JP2010135941A - High frequency power amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency power amplifier, capable of further improving the efficiency of a Doherty power amplifier. <P>SOLUTION: In the Doherty power amplifier provided with a higher harmonic reflection circuit 64 in a carrier amplifier circuit 6, an input stage of the Doherty power amplifier is provided with a harmonic wave generating circuit 3 for generating a secondary harmonic wave for injecting the secondary harmonic waves to the carrier amplifier circuit 6. The harmonic wave generating circuit 3 includes a saturation type secondary harmonic wave generator 37, a variable attenuator 34, and a variable phase shifter 33 for saturating the output level of the secondary harmonic waves at a necessary and sufficient level and further adjust it so that it reaches an optimal level, the efficiency due to harmonic wave reflection is improved, and power consumption in the harmonic wave generation circuit 3 is reduced. Thus, the high-frequency power amplifier capable of further improving the efficiency of the Doherty amplifier as a whole can be provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-frequency power amplifier that amplifies a high-frequency signal, and more particularly to a high-frequency power amplifier that can improve power conversion efficiency.

[Description of Prior Art]
The transmission power amplifier amplifies a high-frequency signal to a required transmission output, and is the part that consumes the most power in most radio devices.
The power consumed by the power amplifier is not only converted into a high-frequency output but also released as heat that causes internal loss.
Therefore, in order to reduce the amount of heat generation and reduce power consumption and improve reliability, it is required to increase the power conversion efficiency of the power amplifier to suppress useless internal loss.
In order to meet this demand, there are amplifiers incorporating various high-efficiency operation methods, for example, class F amplifiers.

[Conventional class F amplifier]
A conventional class F amplifier will be briefly described.
The class F amplifier has a harmonic reflection circuit connected to the drain terminal of the FET which is an active element, and the output impedance viewed from the device is short-circuited with respect to the even-order harmonic frequency, the fundamental frequency and the odd-order harmonic frequency. By keeping the circuit open, the FET drain voltage and drain current waveforms do not overlap.

As a result, the operation of the FET is that the drain voltage becomes zero when the drain current is flowing, and conversely the drain current becomes zero when the drain voltage is applied. The power can always be zero.
That is, ideally, the power consumption in the FET can be reduced to zero and the internal loss can be suppressed, assuming that the time waveforms of the FET drain voltage and drain current do not overlap.

  Further, contrary to the above-described class F amplifier, there is an amplifier that can obtain a waveform that is matched at the fundamental frequency, opened at the even-order harmonic frequency, and short-circuited at the odd-order harmonic frequency. In such an amplifier, the harmonic reflection circuit reflects even-order harmonics. Also in this case, the drain voltage becomes zero when the drain current is flowing, and conversely, the drain current becomes zero when the drain voltage is applied. It can always be zero.

[Doherty amplifier provided with Doherty amplifier and harmonic reflection circuit: FIG. 6]
As a conventional amplifier for achieving high efficiency, there is a Doherty amplifier.
Furthermore, it is a well-known technique to achieve higher efficiency by using a harmonic reflection circuit in the Doherty amplifier.
A configuration of a Doherty amplifier including a conventional harmonic reflection circuit will be described with reference to FIG. FIG. 6 is a block diagram showing the configuration of a Doherty amplifier having a conventional harmonic reflection circuit.
As shown in FIG. 6, a conventional Doherty amplifier including a harmonic reflection circuit includes an input terminal 1, an output terminal 2, a distributor 4, a phase shifter 5, a carrier amplifier circuit 6, and a peak amplifier circuit. 7, a transmission line 8, a synthesis point 9, and a transmission line 10.

  Further, the carrier amplifier circuit 6 includes an input matching circuit 61, an FET 62, an output matching circuit 63, and a harmonic reflection circuit 64. The peak amplifier circuit 7 includes an input matching circuit 71, an FET 72, and an output matching circuit. The circuit 73 and the harmonic reflection circuit 74 are comprised. In some cases, the harmonic reflection circuit is provided only in the carrier amplifier circuit.

  The signal input from the input terminal 1 is distributed by the distributor 4, one of which is input to the carrier amplifier circuit 6, amplified by the FET 62, and impedance-converted by the transmission line 8 via the output matching circuit 63. The The harmonic reflection circuit 64 reflects the harmonic generated by the FET 62 and improves the efficiency of the carrier amplification circuit 6.

