JP2002124840A - Doherty amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in a conventional Doherty amplifier, as the bias conditions of two amplifiers are different, the output power from each amplifier at the output terminal is not effectively put together, and therefore the output power and efficiency are reduced. SOLUTION: A Doherty amplifier comprises: a carrier amplifier 3 which is biased in A class, AB class or B class; a 1/4 wavelength line 5; a peak amplifier 4 which is biased in B class or C class; a variable attenuator 7 for changing the gain; and a variable phase shifter 8 for changing the through phase amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power amplifier for amplifying a modulated wave signal in a high frequency band.
In particular, the present invention relates to a Doherty-type amplifier that realizes a high-efficiency high-output amplifier even in an operation state with a large back-off.

[0002]

2. Description of the Related Art In a high-frequency band such as a VHF band, a UHF band or a microwave band, a QPSK (Quadriphase P) is used.
hase Shift Keying) and QAM (Quadrature Amplitude Mo
Communication is performed using various modulation methods such as dulation). In general, the amplitude of a high-frequency signal used in these communications changes with time according to the cycle of a modulated wave.
That is, the envelope of the high-frequency signal changes with time. Also, when a plurality of signals are simultaneously amplified in a mobile communication base station or the like, superimposed signals related to the plurality of signals change with time. FIG. 13 is a diagram illustrating an example of a waveform of a high-frequency signal. The so-called instantaneous peak power of the high-frequency signal shown in FIG. 13 in a state where the amplitude of the envelope is instantaneously maximized is larger than the average power. The ratio between the average power and the peak power is called a peak power ratio or a crest factor. For high-frequency signals used in mobile communication base stations in recent years, the value of the peak power ratio may reach 11 dB or more. In order to amplify such a high-frequency signal having a large peak power ratio without saturating even at the moment of an instantaneous peak, the high-output amplifier must have a sufficiently large saturation power compared to the average output power in actual operation. Must. If the saturation power of the amplifier is insufficient, the signal output from the amplifier will have a waveform in which a large portion of the instantaneous power is cut off, and as a result, the interference wave leaking to the adjacent channel will increase, There are adverse effects such as deterioration of the transmitted signal and an increase in transmission error. That is, the amplifier needs to be operated in a state where the back-off given as the difference between the average output power and the saturation power in actual operation is sufficiently large.

[0003] However, it is difficult to achieve both high saturation power and high efficiency. Generally, in a high-output amplifier in a high-frequency band, an output matching circuit of the amplifier is adjusted according to required characteristics to optimize a load impedance on an output side as viewed from an amplifying element such as an FET.
For example, there are cases where a load impedance condition for increasing the efficiency is selected, and cases where a load impedance condition for increasing the saturation power is selected. However, as described in, for example, “Basics and Applications of MMIC Technology (Realize, Takagi, Ito, especially see FIG. 8.39 (a)” on page 155), a load that increases efficiency is generally used. The impedance condition does not match the load impedance condition for increasing the saturation power. Moreover, the load impedance that achieves the maximum efficiency changes according to the output power. FIG.
6 is a Smith chart showing the relationship between output-side load impedance, saturation power, and efficiency of an amplifying element such as an FET. The regions where the saturation power and the efficiency are equal are shown as contour lines on the Smith chart. Generally, the load impedance for increasing the saturation power does not match the load impedance for increasing the efficiency.
Under the load impedance condition with high efficiency, the saturation power is insufficient, and as a result, the modulated wave signal has a waveform with the peak cut off, and good communication cannot be realized. On the other hand, under the load impedance condition where the saturation power becomes large, the peak of the modulated wave is not cut off, but the efficiency as the amplifier is reduced.

As is apparent from the above reasons, it has been difficult to construct an amplifier having high saturation power and high efficiency. In other words, in a state where the saturation power is large as compared with the average output power, that is, in a state where the back-off is large, generally, the efficiency of the amplifier is greatly reduced. For example, in a simple class-B amplifier, the theoretical maximum efficiency during saturation operation is 78%, but the maximum theoretical efficiency during operation with a back-off of 10 dB is 26%. For this reason, the efficiency of a high power amplifier for a base station, which needs to amplify a signal having a large peak power ratio as described above with low distortion, has been low.

