choke circuit 4 is configured by a parallel circuit of a resistance element R2, an inductance element L2, and a capacitance element C2.

In FIG. 1, a signal is input from an input side of a transistor TR1 as an amplifying element of the power amplifier via an input matching circuit 1. The above transistor TR1
Is an FET (field effect transistor), the gate terminal side is the input side, and the transistor TR1
Is a bipolar transistor, the base terminal side is the input side.

A signal is output from the output side of the transistor TR1 via the output matching circuit 2. If the transistor TR1 is an FET, the drain terminal side is the output side, and if the transistor TR1 is a bipolar transistor, the collector terminal side is the output side.

The transistor TR1 as an amplifying element is
It is formed using a silicon semiconductor or a compound semiconductor such as GaAs. The inductance elements L1 and L2
Is formed by a wiring inductor such as a chip inductor or a spiral inductor formed on a substrate. Further, the capacitance elements C1 and C2 are chip capacitors or MIM (metal / metal) formed on the substrate.
It is formed by an insulator metal) capacitor and the like. The substrate includes a semiconductor substrate, alumina,
A ceramic substrate such as aluminum nitride or a glass epoxy or Teflon substrate is used.

In the power amplifier having the above configuration, the amplifying element TR
1 to the bias power supply V including the choke circuits 3 and 4
The real part of the impedance looking at the bb side is the power supply Vbb, Vbb
Regardless of the value of the impedance on the cc side, the resistance of the choke circuits 3 and 4 is limited to a value equal to or greater than the real part by the resistance elements R1 and R2. For this reason, it is possible to suppress the impedance variation when the bias supply power supply Vbb side including the choke circuits 3 and 4 is viewed from the amplifier element Tr1, and it is possible to suppress the occurrence of the impedance mismatch and the oscillation of the amplifier element Tr1. Moreover, since the DC current supplied from the bias supply power supply Vbb or the power supply Vcc to the amplification element Tr1 flows through the inductance elements L1 and L2, no DC loss occurs due to the resistance element R1 or R2.

Further, by connecting the inductance elements L1 and L2 of the choke circuits 3 and 4 and the capacitance elements C1 and C2 in parallel, the inductance elements L1 and L2 occupying a large area can be reduced in size, and the entire power amplifier can be reduced in size. it can.

The choke circuits 3 and 4 are connected to the amplifying element T
When the semiconductor substrate on which r1 is formed is made monolithic, the choke circuits 3, 4 and the amplifying element Tr1 can be connected by a short wiring. Therefore, the parasitic inductance of the wiring and the parasitic capacitance between the wiring and the ground can be reduced. Therefore, the choke circuits 3 and 4 can more effectively suppress the impedance fluctuation, and can prevent impedance mismatch and oscillation.

When the choke circuits 3 and 4 are monolithically formed on a semiconductor substrate,
4 can be formed using a spiral inductor or MIM capacitor that is smaller than a chip inductor or chip capacitor. Therefore, the size of the entire power amplifier can be reduced.

When the resonance frequencies of the choke circuits 3 and 4 are set higher than the operating frequency of the power amplifier Tr1, the size of the inductance elements L1 and L2 and the capacitance elements C1 and C2 can be reduced. In this case,
In the non-resonant state, there is a high possibility that the choke circuits 3 and 4 will resonate with the power source side impedance at the above operating frequency,
Since the Q value of the choke circuit is reduced by the resistance elements R1 and R2, impedance fluctuation due to this resonance can be suppressed.

At the operating frequency of the power amplifier, the real part of the impedance of the choke circuits 3 and 4 or the resistance values of the resistance elements R1 and R2 are respectively determined by the amplification element T
r1 is set to be higher than the input impedance or output impedance and 100 times or less of the input or output impedance.

By setting the resistance values of the resistance elements R1 and R2 higher than the input / output impedance, the resistance element R
1, the power consumption in R2 can be suppressed, and a decrease in the gain of the amplification element Tr1 can be suppressed. It is practically desirable to set the resistance values of the resistance elements R1 and R2 to three times or more of the input and output impedances.

By setting the resistance values of the resistance elements R1 and R2 to 100 times or less of the input and output impedances, the real part Re (Zt) of the impedance Zt of the choke circuits 3 and 4 at a frequency other than the resonance frequency. Can be prevented from rapidly decreasing, and the influence of the impedance on the power supply side can be reduced.