  The other signal distributed by the distributor 4 is adjusted by the phase shifter 5 in accordance with the phase of the carrier amplifier circuit 6, then input to the peak amplifier circuit 7, amplified by the FET 72, and output by the output matching circuit 73. Impedance converted and output. The harmonic reflection circuit 74 reflects the harmonic generated by the FET 72 and improves the efficiency of the peak amplification circuit 7.

  At the synthesis point 9, the output from the transmission line 8 and the output from the peak amplifier circuit 7 are synthesized, and further impedance-transformed to match an output load (not shown) in the transmission line 10 and outputted from the output terminal 2. Connected to the load.

The general Doherty amplifier configuration is obtained by removing the harmonic reflection circuits 64 and 74 from the configuration of FIG.
Here, the efficiency of the Doherty amplifier will be briefly described.
The FET 62 of the carrier amplifier circuit 6 is biased to class AB, and the FET 72 of the peak amplifier circuit 7 is biased to class B or class C. For this reason, the FET 62 operates alone while the input level is low and the FET 72 does not operate. When the FET 62 enters the saturation region, that is, when the linearity of the FET 62 starts to break down, the FET 72 starts to operate, the output of the FET 72 is supplied to the load, and the load is driven together with the FET 62. Thereby, in the Doherty amplifier, even when the output level is lower than the maximum output level, high efficiency can be obtained.
In the configuration of FIG. 6, since the carrier amplifier circuit 6 and the peak amplifier circuit 7 are provided with the harmonic reflection circuit, the efficiency can be further improved.

[Prior art documents]
As a prior art related to an amplifier that achieves high efficiency, there is JP-A-2005-204208 (Patent Document 1).
Patent Document 1 generates an odd-order harmonic signal for a fundamental wave signal to be amplified, combines the odd-order harmonic signal with the fundamental wave signal to be amplified to generate a rectangular wave signal, When the rectangular wave signal is amplified by an active element and the load side is viewed from the output end of the active element, the impedance value for the odd-order harmonic signal is infinite, and the impedance for the even-order harmonic signal is An amplifier that can achieve high efficiency by setting the value to zero is described.

JP-A-2005-204208

  However, even in an amplifier in which a harmonic reflection circuit is combined with a conventional Doherty amplifier, there is a problem that when the output level is low, the output level of the harmonic is lowered, and the effect of improving the efficiency is reduced.

  In addition, although the said patent document 1 describes injecting odd-order harmonics into the amplifier input, it does not describe injecting even-order high-frequency waves.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-frequency power amplifier that can obtain higher efficiency than a Doherty amplifier combined with a conventional harmonic reflection circuit.

  The present invention for solving the problems of the above conventional example is a carrier amplifier circuit having a first amplifier element operating in class AB and a peak amplifier circuit having a second amplifier element operating in class B or class C. A high frequency power amplifier having a Doherty amplifier that synthesizes and outputs the outputs of the carrier amplifier circuit and the peak amplifier circuit, the carrier amplifier circuit having a second harmonic frequency output from the first amplifier element. A first harmonic reflection circuit for reflecting is provided, and a second harmonic of a fundamental frequency that saturates at a specific level is synthesized with an input signal of a fundamental frequency that is input to the carrier amplification circuit. It is characterized by inputting.

  In the high frequency power amplifier according to the present invention, the peak amplification circuit includes a second harmonic reflection circuit that reflects the second harmonic frequency output from the second amplification element, and is input to the peak amplification circuit. The second harmonic of the fundamental frequency saturated at a specific level is synthesized with the input signal of the fundamental frequency to be input to the peak amplifier circuit.

  According to the present invention, the carrier amplification circuit includes the first harmonic reflection circuit that reflects the second harmonic frequency output from the first amplification element, and the fundamental frequency input to the carrier amplification circuit is input. Since the signal is a high-frequency amplifier that synthesizes the second harmonic of the fundamental frequency saturated at a specific level and inputs it to the carrier amplifier circuit, the second harmonic injection and the second harmonic reflection are performed in the carrier amplifier circuit. The efficiency of the Doherty amplifier as a whole is improved by reducing the power consumption of the harmonic generator by reducing the power consumption of the harmonic generator by making the harmonic generator saturated and not outputting more than necessary second harmonics. There is an effect that can.