[0005] In order to solve the problems relating to the saturation power and efficiency of the amplifier as described above, a microwave Doherty amplifier (Doherty amplifier) has been developed. FIG. 15 is a diagram showing a configuration of a conventional microwave Doherty amplifier disclosed in, for example, JP-A-7-22852. FIG.
5, 101 is an input terminal, 102 is an output terminal, 1
03 is a quarter wavelength line, 104 is A class, AB class or B
105 is a carrier amplifier provided as a class-biased amplifier, 105 is a class B or a peak amplifier provided as a class B biased current, that is, a class C-biased amplifier, 106 is a 1/4 wavelength line, and 107 is This is an output load having an impedance of R / 2 for convenience (R can take any value).

Next, the operation will be described. Input terminal 10
The high-frequency signal input from 1 is distributed to two paths. In one path, the high-frequency signal is input to the carrier amplifier 104, and the output signal from the carrier amplifier 104 is input to the 波長 wavelength line 106. In the other path, a high-frequency signal is input to the peak amplifier 105 after passing through the 波長 wavelength line 103. Then, the high frequency signals distributed to the two paths and transmitted respectively are combined, and the output terminal 102
And supplies it to the output load 107.

When the instantaneous input power is small, the carrier amplifier 104 is biased to class A, class AB, or class B, and performs an amplifying operation regardless of the power level of the input signal to output an output signal. On the other hand, the peak amplifier 105
Are biased to class B or class C, and when the instantaneous input power is small, the output signal is not output without the off state, that is, without performing the amplification operation. Also, the peak amplifier 10
Since the DC power consumption of No. 5 is also zero or sufficiently small, the efficiency of the entire microwave Doherty amplifier is high.

On the other hand, when the instantaneous input power is sufficiently large, the peak amplifier 105 is turned on and amplifies the input signal to the peak amplifier 105 to generate an output signal.
At this time, by combining the output power of the carrier amplifier 104 and the output power of the peak amplifier 105, an amplifier having a larger saturation power is configured as a result.

However, the microwave Doherty amplifier is not simply provided as a circuit in which an amplifier biased to class A, class AB or class B and an amplifier biased to class B or class C are simply combined. Absent. 1/4 wavelength line 106 provided on the output side of carrier amplifier 104
By changing the apparent load impedance of the carrier amplifier 104 based on the above function, further higher efficiency is realized.

FIG. 16 is a diagram showing an operation state of the microwave Doherty amplifier when the power level of the input signal is small. Since the peak amplifier 105 is in the off state, its output impedance is ideally infinite. 1 provided on the output side of the carrier amplifier 104
Since the characteristic impedance Zc of the 波長 wavelength line 106 is R, the output load 107 is subjected to impedance conversion, and the load impedance seen from the output terminal of the carrier amplifier 104 becomes 2R. When the load impedance is 2R, the carrier amplifier 104 is designed so that the saturation power is small but the efficiency is good. Therefore, in such an operating state, the carrier amplifier 104 operates at the maximum efficiency.

When the power level of the input signal is large, an operation state as shown in FIG.
Since the carrier amplifier 104 and the peak amplifier 105 are connected in parallel with each other and both amplifiers output power, the load impedance seen by each load when the output load 107 is connected is equal to the output load 10.
R becomes twice the impedance of 7. Since the characteristic impedance of the 波長 wavelength line 106 provided on the output side of the carrier amplifier 104 is R, the impedance conversion by this line is not performed, and the carrier amplifier 104
The load impedance viewed from the output terminal of the first circuit also becomes R. When the load impedance is R, the carrier amplifier 104
Both the peak amplifier 105 and the peak amplifier 105 are designed to have a large saturation power, so that a large saturation power can be obtained as a whole of the microwave Doherty amplifier. In such an operation state, the microwave Doherty amplifier operates in a state close to the saturation power, so that the efficiency is high.

