WO2014087479A1 - High-frequency power amplifier - Google Patents

Abstract

The present invention is provided with a series resonant circuit (7), one end of which is connected between a high-frequency signal amplification transistor (3) and a bias circuit (6), and the other end of which is connected to ground, the series resonant circuit (7) including an inductor (8) and a capacitor (9). By this configuration, noise having a differential frequency that occurs in the bias circuit (6) is suppressed from being input to the high-frequency signal amplification transistor (3), the transmission band gain is thereby prevented from decreasing, and out-of-band noise can be suppressed.

Description

High frequency power amplifier

The present invention relates to a high frequency power amplifier applied to, for example, a broadband multiband power amplifier.

In recent years, mobile terminals are required to support a plurality of frequency bands.
Along with this, the number of high-frequency power amplifiers for transmission mounted is also increasing according to the number of frequency bands, and the occupation area of the high-frequency power amplifier in the mobile terminal tends to increase.
On the other hand, because of the increase in the number of parts associated with the increase in functionality and functionality of mobile terminals and the increase in battery size due to the increase in power consumption, downsizing of high-frequency amplifiers and multiple frequency bands with a single amplifier There is a need for multi-band processing.

As for a high frequency power amplifier for a portable terminal, like a high frequency power amplifier described in Patent Document 1 below, a transistor for high frequency signal amplification using a FET (Field Effect Transistor) or an HBT (Heterojunction Bipolar Transistor), a bias circuit, And a matching circuit.

JP-A-11-195932

In a high frequency power amplifier for a portable terminal, there is a regulation for a reception band noise level at the time of transmission.
As mobile terminals become more multifunctional, they are required to have low noise levels in multiple frequency bands such as DTV (Digital Television) band, GPS (Global Positioning System) band, and ISM (Industrial Scientific Medical) band in addition to the reception band. It has been.

Generally, the out-of-band noise level output from the high-frequency power amplifier is represented by input noise level × out-of-band gain + nonlinear noise level.

If the transmission band, reception band, and other frequency bands are far enough to change the gain in each band independently, it is possible to reduce the out-of-band noise level by reducing the out-of-band gain. .
However, when the reception band is close to the transmission band, when other frequency bands are close to the transmission band, or by realizing wideband frequency characteristics, multiple frequency bands can be amplified by a common high-frequency signal amplification transistor. In a band power amplifier, when there are reception bands or other frequency bands between multiple transmission bands, the out-of-band noise level is lowered by reducing only the out-of-band gain without reducing the transmission band gain. It is difficult to do.

On the other hand, regarding the non-linear noise level, focusing on the bias circuit, which is one of the noise generation sources, the bias circuit generates noise having frequency components in the reception band and other bands, as well as in the transmission band, reception band, and other areas. Noise having a difference frequency (difference frequency) from the frequency band is generated.
When noise having a difference frequency is input from the bias circuit to the high frequency signal amplification transistor, the transmission wave signal and the noise having the difference frequency are mixed in the high frequency signal amplification transistor, and are out of band in the reception band and other frequency bands. There were problems such as noise.

The present invention has been made in order to solve the above-described problems. By suppressing the noise having the difference frequency generated in the bias circuit from being input to the high frequency signal amplifying transistor, the transmission band gain is increased. An object of the present invention is to obtain a high-frequency power amplifier that suppresses out-of-band noise without reducing it.

A high-frequency power amplifier according to the present invention includes a high-frequency signal amplification transistor that amplifies a high-frequency signal, a bias circuit that supplies a bias to a high-frequency signal input side of the high-frequency signal amplification transistor, a high-frequency signal amplification transistor, and a bias circuit. One end is connected between the other end, the other end is grounded, and a series resonant circuit including an inductor and a capacitor is provided.

According to the present invention, the series resonance circuit including the inductor and the capacitor is provided, with one end connected between the high frequency signal amplifying transistor and the bias circuit and the other end grounded.
Therefore, by suppressing the noise having the difference frequency generated in the bias circuit from being input to the high frequency signal amplifying transistor, it is possible to suppress the out-of-band noise without reducing the transmission band gain. .