[Second Embodiment] Next, FIG. 2 shows a second embodiment of the present invention. The second embodiment is different from the first embodiment in that a circuit 15 constituting a part of the input matching circuit is connected between the first choke circuit 3 and the connection line 7, and the second choke circuit 4 and the connection line 8 Is different from the first embodiment in that a circuit 16 forming a part of the output matching circuit is connected between the first and second embodiments.

The circuit 15 includes an inductance element Lm1 connected between the first choke circuit 3 and the connection line 7.
And a capacitor Cm1 connected between the bias power supply side of the inductance element Lm1 and the ground. The circuit 16 includes an inductance element Lm2 connected between the second choke circuit 4 and the connection line 8.
And a capacitor Cm2 connected between the bias power supply side of the inductance element Lm2 and the ground.

The capacitors Cm1 and Cm2 are
Input / output matching circuits 15 and 16 and bias supply power supply Vbb
May be used as a ground capacitor for improving high-frequency isolation from the capacitor.

The structure of the first and second choke circuits 3 and 4 in the second embodiment is the same as that of the first embodiment.
It is possible to suppress a change in impedance when the power supply side is viewed from the amplifying element Tr1, thereby preventing impedance mismatching and oscillation.

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention. In the third embodiment, amplifying elements Tr1 and Tr constituting a two-stage high-frequency amplifier
2 is different from the above-described first and second embodiments. The amplification elements Tr1 and Tr2 are connected by a connection line 19, and the connection line 19 is provided with an interstage matching circuit 17.

The point that the circuit 15 is connected between the connection line 7 connecting the input matching circuit 1 and the amplifying element Tr1 and the first choke circuit 3 is the same as in the second embodiment.

In the third embodiment, a circuit 18 constituting a part of the inter-stage matching circuit is connected between the second choke circuit 4 and the connection line 19, and the second choke circuit 4
A circuit 16 constituting a part of an output matching circuit is connected between the circuit 16 and the connection line 8. The circuit 18 includes an inductance element Lm3 connected between the connection line 19 and the second choke circuit 4, and a capacitor Cm3 connected between the power supply side of the inductance element Lm3 and the ground.
have.

In the third embodiment, two amplifying elements T
The output sides of r1 and Tr2 are connected to a bias supply power supply Vc via a second choke circuit 4 including a parallel circuit of an inductance element L2, a capacitance element C2, and a resistance element R2.
c.

As described above, in the third embodiment, the output sides of the two amplifying elements Tr1 and Tr2 are connected to the bias supply power supply Vcc by one choke circuit 4. Therefore, the circuit can be simplified as compared with the case where the output sides of the amplification elements Tr1 and Tr2 are connected to the power supply Vcc by separate choke circuits, and the size can be reduced.

In the third embodiment, the output sides of the two amplifying elements Tr1 and Tr2 are connected to the bias supply power supply Vcc by one choke circuit 4, but the input sides of the two amplifying elements Tr1 and Tr2 are connected. May be connected to the bias supply power supply Vbb by one choke circuit 3.

The number of amplifying elements (number of amplifying stages) shared by the choke circuit 4 may be three or more. Further, instead of the two capacitors Cm2 and Cm3, a capacitor having the sum capacitance of both capacitors may be connected between the terminal 4A on the amplifying element side of the choke circuit 4 and the ground. Then, the capacitor having the above sum capacitance may be used as a ground capacitor for improving the high-frequency separation between the interstage matching circuit 17 or the output matching circuit 2 and the bias supply power supply Vcc.

In the first, second and third embodiments described above, the first choke circuit 3 composed of L1, C1, R1 and the second choke circuit 4 composed of L2, C2, R2 are replaced with the drawings. 4A, a first choke circuit 33 and a second choke circuit 34 may be provided. The first choke circuit 33 includes a series circuit of a resistance element R1 and a capacitor C1, and an inductance element L1 connected in parallel to the series circuit. The second choke circuit 34 includes a series circuit of a resistance element R2 and a capacitor C2, and an inductance element L2 connected in parallel to the series circuit.

The first and second choke circuits 3 and 4
Instead, a first choke circuit 43 and a second choke circuit 44 shown in FIG. 4B may be provided. The first choke circuit 43 is configured by a circuit in which a parallel circuit of a capacitor C1 and an inductance element L1 is connected in series to a resistance element R1. The second choke circuit 44 is configured by a circuit in which a parallel circuit of a capacitor C2 and an inductance element L2 is connected in series to a resistance element R2.