As described above, the microwave Doherty amplifier has a peak amplifier 105 when the power of the input signal is large.
Operates, the two output powers of the carrier amplifier 104 and the peak amplifier 105 are combined to increase the saturation power, and the apparent load of the carrier amplifier 104 depends on whether the input signal power is small or large. With the effect that the impedance can be changed and the operation can be performed with high efficiency, a highly efficient operation can be realized even in a state where the back-off is large. In the circuit configuration described above, the quarter wavelength line 106 is provided to change the apparent load impedance of the carrier amplifier 104, but the quarter wavelength line 106 is replaced with the quarter wavelength line 106. A similar effect can be obtained by arranging a line (n is an arbitrary natural number).
A 1/4 wavelength line 1 is connected to the input side of the peak amplifier 105.
Instead of disposing 03, a 90-degree distributor that distributes a high-frequency signal with a 90-degree phase difference can be used.

[0013]

Since the conventional Doherty-type amplifier is configured as described above, even if the carrier amplifier and the peak amplifier operate simultaneously at a time when the power of the input signal is large, the carrier amplifier is not used. In general, since the bias conditions of the amplifier and the peak amplifier are different from each other, the passing phase amounts of the two amplifiers are not necessarily equal. Also, the gains of the two amplifiers are generally not equal. Therefore, when the passing phase amounts of the two amplifiers are not equal, the output power and efficiency are reduced because the output powers from the amplifiers at the output end are not effectively combined.

FIG. 17 is a diagram showing the relationship between input power and output power (AM-AM characteristics) of the Doherty amplifier. In order to achieve good overall efficiency, gain and distortion characteristics by combining the carrier amplifier and the peak amplifier, the power level Pon at which the peak amplifier is turned on as shown in FIG. It is necessary to optimize the change in output power with respect to the change in input power after that, that is, the AM-AM characteristic. However, the power level P which is turned on for the peak amplifier
If the on-state or the AM-AM characteristic deviates from a desired value, there is a problem that the efficiency of the entire Doherty amplifier configured by combining with the carrier amplifier is reduced or the overall linearity is deteriorated.

A peak amplifier mainly provided as a class C amplifier has a relationship between input power and output power (AM-AM
Not only has a large non-linearity in the characteristic, but also the relationship between the input power and the passing phase amount (AM-PM characteristic) changes. For this reason, the passing phase amount of the peak amplifier changes with an increase in the input power, and the output power from the carrier amplifier and the output power from the peak amplifier at the output end are not effectively combined. There has been a problem that output power and efficiency are reduced.

In general, the characteristics of an amplifier change according to changes in the ambient temperature. Doherty amplifiers use two types of amplifiers with greatly different bias conditions.
A characteristic difference between the two amplifiers due to a temperature change is likely to appear. Therefore, there is a problem in that output power and efficiency are reduced because the output power is not effectively combined because a difference occurs in the amount of passing phase between the carrier amplifier and the peak amplifier due to a temperature change.

Furthermore, in a Doherty amplifier, unlike an ordinary parallel amplifier, two amplifiers having different bias conditions are used, so that the balance between the two amplifiers deteriorates. FIG. 18 is a diagram showing a loop formed in the Doherty amplifier. As described above, the Doherty amplifier has a poor balance between the two amplifiers and a long circuit path using the quarter wavelength line, so that the path in which the carrier amplifier 104 is arranged and the peak amplifier 1
There is a problem in that a phenomenon such as unnecessary loop oscillation is likely to occur in a loop that goes around the route where the 05 is arranged. In a normal parallel amplifier, since two amplifiers operate in the same state, the balance is good, and the problem of loop oscillation is not as serious as that of a microwave Doherty amplifier.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in order to prevent a decrease in output power and efficiency, a Doherty-type amplifier capable of changing a passing phase amount of a carrier amplifier or a peak amplifier is provided. The purpose is to gain.