  Further, according to the present invention, the peak amplification circuit includes the second harmonic reflection circuit that reflects the second harmonic frequency output from the second amplification element, and the fundamental frequency input to the peak amplification circuit. Since the above high-frequency power amplifier that synthesizes the second harmonic of the fundamental frequency that saturates at a specific level with the input signal and inputs it to the peak amplifier circuit, the peak amplifier circuit also uses harmonic injection and harmonic reflection. The efficiency can be improved and the overall efficiency of the Doherty amplifier can be further improved.

[Summary of Invention]
Embodiments of the present invention will be described with reference to the drawings.
In the Doherty amplifier, the high frequency power amplifier according to the embodiment of the present invention includes a harmonic generator that generates a second harmonic before the distributor that distributes an input signal to a carrier amplifier and a peak amplifier, and the secondary generator. A vector adjuster that adjusts the phase and amplitude of the harmonic, and synthesizes the vector-adjusted harmonic into the input signal of the carrier amplifier and the peak amplifier, thereby generating the harmonic output of the Doherty amplifier with the harmonic reflection circuit. The level can be increased, and accordingly, the harmonic reflection level of the output can be increased to improve the efficiency.

  The high-frequency power amplifier according to the embodiment of the present invention is the above-described Doherty amplifier including a harmonic generation circuit, wherein the harmonic generator of the harmonic generation circuit is a saturated type, and the output level of the harmonic is necessary and sufficient. The efficiency can be further improved by reducing the power consumption of the harmonic generator to a level.

  In addition, the high-frequency power amplifier according to the embodiment of the present invention includes a first harmonic reflection circuit that reflects the second harmonic frequency output from the first amplification element in the carrier amplification circuit, and the Doherty amplifier A first distributor that distributes an input signal having a fundamental frequency to an input stage, and a second harmonic that has an output characteristic that saturates at a specific level from one of the fundamental signals distributed by the first distributor. A saturation harmonic generator for generating the second harmonic, a regulator for adjusting the phase and amplitude of the second harmonic generated by the saturation harmonic generator, a second harmonic having the phase and amplitude adjusted, And a first synthesizer that synthesizes the other fundamental wave signal distributed by the distributor and outputs it to the carrier amplifier circuit.

[First Embodiment: FIG. 1]
A high-frequency power amplifier according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a high-frequency power amplifier (first amplifier) according to the first embodiment of the present invention.
As shown in FIG. 1, in the Doherty amplifier, the first amplifier includes a harmonic reflection circuit that reflects the second harmonic in the carrier amplification circuit 6 and the peak amplification circuit 7, and the input signal is input to the preceding stage of the Doherty amplifier. In this configuration, a harmonic generation circuit 3 for injecting second harmonics is provided.

  Specifically, the first amplifier includes an input terminal 1, a harmonic generation circuit 3, a distributor 4, a phase shifter 5, a carrier amplifier circuit 6, a peak amplifier circuit 7, a transmission line 8, and 10 and a composite point 9. That is, the first amplifier has a configuration in which the harmonic generation circuit 3 is added to the Doherty amplifier including the conventional harmonic reflection circuit shown in FIG. Since it is the same as the Doherty amplifier provided with the conventional harmonic reflection circuit shown in FIG.

  Here, the amplifier 20 is a Doherty amplifier including the conventional harmonic reflection circuit shown in FIG. The harmonic reflection circuit provided in the carrier amplification circuit and the peak amplification circuit has an impedance characteristic that reflects the second harmonic without affecting the fundamental wave. Note that the harmonic reflection circuit may be provided in front of each output matching circuit.

[Configuration of Harmonic Generation Circuit 3: FIG. 2]
The configuration of the harmonic generation circuit 3 that is a feature of the first amplifier will be described with reference to FIG. FIG. 2 is a configuration block diagram of the harmonic generation circuit 3.
As shown in FIG. 2, the harmonic generation circuit 3 of the first amplifier is a circuit that generates harmonics injected into the input of the amplifier 20, and includes a distributor 31, a delay line 35, and second harmonic generation. The amplifier 32, the variable phase shifter 33, the variable attenuator 34, and the synthesizer 36 are connected to the amplifier 20.