1 is a configuration diagram illustrating a high frequency power amplifier according to a first embodiment of the present invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 2 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 3 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 4 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 5 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 6 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 7 of this invention. It is a block diagram which shows the high frequency power amplifier by Embodiment 8 of this invention.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 1 of the present invention.
In the first embodiment, the input matching circuit 2 connected to the input terminal 1 and one or more stages connected to the subsequent stage of the input matching circuit 2 for amplifying a high frequency signal from the input terminal 1 via the input matching circuit 2 A high frequency signal amplifying transistor 3 and an output matching circuit 4 connected to the subsequent stage of the high frequency signal amplifying transistor 3 and outputting the amplified high frequency signal to the output terminal 5 are provided.

A bias circuit 6 that supplies a bias to the high-frequency signal input side of the high-frequency signal amplifying transistor 3 and one end connected between the high-frequency signal amplifying transistor 3 and the bias circuit 6 and the other end connected to the ground. And a series resonance circuit 7 including a series connection of an inductor 8 and a capacitor 9.

When the high frequency signal amplifying transistor 3 is composed of an FET, a bias voltage is applied from the bias circuit 6 to the gate of the FET. When the high frequency signal amplifying transistor 3 is composed of an HBT, the bias circuit 6 A bias current is supplied to the base of the HBT.
The inductor 8 constituting the series resonance circuit 7 is formed by a spiral inductor or a chip inductor, and the capacitor 9 is formed by an MIM (Metal Insulator Metal) capacitor or a chip capacitor.

In the first embodiment, the values of the inductor 8 and the capacitor 9 are set so that the resonance frequency of the series resonance circuit 7 is in the vicinity of the difference frequency, thereby reducing the impedance of the series resonance circuit 7 at the difference frequency.
As a result, the noise having the difference frequency is caused to flow to the ground via the series resonance circuit 7, thereby suppressing the noise having the difference frequency from being input to the high frequency signal amplifying transistor 3.

Further, when the inductance of the inductor 8 is L [H], the input impedance of the high frequency signal amplification transistor 3 is Rintr [Ω], and the frequency of the transmission band is fRF [Hz], L> 5 × Rintr / 2π · fRF. L is set so that the following relationship holds, and the impedance of the series resonant circuit 7 is set sufficiently high with respect to the input impedance of the high-frequency signal amplifying transistor 3, so that the signal in the transmission band is grounded via the series resonant circuit 7. Suppresses the flow to

As described above, the out-of-band noise level can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain.

In the case of a multistage amplifier including two or more stages of high-frequency signal amplifying transistors 3, any one or all of the amplifying stage bias circuits 6 are connected in series between the high-frequency signal amplifying transistors 3. A resonance circuit 7 may be connected.
In particular, the noise generated in the first-stage high-frequency signal amplifying transistor 3 is amplified in the subsequent stage, and thus has a great influence on the output out-of-band noise.
Therefore, the effect of reducing the out-of-band noise level obtained when the series resonance circuit 7 is connected to the first stage is great, and the number of series resonance circuits 7 to be connected can be reduced, so that the size can be reduced.
On the other hand, in the final stage, since it is used with an output with a small back-off in order to achieve high efficiency, distortion becomes large and out-of-band noise due to mixing tends to occur.
Therefore, the effect of reducing the out-of-band noise level obtained when the series resonance circuit 7 is connected to the final stage is great, and the number of series resonance circuits 7 to be connected can be reduced, so that the size can be reduced.

Further, by using a spiral inductor for the inductor 8, it is possible to reduce the size.
On the other hand, the use of a chip inductor results in a low loss, so that an effect of suppressing a decrease in transmission band gain can be obtained.
The capacitor 9 can be miniaturized by using an MIM capacitor when the required capacitance value is small.
On the other hand, since a large capacitance can be realized by using a chip capacitor, it is possible to cope with a case where the difference frequency is low.

As described above, according to the first embodiment, one end is connected between the high-frequency signal amplifying transistor 3 and the bias circuit 6 and the other end is connected to the ground, and includes the inductor 8 and the capacitor 9 in series. A resonance circuit 7 was provided.
Therefore, by suppressing the noise having the difference frequency generated in the bias circuit 6 from being input to the high frequency signal amplification transistor 3, the out-of-band noise can be suppressed without reducing the transmission band gain.