Further, the present invention provides a Doherty-type amplifier capable of compensating for a difference in the amount of passing phase between a carrier amplifier and a peak amplifier due to a temperature change in order to prevent a decrease in output power and efficiency. The purpose is to gain.

A further object of the present invention is to provide a Doherty amplifier capable of changing the AM-AM characteristics and the AM-PM characteristics of a peak amplifier in order to prevent a decrease in output power and efficiency.

A further object of the present invention is to provide a Doherty amplifier capable of preventing loop oscillation.

[0022]

A Doherty amplifier according to the present invention is arranged in an input terminal and a first path extending from the input terminal and biased to class A, class AB or class B. A 1/4 + n / 2 wavelength line (n is 0 or an arbitrary natural number) disposed on the output side of the first amplifier in the first path, and a class B disposed on the second path extending from the input terminal. Or a second amplifier biased to class C, an output terminal arranged at a portion where the first path and the second path are coupled on the output side of the first amplifier and the second amplifier, Correction means for correcting one or both of the amount of passing phase and the gain of the high-frequency signal transmitted through the second path or the high-frequency signal transmitted through the second path.

The Doherty-type amplifier according to the present invention is provided with a variable attenuator and a variable phase shifter arranged on the input side of the first amplifier or the second amplifier as correction means.

The Doherty amplifier according to the present invention is based on a temperature sensor, storage means for storing a set value related to control of a variable attenuator and a variable phase shifter as a function of temperature, and a temperature measured by the temperature sensor. And control means for reading the set values related to the control of the variable attenuator and the variable phase shifter from the storage means and controlling the variable attenuator and the variable phase shifter.

The Doherty-type amplifier according to the present invention includes a delay circuit disposed on the input side or the output side of the first amplifier or the second amplifier as the correction means.

The Doherty amplifier according to the present invention is provided with a frequency equalizer arranged on the input side or the output side of the first amplifier or the second amplifier as the correction means.

In the Doherty amplifier according to the present invention, the AM-AM characteristic, which is the relationship between the input power and the output power of the second amplifier, and the relationship between the input power and the amount of passing phase of the second amplifier, as correction means. An AM-AM / PM adjuster for adjusting the AM-PM characteristic is provided.

A Doherty-type amplifier according to the present invention is arranged in an input terminal and a first path extending from the input terminal.
A first amplifier biased to class, class AB or class B, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed at an output side of the first amplifier in a first path; , Disposed on a second path extending from the input terminal,
A second amplifier biased to a class or a class C, and a first signal converter disposed on an input side of the first amplifier in a first path and converting a baseband signal input from an input terminal to a high-frequency signal Means, a second signal conversion means disposed on the input side of the second amplifier in the second path, for converting a baseband signal input from the input terminal into a high-frequency signal, and a first amplifier and a second signal conversion means. An output terminal arranged at a portion where the first path and the second path are coupled on the output side of the amplifier; and a baseband signal transmitted through the first path or a baseband signal transmitted through the second path And correction means for correcting one or both of the passing phase amount and the gain.

The Doherty amplifier according to the present invention has a first
And a second signal converting means for converting a baseband signal provided as a digital signal into an analog high-frequency signal.

In the Doherty amplifier according to the present invention, as the correction means, the level detection means detects the power level of the baseband signal transmitted through the first path or the second path, and the level detection means detects the power level. A storage unit in which control data corresponding to the power level is stored, and a control unit that performs control of one or both of the amplitude and the phase of the baseband signal according to the detected power level,
Conversion means for converting one or both of the amplitude and the phase of the baseband signal in accordance with a control signal from the control means.

In the Doherty amplifier according to the present invention, as correction means, distribution means for extracting a part of the high-frequency signal transmitted through the first path or the second path, and conversion of the extracted high-frequency signal as a digital signal Signal inverting means for converting to a baseband signal, level detecting means for detecting the power level of the baseband signal transmitted through the first path or the second path, Based on the control data and the data relating to the characteristics of the first amplifier or the second amplifier, and the power level detected by the level detecting means and the baseband signal fed back from the signal inverting means. Controlling one or both of the amplitude and the phase of the baseband signal transmitted through the first path or the second path And control means that is obtained by so and a converting means for converting either or both of the baseband signal amplitude and phase according to a control signal from the control means.