The distributor 31 distributes the input signal from the input terminal 1.
The harmonic generator 32 generates harmonics, and the first amplifier generates second harmonics.

The variable phase shifter 33 adjusts the phase of the second harmonic generated by the harmonic generator 32.
The variable attenuator 34 adjusts the amplitude of the second harmonic generated by the harmonic generator 32.
The portion composed of the variable phase shifter 33 and the variable attenuator 34 corresponds to a vector adjuster that performs vector adjustment of the generated second harmonic, and the variable phase shifter 33, the variable attenuator 34, and the harmonic generator. The arrangement order of 32 may be changed.

  In the variable phase shifter 33 and the variable attenuator 34, the relationship between the phase and amplitude of the second harmonic generated by the harmonic generator 32 and the phase and amplitude of the second harmonic generated by the amplifier 20 is optimized. In addition, the phase shift and the amplitude level ratio between the fundamental wave and the second harmonic are adjusted to be optimal.

The delay line 35 delays the input signal (fundamental wave) from the distributor 31 by the processing time in the harmonic generator 32, the variable phase shifter 33, and the variable attenuator 34.
Then, the synthesizer 36 synthesizes the delayed fundamental wave signal and the second harmonic whose phase and amplitude are output from the variable attenuator 34 and outputs the synthesized result to the amplifier 20.

  As described above, the harmonic generation circuit 3 is composed of an analog circuit with a simple configuration, and includes a vector adjustment circuit that adjusts the phase shift between the fundamental wave and the second harmonic and the necessary amplitude level ratio. The output level and phase of the harmonics necessary for the amplifier 20 can be accurately adjusted, and the amplification operation in the amplifier 20 can be performed with high efficiency.

  Here, the variable phase shifter 33 for adjusting the phase and the variable attenuator 34 for adjusting the amplitude are used. However, the adjustment for adjusting the phase and amplitude of the harmonic generated by the harmonic generator 32 is used. As long as the phase and amplitude can be adjusted as a device, any method may be used as long as it has an equivalent function.

  In particular, in the first amplifier, paying attention to the second-order harmonic having a high level among the generated harmonics, the second-order harmonic is injected into the input of the amplifier, and the second-order harmonic is efficiently output by the harmonic reflection circuit. Since the harmonics are reflected, the effect of improving the efficiency is increased.

[Configuration of Harmonic Generator 32]
The configuration of the harmonic generator 32 of the harmonic generation circuit 3 will be briefly described.
The harmonic generator has a configuration in which an input terminal, an input matching circuit, a diode, an output matching circuit, and an output terminal are connected in series. The diode generates a second harmonic using the fundamental wave input from the input terminal. The input matching circuit is an impedance conversion circuit that is matched to the fundamental wave in order to transmit the input signal without waste. The output matching circuit outputs the second harmonic generated from the diode as efficiently as possible. It is an impedance conversion circuit matched to the second harmonic.
Although the configuration in the case of using a diode has been described here, it can also be configured by using an amplifying element, and another method may be used as long as second harmonics are generated.

[Operation of the first amplifier]
The operation of the first amplifier will be described with reference to FIGS.
In the first amplifier, the fundamental wave signal inputted from the input terminal 1 of FIG. 1 is inputted to the harmonic generation circuit 3 and distributed by the distributor 31 of the harmonic generation circuit 3 of FIG. The wave signal is input to the harmonic generator 32, and a second harmonic having a frequency twice the fundamental frequency is generated.
The generated second harmonic is phase-adjusted by the variable phase shifter 33, amplitude-adjusted by the variable attenuator 34, and input to the synthesizer 36.

The other fundamental wave signal distributed by the distributor 31 of the harmonic generator 3 is delayed by the delay line 35 and input to the synthesizer 36, and the synthesizer 36 synthesizes it with the vector-adjusted second harmonic. And output to the distributor 4 of the Doherty amplifier of FIG.
The signal input to the carrier amplifier 6 is amplified and output to the synthesis point 9 through the transmission line 8, and the signal input to the peak amplifier 7 via the phase shifter 5 is amplified and output to the synthesis point 9. After being synthesized at the synthesis point 9, the signal is output from the output terminal via the transmission line 10.