Further, according to the first embodiment, the inductance of the inductor 8 is L [H], the frequency of the high-frequency signal amplified by the high-frequency signal amplification transistor 3 is fRF [Hz], and the input impedance of the high-frequency signal amplification transistor 3 Is set to Rintr [Ω] so that the relationship of L> 5 × Rintr / 2π · fRF is established.
Therefore, by setting the impedance of the series resonance circuit 7 sufficiently high with respect to the input impedance of the high frequency signal amplification transistor 3, it is possible to suppress the transmission band signal from flowing to the ground via the series resonance circuit 7. .

Furthermore, according to the first embodiment, the high-frequency signal amplification transistor 3 is a multistage amplifier having two or more stages, and the series resonance circuit 7 includes the first-stage high-frequency signal amplification transistor 3 and the bias circuit 6. One end was connected between.
Therefore, the effect of reducing the out-of-band noise level obtained when the series resonance circuit 7 is connected to the first stage is great, and the number of series resonance circuits 7 to be connected can be reduced, so that the size can be reduced. it can.

Further, according to the first embodiment, the inductor 8 of the series resonant circuit 7 is provided with a spiral inductor.
Therefore, it is possible to reduce the size.

Furthermore, according to the first embodiment, the inductor 8 of the series resonant circuit 7 is provided as a chip inductor.
Therefore, since the loss is low, it is possible to suppress a decrease in transmission band gain.

Furthermore, according to the first embodiment, the capacitor 9 of the series resonant circuit 7 is provided as a MIM capacitor.
Therefore, it is possible to reduce the size.

Furthermore, according to the first embodiment, the capacitor 9 of the series resonance circuit 7 is provided as a chip capacitor.
Therefore, since a large capacitance can be realized, it is possible to cope with a case where the difference frequency is low.

Embodiment 2. FIG.
FIG. 2 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 2 of the present invention.
In the series resonant circuit 10 of the second embodiment, a plurality of series resonant circuits 7 of the high-frequency power amplifier according to the first embodiment are connected in parallel, and the inductor 8 and the capacitor 9 constituting each series resonant circuit 7 have different values. Is set to have a plurality of different resonance frequencies.

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In this case, the second embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands with respect to a plurality of transmission band frequencies.

The second embodiment is different from the first embodiment only in the series resonance circuit 10 connected. In addition to the effects obtained in the first embodiment, the series resonance circuit 10 connected in parallel further transmits. By having resonance frequencies at a plurality of difference frequencies between a band frequency and a plurality of out-of-band frequencies, noise having a plurality of difference frequencies generated by the bias circuit 6 is grounded via a plurality of series resonance circuits 10. The input to the high frequency signal amplification transistor 3 is suppressed.

Similarly to the first embodiment, the inductance of each inductor 8 is set so that the impedance of the series resonant circuit 10 is sufficiently higher than the input impedance of the high-frequency amplification transistor 3. The signal is prevented from flowing to the ground via the series resonant circuit 10.

As described above, the out-of-band noise level in a plurality of frequency bands can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain. Is possible.

As described above, according to the second embodiment, a plurality of series resonant circuits 10 are connected in parallel, each having a different resonant frequency.
Therefore, the series resonance circuit 10 connected in parallel has a plurality of difference frequencies generated by the bias circuit 6 by having resonance frequencies at a plurality of difference frequencies between the transmission band frequency and the plurality of out-of-band frequencies. Noise can be caused to flow through the plurality of series resonance circuits 10 to the ground, and input to the high frequency signal amplifying transistor 3 can be suppressed.

Embodiment 3 FIG.
FIG. 3 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 3 of the present invention.
The series resonant circuit 11 of the third embodiment includes a plurality of capacitors 9 connected in parallel via switches 12 instead of the capacitors 9 constituting the series resonant circuit 7 of the high frequency power amplifier according to the first embodiment. The resonance frequency is made variable by switching the number or size of the capacitors 9 by turning on / off the switch 12.

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In this case, the third embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands with respect to a plurality of transmission band frequencies.