In the Doherty-type amplifier according to the present invention, the control means may include a baseband signal fed back from the signal inversion means, and data relating to characteristics of the first amplifier or the second amplifier stored in the storage means. In contrast to this, the control data stored in the storage means is rewritten.

A Doherty amplifier according to the present invention is arranged on an input terminal and a first path extending from the input terminal and having an A terminal.
A first amplifier biased to class, class AB or class B, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed at an output side of the first amplifier in a first path; , Disposed on a second path extending from the input terminal,
A second amplifier biased to class C or class C, an output terminal arranged at a portion where the first path and the second path are coupled at the output side of the first amplifier and the second amplifier, A first isolator disposed on the input side of one amplifier and a second isolator disposed on the input side of the second amplifier are provided.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 1 of the present invention. In FIG. 1, 1 is an input terminal, 2 is an output terminal, and 3 is disposed on a first path extending from the input terminal 1 and is biased to class A, class AB, or class B and always operates regardless of the magnitude of instantaneous power. Carrier amplifier (first amplifier) provided as an amplifier for amplifying an input signal by
Are provided in a second path extending from the input terminal 1 and are biased to class B or class C, do not operate when the instantaneous power is small, and operate only when the instantaneous power is large to amplify the input signal. The peak amplifier (second amplifier) 5 is disposed on the output side of the carrier amplifier 3.
波長 wavelength line, 6 is a 波長 wavelength line arranged on the input side of the peak amplifier 4, 7 is a variable attenuator arranged on the input side of the peak amplifier 4, 8 is arranged on the input side of the peak amplifier 4 Variable phase shifter. Note that the variable attenuator 7 and the variable phase shifter 8 constitute a correction unit that corrects a passing phase amount and a gain of a high-frequency signal transmitted through the second path.

Next, the operation will be described. Carrier amplifier 3, peak amplifier 4, 1/4 wavelength line 5 and 1/4
Regarding the operation related to the wavelength line 6, the carrier amplifier 104, the peak amplifier 105, and the carrier amplifier 104 in the microwave Doherty amplifier illustrated in FIG.
The operation is the same as that of the 1/4 wavelength line 106 and the 1/4 wavelength line 103, and thus the description is omitted. In addition,
Similar to the conventional microwave Doherty amplifier, a quarter wavelength line 5 is provided to change the apparent load impedance of the carrier amplifier 3, but instead of the quarter wavelength line 5, 1/4 + n / A similar effect can be obtained by arranging a two-wavelength line (n is 0 or an arbitrary natural number).

Further, as described above, the gain and the passing phase amount are different between the carrier amplifier 3 and the peak amplifier 4 because the bias condition is largely different. Therefore, in the microwave Doherty amplifier according to the first embodiment,
The variable attenuator 7 and the variable phase shifter 8 are adjusted to compensate for the difference in gain between the carrier amplifier 3 and the peak amplifier 4 and the difference in the amount of passing phase. Thereby, it is possible to satisfactorily combine the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 at the output end.

As described above, according to the first embodiment, the variable attenuator 7 arranged on the input side of the peak amplifier 4
And the variable phase shifter 8 arranged on the input side of the peak amplifier 4, so that the difference in gain and the difference in passing phase between the carrier amplifier 3 and the peak amplifier 4 are compensated for, and Since the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 can be satisfactorily combined, the output power and efficiency of the entire microwave Doherty amplifier can be improved.