  That is, in the first amplifier, the signal input to the carrier amplifier circuit 6 and the peak amplifier circuit 7 of the Doherty amplifier contains a lot of second harmonics, so the output level of the second harmonics increases, and the carrier amplifier 6 In addition, the second harmonic reflection level reflected to the FETs 62 and 72 by the harmonic reflection circuits 64 and 74 of the peak amplifier 7 can be further increased, and the overlapping of voltage and current waveforms can be reduced to improve the power efficiency. It is something that can be done.

[Effect of the first embodiment]
According to the high frequency power amplifier (first amplifier) according to the first embodiment, in the Doherty amplifier in which the carrier amplifier circuit 6 and the peak amplifier circuit 7 include the harmonic reflection circuits 64 and 74, respectively, the input of the Doherty amplifier A stage includes a harmonic generator 32 that generates a second harmonic, a variable phase shifter 33 that adjusts the phase of the generated second harmonic, and a variable attenuator 34 that adjusts the amplitude of the second harmonic. The harmonic output level of the FET is increased by using a composite signal in which the second harmonic is injected into the fundamental wave signal as an input signal of the Doherty amplifier, and the reflection level of the second harmonic in the harmonic reflection circuits 64 and 74 is increased. Is increased, the overlap of voltage and current waveforms is reduced, and the power efficiency can be improved.

  Further, by adjusting the variable phase shifter 33 and the variable attenuator 34 of the harmonic generation circuit 3, the phase and amplitude of the second harmonic injected into the fundamental wave by the harmonic generation circuit 3 can be adjusted by the Doherty amplifier. It can be adjusted to have an optimum relationship with the phase and amplitude of the generated second harmonic, and there is an effect that the efficiency can be further improved with a simple configuration.

  Conventionally, in order to adjust the phase and amplitude of the second harmonic, the harmonic reflection circuit must be adjusted, and the output matching circuit must also be adjusted together with the fundamental matching and the second harmonic. Although it is difficult to match the wave matching at the same time, according to the second amplifier, the second harmonic is added to the input signal, and the phase of the second harmonic is changed by the variable phase shifter 33 and the variable attenuator 34. By adjusting the amplitude, there is an effect that it becomes easy to match the matching of the fundamental wave and the second harmonic at the same time.

[Efficiency in harmonic generator: Fig. 3]
The first amplifier improves the efficiency of the Doherty amplifier, which is the main amplifier, by injecting harmonics. However, if the efficiency of the harmonic generation circuit is low, the efficiency of the entire device decreases. End up.
Therefore, in order to further improve the efficiency of the Doherty amplifier, it is conceivable to improve the efficiency of the harmonic generation circuit.

FIG. 3 shows input / output power consumption characteristics in the harmonic generation circuit. FIG. 3 is a schematic explanatory diagram showing input / output-power consumption characteristics in the harmonic generation circuit, where (a) is a general second harmonic generator, and (b) is a saturated second harmonic generator. It is a characteristic. In FIG. 3, the solid line schematically shows the output level, and the dotted line schematically shows the power consumption. The arrows in the figure indicate that the output level refers to the left vertical axis, and the power consumption refers to the right vertical axis. .
As shown in FIG. 3 (a), in a general second-order harmonic generator, when the maximum output is increased, the power consumption with respect to the output level is very high at the backoff level (where the input power is low). Big and low efficiency. In consideration of efficiency, it is desirable to use the device where the back-off is as low as possible (close to saturation).

On the other hand, as shown in FIG. 3B, when a saturation type second harmonic generator having a characteristic that the maximum output level is low and reaches saturation at a low input level is used, the power consumption for the output level is small, A sufficiently good efficiency can be obtained even at a low input level.
Therefore, further improvement in efficiency can be achieved by using a saturation type second harmonic generator in which the maximum output level is a necessary and sufficient level (not larger than necessary) in the second harmonic generation circuit. It is.

[Second Embodiment: FIG. 4]
A high-frequency power amplifier according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of a high-frequency power amplifier (second amplifier) according to the second embodiment of the present invention.
The second amplifier includes a harmonic generation circuit at the input stage of the Doherty amplifier including the harmonic reflection circuit, and injects harmonics into the peak amplification circuit, and further includes harmonics of the harmonic generation circuit. As the generator, the above-described saturation type second harmonic generator is provided.