The third embodiment is different from the first embodiment only in the series resonant circuit 11 that is connected. In addition to the effects obtained in the first embodiment, the frequency band outside the band where the noise level is desired to be further reduced. By switching the value of the capacitor 9 of the series resonance circuit 11 according to the above, noise having a plurality of difference frequencies generated in the bias circuit 6 is caused to flow to the ground via the series resonance circuit 11, and is supplied to the high frequency signal amplifying transistor 3. Suppress input.

Similarly to the first embodiment, the inductance of the inductor 8 is set so that the impedance of the series resonant circuit 11 is sufficiently higher than the input impedance of the high-frequency signal amplification transistor 3, so that the signal in the transmission band is set. Is prevented from flowing to the ground via the series resonant circuit 11.

As described above, by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain, the out-of-band noise level according to the frequency band in which the noise is desired to be reduced. Can be reduced.
In addition, the third embodiment can be downsized because the inductor 8 having a large size is shared with the second embodiment and can be realized by the small switch 12.

As described above, according to the third embodiment, a plurality of capacitors 9 of the series resonant circuit 11 are connected in parallel via the switch 12, and the capacitor 9 is switched by turning on / off the switch 12. A circuit in which the resonance frequency of the series resonance circuit 11 is changed is provided.
Therefore, by switching the value of the capacitor 9 of the series resonance circuit 11 according to the frequency band outside the band where the noise level is desired to be reduced, the noise having a plurality of difference frequencies generated in the bias circuit 6 is passed through the series resonance circuit 11. It is possible to suppress the input to the high-frequency signal amplification transistor 3 by flowing to the ground.

Embodiment 4 FIG.
FIG. 4 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 4 of the present invention.
In the fourth embodiment, instead of the series resonant circuit 7 of the high frequency power amplifier according to the first embodiment, the high frequency signal amplifying transistor 3 and the bias circuit 6 are connected in series, and the inductor 14 and the capacitor 15 are connected in parallel. A parallel resonant circuit 13 is provided.

The inductor 14 constituting the parallel resonance circuit 13 is formed by a spiral inductor or a chip inductor, and the capacitor 15 is formed by an MIM capacitor or a chip capacitor.

In the fourth embodiment, the values of the inductor 14 and the capacitor 15 are set so that the resonance frequency of the parallel resonance circuit 13 is in the vicinity of the difference frequency, thereby increasing the impedance of the parallel resonance circuit 13 at the difference frequency.
As a result, noise having a difference frequency is prevented from being input to the high frequency signal amplification transistor 3.

As described above, the out-of-band noise level can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain.

In the case of a multi-stage amplifier including two or more stages of high-frequency signal amplification transistors 3, a parallel connection between the bias circuit 6 of any amplification stage or all amplification stages and the high-frequency signal amplification transistors 3 is performed. A resonance circuit 13 may be connected.
In particular, the noise generated in the first-stage high-frequency signal amplifying transistor 3 is amplified in the subsequent stage, and thus has a great influence on the output out-of-band noise.
Therefore, the effect of reducing the out-of-band noise level obtained when the parallel resonance circuit 13 is connected to the first stage is great, and the number of parallel resonance circuits 13 to be connected can be reduced, and the size can be reduced.
On the other hand, in the final stage, since it is used with an output with a small back-off in order to realize high efficiency, distortion becomes large and out-of-band noise due to mixing tends to occur.
Therefore, the effect of reducing the out-of-band noise level obtained when the parallel resonance circuit 13 is connected to the final stage is great, and the number of parallel resonance circuits 13 to be connected can be reduced, and the size can be reduced.

Further, the use of a spiral inductor for the inductor 14 enables miniaturization.
On the other hand, since the loss is reduced by using the chip inductor, an effect of suppressing the decrease in the transmission band gain can be obtained.
The capacitor 15 can be miniaturized by using an MIM capacitor when the required capacitance value is small.
On the other hand, since a large capacitance can be realized by using a chip capacitor, it is possible to cope with a case where the difference frequency is low.

As described above, according to the fourth embodiment, the parallel resonant circuit 13 including the inductor 14 and the capacitor 15 is provided in series between the high-frequency signal amplification transistor 3 and the bias circuit 6.
Therefore, by suppressing the noise having the difference frequency generated in the bias circuit 6 from being input to the high frequency signal amplification transistor 3, the out-of-band noise can be suppressed without reducing the transmission band gain.