The variable attenuator 7 and the variable phase shifter 8 may be provided on the input side of the carrier amplifier 3.
The same effect as when provided on the input side of the peak amplifier 4 is achieved. FIG. 2 is a diagram showing a configuration of a modification of the microwave Doherty amplifier according to the first embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. Numeral 9 replaces the quarter-wavelength line 6 shown in FIG. 1 by delaying the phase of the high-frequency signal input to the second path by π / 4 with respect to the phase of the high-frequency signal input to the first path. Is a 90-degree distributor that distributes a high-frequency signal to two paths. By using such a configuration, the same operation and the same effect as the microwave Doherty amplifier shown in FIG. 1 can be achieved.

Embodiment 2 FIG. 3 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 2 of the present invention. 3, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 10 denotes a temperature sensor, 11 denotes a ROM (storage means) storing a set value related to control of the variable attenuator 7 and the variable phase shifter 8 as a function of temperature, and 12 denotes a ROM 11 based on the temperature measured by the temperature sensor 10. Variable attenuator 7
And a control circuit (control means) for reading a set value related to control of the variable phase shifter 8 and appropriately controlling the variable attenuator 7 and the variable phase shifter 8.

Next, the operation will be described. Temperature sensor 1
The ambient temperature is detected based on 0, and the set value related to the control of the variable attenuator 7 and the variable phase shifter 8 corresponding to the detected temperature is read from the ROM 11. The control circuit 12
The variable attenuator 7 and the variable phase shifter 8 are appropriately controlled according to the set value read from M11. The ROM 11 stores control data related to the variable attenuator 7 and the variable phase shifter 8 that are set to compensate for the difference in gain and the difference in the amount of passing phase between the carrier amplifier 3 and the peak amplifier 4 at each temperature. It is remembered.

As described above, since the bias conditions of the carrier amplifier 3 and the peak amplifier 4 are greatly different,
The form of characteristic change with temperature is also different. For example, as described in “Transistor Technology SPECIAL No. 1 Special Feature: All about Individual Semiconductor Device Utilization” on pages 130-131 or shown in FIG. ) Indicates that the temperature characteristics of the transconductance gm (generally, gm is proportional to the gain of the amplifier) are greatly different. When the gate voltage VGS is deep on the negative side, that is, under conditions close to class B or class C, when the temperature rises, the transconductance gm increases and the gain of the amplifier also increases. On the other hand, when the gate voltage is shallow on the minus side, that is, under conditions close to class AB, when the temperature rises, the transconductance gm decreases, and the gain of the amplifier decreases. As in the above example, in a Doherty amplifier using two amplifiers having greatly different bias conditions,
Differences in gain, passing phase amount, and the like occur between the two amplifiers due to temperature changes, and output combining at the output terminal is not performed well. Therefore, in the microwave Doherty amplifier according to the second embodiment, the variable attenuator 7 and the variable phase shifter 8 are appropriately controlled in accordance with the ambient temperature to obtain the difference between the gain of the carrier amplifier 3 and the peak amplifier 4 and the passing of the gain. Compensate for phase difference. Thereby, the carrier amplifier 3 at the output terminal
And the output power of the peak amplifier 4 can be favorably combined.

As described above, according to the second embodiment, the RO storing the set values related to the control of the temperature sensor 10 and the variable attenuator 7 and the variable phase shifter 8 as a function of the temperature is used.
A control circuit for reading the set values related to the control of the variable attenuator 7 and the variable phase shifter 8 from the ROM 11 based on M11 and the temperature measured by the temperature sensor 10 and controlling the variable attenuator 7 and the variable phase shifter 8 12, the variable attenuator 7 and the variable phase shifter 8 are appropriately controlled in accordance with the ambient temperature to compensate for the difference in gain between the carrier amplifier 3 and the peak amplifier 4 and the difference in the amount of passing phase. As a result, the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 at the output end can be satisfactorily combined, so that the microwave Doherty amplifier as a whole has high output power and efficiency regardless of the ambient temperature. This has the effect of being able to be maintained. For the data stored in the ROM, for example, the characteristic data of the amplifier with respect to the temperature as shown in FIG. 6 shown on page 131 of the above document is obtained in advance, and the data is changed so as to cancel the difference between the gain and the phase amount with respect to the temperature change. The set values for the attenuator 7 and the variable phase shifter 8 may be stored.