As shown in FIG. 4, the second amplifier includes an input terminal 1, a harmonic generation circuit 3, a distributor 4, a phase shifter 5, a combiner 65, a carrier amplification circuit 6, and a peak amplification circuit. 7, transmission lines 8 and 10, and a synthesis point 9.
The distributor 4 corresponds to the first distributor in the claims, and the combiner 65 corresponds to the first combiner in the claims.

The configuration of the carrier amplifier circuit 6 is the same as that of the first amplifier, and includes a harmonic reflection circuit 64 that reflects the second harmonic. The harmonic reflection circuit 64 corresponds to the first harmonic reflection circuit in the claims.
The peak amplifier circuit 7 has the same configuration as that of a typical conventional Doherty amplifier, and no harmonic reflection circuit is provided.

  The second harmonic output from the harmonic generation circuit 3 is combined with the fundamental wave at the combining point 65 and input to the carrier amplifier circuit 6.

[Harmonic wave generation circuit 3: FIG. 4]
The harmonic generation circuit 3 which is a characteristic part of the second amplifier will be specifically described.
As shown in FIG. 4, the harmonic generation circuit 3 of the second amplifier includes a distributor 31, a delay line 35, a variable attenuator 34, a saturation type second harmonic generator 37, and a variable attenuator 33. It consists of.
The distributor 31 distributes the input signal from the input terminal 1.
The saturation type second harmonic generator 37 is a harmonic consisting of an element having a characteristic that the maximum output of the second harmonic is saturated at a low input level at a level sufficient to improve the efficiency of the Doherty amplifier. Generator.

The basic configuration of the saturation type second harmonic generator 37 is almost the same as the harmonic generator 32 of the first amplifier, and includes an input terminal, an input matching circuit, an FET, an output matching circuit, and an output. The terminal is connected in series. The FET receives the fundamental wave input from the input terminal and generates a second harmonic.
In other words, in the saturation type second harmonic generator 37, an FET element that is saturated at a specific output level and does not output a second harmonic output more than necessary is selected, and the first amplifier generates harmonics. Power consumption is reduced compared to the device.

In the second amplifier, if the carrier amplifier (FET 62 of the carrier amplifier circuit 6) starts to saturate, that is, if the maximum output level of the carrier amplifier circuit and the peak amplifier (FET 72 of the peak amplifier circuit 7) is the same, the Doherty By saturating near the optimum second harmonic level near the 6 dB backoff point of the amplifier output, the power consumption in the harmonic generator can be kept low, and the efficiency of the entire apparatus is increased.
That is, since the harmonic generator of the second amplifier saturates at a low input level, it can be used in a saturation region from a low input level, the power conversion efficiency is good, and the overall efficiency can be greatly improved. Is.

The variable attenuator 34 adjusts the optimum level of the second harmonic injected from the harmonic generation circuit 3 into the carrier amplification circuit 6. The maximum level of the second harmonic is adjusted by the power supply voltage that determines the saturation of the saturation type second harmonic generator 37.
The variable phase shifter 33 adjusts the phase of the second harmonic output from the saturation type second harmonic generator 37.
Note that the variable phase shifter 33 may be provided before the saturation type second harmonic generator 37. The variable attenuator 34 may be a stage subsequent to the saturation type second harmonic generator 37 when the variable amount is small.

[Operation of Second Amplifier: FIG. 4]
The operation of the second amplifier will be described with reference to FIG.
In the second amplifier, the fundamental wave signal input from the input terminal 1 is input to the harmonic generation circuit 3 and distributed by the distributor 31, and one of the fundamental wave signals has an optimum level by the variable attenuator 34. Adjustment is performed and input to the saturation type second harmonic generator 37 to generate a second harmonic having a frequency twice the fundamental frequency, and the phase is adjusted by the variable phase shifter 33, and the combiner 65 Is input.
The harmonic generation circuit 3 generates a second harmonic having a necessary and sufficient level when injected into the input of the carrier amplifier circuit 6 and prevents the saturation second harmonic generation circuit 37 from becoming higher than necessary. Use to adjust the power supply voltage.

The other fundamental wave signal distributed by the distributor 31 is delayed by the delay line 35 and delayed in phase, and branched by the distributor 4 to the carrier amplifier 6 side and the peak amplifier 7 side.
The fundamental wave signal distributed to the carrier amplifier 6 side is input to the synthesizer 36, and is combined with the vector-adjusted second harmonic by the synthesizer 36, and the combined signal is input to the carrier amplifier circuit 6.