Further, according to the fourth embodiment, the high-frequency signal amplification transistor 3 is a multistage amplifier having two or more stages, and the parallel resonance circuit 13 includes the first-stage high-frequency signal amplification transistor 3 and the bias circuit 6. The one connected in series was provided.
Therefore, the effect of reducing the out-of-band noise level obtained when the parallel resonant circuit 13 is connected to the first stage is great, and the number of parallel resonant circuits 13 to be connected can be reduced, thereby enabling downsizing. it can.

Embodiment 5 FIG.
FIG. 5 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 5 of the present invention.
In the fifth embodiment, a plurality of parallel resonant circuits 13 of the high-frequency power amplifier according to the fourth embodiment are connected in series, and different values are set for the inductor 14 and the capacitor 15 constituting each parallel resonant circuit. Each has a plurality of different resonance frequencies.

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In such a case, the fifth embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands with respect to a plurality of transmission band frequencies.

The fifth embodiment is different from the fourth embodiment only in the parallel resonance circuit 16 connected. In addition to the effects obtained in the fourth embodiment, the parallel resonance circuit 16 connected in series further transmits. The impedance of the parallel resonant circuit 16 at a plurality of difference frequencies is increased by having resonance frequencies at a plurality of difference frequencies between the band frequency and the plurality of out-of-band frequencies.
As a result, the noise having a plurality of difference frequencies generated in the bias circuit 6 is suppressed from being input to the high frequency signal amplification transistor 3.

As described above, the out-of-band noise level in a plurality of frequency bands can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain. Is possible.

As described above, according to the fifth embodiment, a plurality of parallel resonant circuits 16 are connected in series, each having a different resonant frequency.
Therefore, the parallel resonance circuit 16 connected in series has resonance frequencies at a plurality of difference frequencies between the transmission band frequency and the plurality of out-of-band frequencies, thereby reducing the impedance of the parallel resonance circuit 16 at the plurality of difference frequencies. Make it high.
Thereby, it is possible to suppress the noise having a plurality of difference frequencies generated in the bias circuit 6 from being input to the high frequency signal amplification transistor 3.

Embodiment 6 FIG.
FIG. 6 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 6 of the present invention.
In the sixth embodiment, instead of the capacitor 15 constituting the parallel resonant circuit 13 of the high-frequency power amplifier according to the fourth embodiment, a plurality of capacitors 15 each connected in parallel via a switch 18 are provided. The resonance frequency is made variable by switching the number or size of the capacitors 15 by turning on / off.

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In this case, the sixth embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands with respect to a plurality of transmission band frequencies.

The sixth embodiment is different from the fourth embodiment only in the parallel resonant circuit 17 connected. In addition to the effects obtained in the fourth embodiment, the frequency band outside the band where the noise level is desired to be further reduced. By switching the value of the capacitor 15 of the parallel resonance circuit 17 according to the above, the impedance of the parallel resonance circuit 17 is increased for a plurality of frequency bands.
As a result, the noise having a plurality of difference frequencies generated in the bias circuit 6 is suppressed from being input to the high frequency signal amplification transistor 3.

As described above, by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high frequency signal amplification transistor 3 without reducing the transmission band gain, the out-of-band noise level can be set for each frequency band in which noise is desired to be reduced. It becomes possible to reduce.
Further, the sixth embodiment can be miniaturized because the inductor 14 having a large size is shared with the fifth embodiment and can be realized by the small switch 18.

As described above, according to the sixth embodiment, a plurality of capacitors 15 of the parallel resonant circuit 17 are connected in parallel via the switch 18, and the capacitor 15 is switched by turning on / off the switch 18. The parallel resonance circuit 17 is provided with a variable resonance frequency.
Therefore, by switching the value of the capacitor of the parallel resonant circuit 17 according to the frequency band outside the band where the noise level is desired to be reduced, noise having a plurality of difference frequencies generated in the bias circuit 6 is input to the high frequency signal amplifying transistor 3. Can be suppressed.

Embodiment 7 FIG.
FIG. 7 shows a configuration diagram of a high-frequency power amplifier according to Embodiment 7 of the present invention.
The series resonant circuit 19 of the seventh embodiment is obtained by connecting a resistor 20 in series to the series resonant circuit 7 of the high-frequency power amplifier according to the first embodiment. The impedance of the series resonant circuit 19 is set to a wider frequency band. It is a low one.