The first and second choke circuits 3 and 4
Instead, a first choke circuit 53 and a second choke circuit 54 shown in FIG. 4C may be provided. The first choke circuit 53 includes a capacitor C1 and an inductance element L
1 and a circuit in which a series circuit of a resistance element R1 is connected in parallel. The second choke circuit 53 is configured by a circuit in which a series circuit of an inductance element L2 and a resistance element R2 is connected in parallel to a capacitor C2.

The first and second choke circuits 3 and 4
Instead, a first choke circuit 63 and a second choke circuit 64 shown in FIG. 4D may be provided. The first choke circuit 63 includes an inductance element L1 and a resistance element R1.
And a capacitor C1 in parallel. The second choke circuit 64 is configured by a circuit in which a parallel circuit of a resistance element R2 and a capacitor C2 is connected in series to an inductance element L2.

The first choke circuits 33, 43, 53,
63 and second choke circuits 34, 44, 54, 64
Has a real part of impedance at high frequency,
It is possible to suppress a change in impedance when the power supply side is viewed from the amplifying element Tr1, thereby preventing impedance mismatching and oscillation.

In particular, the choke circuit 33 shown in FIG.
In No. 34, since no DC current flows through the resistors R1 and R2, there is no DC power consumption at the resistors R1 and R2.
On the other hand, the circuits 43, 44, and 5 shown in FIGS.
In 3, 54, 63, and 64, DC power consumption occurs in the resistors R1 and R2, but when the amplifying element is an FET and the gate is a signal input terminal, almost no gate current flows. Therefore, FIGS. 4 (B), (C), (D)
Even if the circuits 43, 53, and 63 are used, there is almost no DC power consumption. Further, even when the amplifying element is a bipolar transistor and the base is a signal input terminal, the base current may be smaller than the collector current by a factor of 1 due to the amplifying action of the transistor. Therefore, even if the circuits 43, 53, and 63 of FIGS. 4B, 4C, and 4D are used, there is almost no DC power consumption.

Further, when the power to be handled is weak, such as a receiving amplifier, the bias current supplied to the amplifying element is small, so that the DC power consumption by the resistors R1 and R2 is small, and FIG. B), (C), (D) choke circuit 43,
53, 63 and choke circuits 44, 54, 64 can be applied.

[0065]

As is apparent from the above description, in the power amplifier according to the first aspect of the present invention, a choke circuit including an inductance element L, a capacitance element C, and a resistance element R is connected between a bias supply power supply and an amplification element. . Therefore,
Even when the choke circuit resonates with the power supply impedance at a frequency at which the impedance of the choke circuit has an inductive or capacitive component, the resistance element R suppresses the Q value of the resonance to a low value. As a result, it is possible to suppress a variation in impedance when the bias supply power supply side including the choke circuit is viewed from the amplifying element, and it is possible to suppress occurrence of impedance mismatch and oscillation of the power amplifier.

According to a second aspect of the present invention, in the power amplifier according to the first aspect, the size of the power amplifier is reduced by using a field effect transistor or a bipolar transistor made of a silicon semiconductor or a compound semiconductor. I can do it.

According to a third aspect of the present invention, the choke circuit is constituted by a parallel circuit in which an inductance element, a capacitance element, and a resistance element are connected in parallel with each other.

According to the third aspect of the present invention, assuming that the inductance, capacitance, and resistance of the inductance element, the capacitance element, and the resistance element are L, C, and R, the impedance Zt of the parallel circuit is expressed as Re (Zt) = ( ωL) ² R / (R ² (1−ω ² LC) ² + (ωL) ² ) Im (Zt) = ωLR ² (1−ω ² LC) / (R ² (1−ω ² LC) ²
+ (ΩL) ² ), and a real part also exists at high frequencies.

Therefore, regardless of the value of the impedance on the power supply side, the impedance viewed from the amplifying element and the bias supply power supply side including the parallel circuit becomes a value not less than the real part Re (Zt) of the impedance Zt. Limited. Therefore, the impedance fluctuation when viewing the bias supply power supply side including the parallel circuit from the amplifying element is suppressed. Further, since the DC current supplied from the bias supply power supply to the amplification element flows through the inductance element L, no DC loss occurs due to the resistance element R. Further, as described above, the capacitance value of the capacitance element C connected in parallel with the inductance element L allows the inductance value of the inductance element L to be reduced and the size of the inductance element L to be reduced.

According to a fourth aspect of the present invention, in the power amplifier according to the first or second aspect, the choke circuit includes a series connection circuit in which the capacitance element and the resistance element are connected in series, and an inductance element in parallel. It is composed of a circuit connected to.