On the other hand, the signal distributed to the peak amplifier 7 side by the distributor 4 is phase-adjusted by the phase shifter 5, amplified by the peak amplifier 7, and output to the synthesis point 9.
The signal input to the carrier amplifier 6 is amplified and output to the synthesis point 9 via the transmission line 8. After being combined with the signal output from the peak amplifier 7 at the synthesis point 9, the signal is output from the output terminal 2 via the transmission line 10. Is output.

  That is, since the second harmonic is included in the composite signal input to the carrier amplifier circuit 6, the second harmonic generated at the drain terminal of the FET 62 of the carrier amplifier circuit 6 is higher than the conventional level, and the harmonics The second-order harmonic reflection level reflected by the reflection circuit 64 can be further increased, voltage current waveform overlap can be reduced, and power efficiency can be improved.

[Effect of the second embodiment]
According to the high frequency power amplifier (second amplifier) according to the second embodiment, in the Doherty amplifier in which the carrier amplifier circuit 6 includes the harmonic reflection circuit 64, the second harmonic is applied to the input stage of the Doherty amplifier. A harmonic generation circuit 3 is provided, and a second harmonic is injected into the input of the carrier amplifier circuit 3 to increase the level of the second harmonic in the carrier amplifier circuit 6 operating in a wide input level range. The efficiency is improved by wave reflection, and the harmonic generation circuit 3 includes a saturation type second harmonic generator 37 that saturates at a necessary and sufficient level, a variable phase shifter 33, and a variable attenuator 34. As a result, it is possible to saturate the level of the second harmonic at a necessary and sufficient level and further adjust the level to an optimum level, thereby reducing the power consumption in the harmonic generation circuit 3 and improving the effectiveness of the entire Doherty amplifier. There is an effect capable of further improving.

  In particular, in the second amplifier, the saturation level of the second harmonic output from the saturation type second harmonic generator 37 is adjusted so that the efficiency is improved in the vicinity of the point where the maximum output of the Doherty amplifier is reduced by 6 dB. Therefore, there is an effect that the efficiency of the entire apparatus can be improved.

Further, in the Doherty amplifier, the efficiency is originally high in the region where the peak amplifier circuit 7 operates, and since the time during which the peak amplifier circuit 7 operates is short, the influence of the efficiency of the peak amplifier circuit 7 on the whole is not so great.
In the second amplifier, the second harmonic is injected only to the input of the carrier amplifier circuit 6 by utilizing this fact. Therefore, the apparatus configuration is simplified, and the power required for the injection of the second harmonic. In particular, in the wide input level region where only the carrier amplifier circuit 6 operates, there is an effect that the efficiency can be significantly improved.
In the case where only the carrier amplifier circuit 6 is used to inject harmonics, the peak amplifier circuit 7 may be provided with a harmonic reflection circuit.

[Third Embodiment: FIG. 5]
Next, a high frequency amplifier according to a third embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of a high-frequency amplifier (third amplifier) according to the third embodiment of the present invention.
As with the second amplifier, the third amplifier is provided with a harmonic reflection circuit in the carrier amplifier circuit and injects a second harmonic into the input, and a peak reflection circuit is also provided with a harmonic reflection circuit to provide peak amplification. Second harmonics are injected into the circuit input. In addition, the harmonic generator is a saturated type to reduce power consumption.

As shown in FIG. 5, the third amplifier includes a distributor 38, a combiner 75, and a harmonic reflection circuit 74 in addition to the configuration of the second amplifier shown in FIG. 4. . Since other parts are the same as those of the second amplifier, description thereof is omitted.
The distributor 38 corresponds to the second distributor in the claims, the combiner 75 corresponds to the second combiner in the claims, and the harmonic reflection circuit 74 corresponds to the second harmonic reflection circuit in the claims. It corresponds to.

The distributor 38 distributes the phase-adjusted second harmonic generated by the saturation type second harmonic generator 37 to the carrier amplifier circuit 6 side and the peak amplifier circuit side.
The synthesizer 75 synthesizes the fundamental wave signal that has been distributed by the distributor 4 and phase-adjusted, and the second harmonic that has been distributed by the distributor 38, and outputs the combined signal to the peak amplifier circuit 7.
The harmonic reflection circuit 74 reflects the second harmonic output from the FET 72 and improves the efficiency of the peak amplification circuit 7.