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In this case, the seventh embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands in a plurality of transmission band frequencies.

The seventh embodiment is different from the first embodiment only in the series resonance circuit 19 that is connected. In addition to the effects obtained in the first embodiment, the resonance of the series resonance circuit 19 including the resistor 20 is further obtained. By setting the values of the inductor 8 and the capacitor 9 so that the frequency becomes an intermediate frequency between the plurality of difference frequencies close to the frequency, the impedance of the series resonance circuit 19 at the plurality of difference frequencies is lowered.
Thus, noise having a plurality of difference frequencies is caused to flow to the ground via the series resonance circuit 19, thereby suppressing the noise having the plurality of difference frequencies from being input to the high frequency signal amplification transistor 3.

Similarly to the first embodiment, by setting the inductance of the inductor 8 so that the impedance of the series resonance circuit 19 is sufficiently higher than the input impedance of the high frequency amplification transistor 3, the signal in the transmission band can be obtained. The flow to the ground via the series resonance circuit 19 is suppressed.

As described above, the out-of-band noise level in a plurality of frequency bands can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain. Is possible.
In addition, the seventh embodiment can be downsized because a plurality of inductors 8 and capacitors 9 can be used in common with the second and third embodiments.

As described above, according to the seventh embodiment, the series resonance circuit 19 includes the inductor 8 and the capacitor 9 including the resistor 20 connected in series.
Therefore, by setting the values of the inductor 8 and the capacitor 9 so that the resonance frequency of the series resonance circuit 19 including the resistor 20 becomes an intermediate frequency between the plurality of difference frequencies close to each other, the series resonance circuit at the plurality of difference frequencies. 19 Impedance is lowered.
Thereby, it is possible to suppress the noise having a plurality of difference frequencies generated in the bias circuit 6 from being input to the high-frequency signal amplification transistor 3 by flowing to the ground via the series resonance circuit 19.

Embodiment 8 FIG.
FIG. 8 shows a configuration diagram of a high-frequency power amplifier according to an eighth embodiment of the present invention.
In the eighth embodiment, a resistor 22 is connected in series to the parallel resonant circuit 13 of the high-frequency power amplifier according to the fourth embodiment, and the impedance of the parallel resonant circuit 21 is increased over a wider frequency band. .

There may be a case where there are a plurality of difference frequencies between the transmission band, the reception band, and other frequency bands, or the difference frequency may differ depending on the transmission band frequency.
In this case, the eighth embodiment reduces out-of-band noise in a plurality of reception bands and other frequency bands in a plurality of transmission band frequencies.

The eighth embodiment is different from the fourth embodiment only in the connected parallel resonance circuit 21. In addition to the effects obtained in the fourth embodiment, the resonance of the parallel resonance circuit 21 including the resistor 22 is further obtained. By setting the values of the inductor 14 and the capacitor 15 so that the frequency becomes an intermediate frequency of the plurality of difference frequencies close to the frequency, the impedance of the parallel resonant circuit 21 at the plurality of difference frequencies is increased.
As a result, the noise having a plurality of difference frequencies generated in the bias circuit 6 is suppressed from being input to the high frequency signal amplification transistor 3.

As described above, the out-of-band noise level in a plurality of frequency bands can be reduced by suppressing the input of noise having a difference frequency from the bias circuit 6 to the high-frequency signal amplification transistor 3 without reducing the transmission band gain. Is possible.
Further, in the eighth embodiment, since the plurality of inductors 14 and the capacitors 15 can be made common to the fifth and sixth embodiments, the size can be reduced.

As described above, according to the eighth embodiment, the parallel resonant circuit 21 includes the inductor 14 and the capacitor 15 including the resistor 22 connected in series.
Therefore, by setting the values of the inductor 14 and the capacitor 15 so that the resonance frequency of the parallel resonance circuit 21 including the resistor 22 becomes an intermediate frequency of the plurality of difference frequencies close to each other, the parallel resonance circuit at the plurality of difference frequencies Increase the impedance of 21.
Thereby, it is possible to suppress the noise having a plurality of difference frequencies generated in the bias circuit 6 from being input to the high frequency signal amplification transistor 3.