According to the fourth aspect of the present invention, since no DC current flows through the resistance element, DC power consumption at the resistance element is eliminated.

According to the invention of claim 5, the resonance frequency of the choke circuit at which the real part Re (Zt) of the impedance Zt of the choke circuit is maximized is set higher than the operating frequency of the power amplifier. Can be reduced in the inductance element or the capacitance element of the choke circuit as compared with the case where is resonated at the operating frequency. Therefore, according to the invention of claim 5, further downsizing can be achieved. In the non-resonant state, the possibility of resonating with the power source impedance at the operating frequency increases, but since the Q value is reduced by the resistance element, the impedance fluctuation due to the resonance is suppressed as compared with the conventional example.

According to a sixth aspect of the present invention, the resistance value R of the resistor element or the real part Re (Zt) of the impedance of the choke circuit is higher than the input impedance or output impedance of the amplifier element at the operating frequency of the power amplifier. Set.

Thus, power consumption by the resistance element can be suppressed, and the gain of the power amplifier can be improved. on the other hand,
Since the resistance value R of the resistance element is set to 100 times or less of the input impedance or output impedance of the amplification element, the real part Re (Zt) of the impedance Zt of the choke circuit rapidly decreases at a frequency other than the resonance frequency. And avoiding the influence of the impedance on the power supply side.

In the invention according to claim 7, the choke circuit is shared by two or more amplifying stages, so that the number of choke circuits can be reduced and the power amplifier can be downsized.

Further, according to the invention of claim 8, the choke circuit is formed on the same semiconductor substrate together with the amplifying element, so that the choke circuit and the amplifying element can be connected by a short wiring. The parasitic inductance of the wiring and the parasitic capacitance between the wiring and the ground can be reduced, and a small power amplifier with further less characteristic fluctuation can be realized.

As described above, according to the present invention, it is possible to provide a small-sized power amplifier with little characteristic fluctuation due to the impedance on the power supply side.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a power amplifier according to the present invention.

FIG. 2 is a block diagram illustrating a power amplifier according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the power amplifier of the present invention.

FIG. 4A is a diagram showing a first modification of the choke circuit in the first, second, and third embodiments.
(B) is a diagram showing a second modification of the choke circuit,
FIG. 4C is a diagram showing a third modification of the choke circuit, and FIG. 4D is a diagram showing a fourth modification of the choke circuit.

FIG. 5 is a block diagram of a conventional power amplifier.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input matching circuit, 2 ... Output matching circuit, 3 ... First choke circuit, 4 ... Second choke circuit, 7, 8, 19 ... Connection line, 15 ... Part of input matching circuit, 16 ... Output matching circuit Part, 17: Interstage matching circuit, 18: Part of interstage matching circuit, L1, L2, L3, Lm1, Lm2, Lm3: Inductance element, C1, C2, C3, Cm1, Cm2
Cm3: capacitance element, R1, R2: resistance element,
Tr1, Tr2 ... transistors.

Claims (8)

[Claims] 1. A choke circuit comprising an inductance element, a capacitance element, and a resistance element is connected between at least one of a signal input side or a signal output side of an amplification element and a bias supply power supply of the amplification element. Characteristic power amplifier. 2. The power amplifier according to claim 1, wherein the amplifying element is a field-effect transistor or a bipolar transistor, and is made of a silicon semiconductor or a compound semiconductor. 3. The power amplifier according to claim 1, wherein the choke circuit is configured by a parallel circuit in which the inductance element, the capacitance element, and the resistance element are connected in parallel with each other. Power amplifier. 4. The power amplifier according to claim 1, wherein the choke circuit is a circuit in which the capacitance element and the resistance element are connected in series, and a circuit in which an inductance element is connected in parallel. A power amplifier characterized by being constituted. 5. The power amplifier according to claim 1, wherein a resonance frequency of the choke circuit is set higher than an operation frequency of the amplification element. 6. The power amplifier according to claim 1, wherein, at a frequency at which the amplifying element operates, a resistance value of the resistance element or a real part of an impedance of the choke circuit is adjusted by the amplification. A power amplifier, wherein the input impedance or the output impedance is set higher than the element and the input impedance or the output impedance is set to a value of 100 times or less. 7. The power amplifier according to claim 1, wherein the power amplifier is a multi-stage power amplifier having a plurality of amplifying elements, wherein the choke circuit includes the inductance element, the capacitance element, and the resistance element. Is shared by two or more amplification stages. 8. The power amplifier according to claim 1, wherein the choke circuit is formed together with the amplifying element on the same semiconductor substrate.