In the third amplifier, the second-order harmonic of the optimum level generated by the harmonic generation circuit 3 is distributed by the distributor 38, and one is combined with the fundamental wave by the combiner 65 and input to the carrier amplifier circuit 6. The other is combined with the fundamental wave by the combiner 75 and input to the peak amplifier circuit 7, amplified respectively, combined at the combining point 9, and output from the output terminal 2 via the transmission line 10.
In this way, the operation of the third amplifier is performed.

[Effect of the third embodiment]
According to the high frequency power amplifier (third amplifier) according to the third embodiment, in the Doherty amplifier in which the carrier amplifier circuit 6 and the peak amplifier circuit 7 include the harmonic reflection circuits 64 and 74, respectively, the input of the Doherty amplifier The stage includes a harmonic generation circuit 3 that generates a second harmonic, and injects the second harmonic into the inputs of the carrier amplification circuit 6 and the peak amplification circuit 7, so that the carrier amplification circuit 6 and the peak amplification circuit 7 In both cases, efficiency is improved by harmonic reflection, and further, the harmonic generation circuit 3 is saturated with a necessary and sufficient level, a saturated second harmonic generator 37, a variable phase shifter 33, a variable attenuator 34, The second harmonic level is saturated at a necessary and sufficient level, and the second harmonic level can be adjusted to an optimum level, thereby reducing the power consumption in the harmonic generation circuit 3. Te, there is an effect that it is possible to further improve the overall efficiency of the Doherty amplifier.

  In addition, when changing the injection amount and phase of the second harmonic of the carrier amplifier circuit 6 and the peak amplifier circuit 7, a phase shifter and an attenuator can be provided corresponding to each.

  The present invention is suitable for a high-frequency power amplifier capable of improving power conversion efficiency.

1 is a configuration block diagram of a high-frequency power amplifier (first amplifier) according to a first embodiment of the present invention. 3 is a block diagram illustrating a configuration of a harmonic generation circuit 3. FIG. It is a model explanatory drawing which shows the input-output-power consumption characteristic in a harmonic generation circuit, (a) is a general 2nd harmonic generator, (b) is a characteristic in a saturation type 2nd harmonic generator. It is a block diagram of the configuration of a high-frequency power amplifier (second amplifier) according to a second embodiment of the present invention. FIG. 5 is a configuration block diagram of a high-frequency amplifier (third amplifier) according to a third embodiment of the present invention. It is a block diagram which shows the structure of the Doherty amplifier provided with the conventional harmonic reflection circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... Output terminal, 3 ... Harmonic generation circuit, 4 ... Distributor, 5 ... Phase shifter, 6 ... Carrier amplifier circuit, 7 ... Peak amplifier circuit, 8, 10 ... Transmission line, 61, 71 ... Input matching circuit, 62,72 ... FET, 63,73 ... Output matching circuit, 64,74 ... Harmonic reflection circuit, 20 ... Amplifier, 31 ... Distributor, 32 ... Harmonic generator, 33 ... Variable phase shifter 34 ... Variable attenuator 35 ... Delay line 36 ... Synthesizer

Claims (2)

A carrier amplifier circuit having a first amplifier element operating in class AB;
A peak amplifying circuit having a second amplifying element operating in class B or C,
A high-frequency power amplifier having a Doherty amplifier that combines and outputs the outputs of the carrier amplifier circuit and the peak amplifier circuit,
The carrier amplification circuit includes a first harmonic reflection circuit that reflects a second harmonic frequency output from the first amplification element,
A high frequency power characterized in that a second harmonic of the fundamental frequency that saturates at a specific level is synthesized with an input signal of the fundamental frequency input to the carrier amplifier circuit and input to the carrier amplifier circuit. amplifier. The peak amplification circuit includes a second harmonic reflection circuit that reflects the second harmonic frequency output from the second amplification element;
The second harmonic of the fundamental frequency that saturates at a specific level is synthesized with an input signal of the fundamental frequency that is input to the peak amplifier circuit, and is input to the peak amplifier circuit. The high frequency power amplifier according to 1.

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