The high-frequency power amplifiers shown in the first to eighth embodiments can be applied to a wideband multiband power amplifier that includes a reception band between a plurality of transmission bands for power amplification.

In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

As described above, in the high frequency power amplifier according to the present invention, one end is connected between the high frequency signal amplifying transistor 3 and the bias circuit 6 and the other end is connected to the ground, and the series resonance including the inductor 8 and the capacitor 9 is performed. Since the circuit 7 is provided, it is suitable for use in a wideband multiband power amplifier.

1 input terminal, 2 input matching circuit, 3 high frequency signal amplification transistor, 4 output matching circuit, 5 output terminal, 6 bias circuit, 7, 10, 11, 19 series resonance circuit, 8, 14 inductor, 9, 15 capacitor, 12, 18 switch, 13, 16, 17, 21 parallel resonant circuit, 20, 22 resistance.

Claims (19)

A high frequency signal amplification transistor for amplifying the high frequency signal;
A bias circuit for supplying a bias to the high-frequency signal input side of the high-frequency signal amplification transistor;
A series resonant circuit including one end connected between the high frequency signal amplification transistor and the bias circuit and the other end grounded, including an inductor and a capacitor,
High frequency power amplifier with The series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein a plurality of the high frequency power amplifiers are connected in parallel, and each has a different resonance frequency. The capacitor of the series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein a plurality of each are connected in parallel via a switch. 4. The high-frequency power amplifier according to claim 3, wherein the capacitor is switched by turning on / off the switch to change a resonance frequency of the series resonance circuit. The inductance of the inductor is L [H],
The frequency of the high frequency signal amplified by the high frequency signal amplifying transistor is fRF [Hz],
When the input impedance of the high frequency signal amplification transistor is Rintr [Ω],
L> 5 × Rintr / 2π · fRF
The high-frequency power amplifier according to claim 1, wherein The series resonant circuit is:
The high-frequency power amplifier according to claim 1, wherein the inductor and the capacitor include a resistor connected in series. A high frequency signal amplification transistor for amplifying the high frequency signal;
A bias circuit for supplying a bias to the high-frequency signal input side of the high-frequency signal amplification transistor;
A parallel resonant circuit connected in series between the high-frequency signal amplification transistor and the bias circuit, and including an inductor and a capacitor;
High frequency power amplifier with The parallel resonant circuit is:
8. The high-frequency power amplifier according to claim 7, wherein a plurality of the high-frequency power amplifiers are connected in series, each having a different resonance frequency. The capacitor of the parallel resonant circuit is:
8. The high frequency power amplifier according to claim 7, wherein a plurality of each are connected in parallel via a switch. 10. The high frequency power amplifier according to claim 9, wherein the capacitor is switched by turning on / off the switch to change a resonance frequency of the parallel resonance circuit. The parallel resonant circuit is:
8. The high frequency power amplifier according to claim 7, further comprising a resistor connected in series with the inductor and the capacitor. The high-frequency signal amplification transistor includes:
A multistage amplifier consisting of two or more stages,
The series resonant circuit is:
The high-frequency power amplifier according to claim 1, wherein one end is connected between the first-stage high-frequency signal amplification transistor and the bias circuit. The high-frequency signal amplification transistor includes:
A multistage amplifier consisting of two or more stages,
The parallel resonant circuit is:
The high-frequency power amplifier according to claim 7, wherein the first-stage high-frequency signal amplification transistor and the bias circuit are connected in series. 2. The high frequency power amplifier according to claim 1, wherein the power amplifier is a wideband multiband power amplifier including a reception band between a plurality of transmission bands for power amplification. The high-frequency power amplifier according to claim 7, wherein the high-frequency power amplifier is a wideband multiband power amplifier including a reception band between a plurality of transmission bands for power amplification. The inductor of the series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein the high frequency power amplifier is a spiral inductor. The inductor of the series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein the high frequency power amplifier is a chip inductor. The capacitor of the series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein the high frequency power amplifier is an MIM capacitor. The capacitor of the series resonant circuit is:
2. The high frequency power amplifier according to claim 1, wherein the high frequency power amplifier is a chip capacitor.

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