The variable attenuator 7 and the variable phase shifter 8 are provided on the input side of the carrier amplifier 3, and the control circuit 12 controls the variable attenuator 7 and the variable phase shifter 8 according to the ambient temperature.
And the same effect as in the case where the variable amplifier 7 and the variable phase shifter 8 are provided on the input side of the peak amplifier 4 can be obtained.

Embodiment 3 FIG. FIG. 4 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 3 of the present invention. 4, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 13 denotes a delay circuit that can adjust a passing phase amount of the high-frequency signal, that is, a delay time according to the frequency of the high-frequency signal to be transmitted. As the delay circuit, a general line such as a coaxial line or a delay filter utilizing the delay characteristics of a band-pass filter can be used.

Next, the operation will be described. Since the carrier amplifier 3 and the peak amplifier 4 have greatly different bias conditions, the amount of the passing phase, that is, the delay time differs according to the frequency. Therefore, in the microwave Doherty amplifier according to the third embodiment, the delay circuit 13 is provided, and the high-frequency signal transmitted through the first path in which the carrier amplifier 3 is disposed and the second circuit in which the peak amplifier 4 is disposed. By making the delay times related to the high-frequency signal transmitted through the path equal, the difference in the passing phase amount between the carrier amplifier 3 and the peak amplifier 4 is compensated according to the frequency of the high-frequency signal, and the carrier amplifier 3 And the output power of the peak amplifier 4 can be satisfactorily implemented over a wide band.

As described above, according to the third embodiment, since the delay circuit 13 capable of adjusting the delay time of the high-frequency signal to be transmitted is provided according to the frequency of the high-frequency signal to be transmitted, The delay time between the high-frequency signal transmitted through the first path and the high-frequency signal transmitted through the second path is matched to compensate for the difference in the amount of the passing phase between the carrier amplifier 3 and the peak amplifier 4, and the output terminal Since the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 can be satisfactorily combined over a wide band, there is an effect that a high-efficiency microwave Doherty amplifier can be obtained over a wide band.

The carrier amplifier 3 and the peak amplifier 4
The delay circuit 13 may be provided on the output side of the peak amplifier 4 according to the magnitude of the delay time according to the above.
3 may be provided, and in these cases, the same effect as above can be obtained.

The carrier amplifier 3 and the peak amplifier 4
Since the bias condition is greatly different from the above, the gain differs depending on the frequency. That is, the carrier amplifier 3 and the peak amplifier 4 have greatly different gain frequency characteristics. Therefore, a frequency equalizer that adjusts the gain of the high-frequency signal to be transmitted according to the frequency of the transmitted high-frequency signal may be provided instead of the delay circuit 13. Thus, the gain frequency characteristics of the high-frequency signal transmitted through the first path and the high-frequency signal transmitted through the second path can be matched, and good performance can be achieved over a wide band. . Of course, a configuration in which both the delay circuit and the frequency equalizer are provided may be adopted.

Embodiment 4 FIG. 5 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 4 of the present invention. 5, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and a description thereof will not be repeated. An AM-AM / PM adjuster 14 adjusts an AM-AM characteristic which is a relation between the input power and the output power of the peak amplifier 4 and an AM-PM characteristic which is a relation between the input power of the peak amplifier 4 and the amount of passing phase. It is.

Generally, the AM-AM / PM adjuster 14 can be constituted by a non-linear circuit. FIG. 6 shows AM-AM
It is a figure showing an example of composition of a / PM adjuster. In FIG. 6, 15 is an input terminal, 16 is a DC cut capacitor, 17 is a DC bias power supply, 18 is a bias resistor,
19 is a diode, and 20 is an output terminal. The AM-AM / PM regulator shown in FIG. 6 is an IEEE Transacti
on on Microwave Theoryand Techniques, vol.45, No.1
2, December 1997 ”, page 2431,
This is introduced as a nonlinear circuit using a diode configured to be used as a linearizer for compensating for nonlinearity (distortion) of an amplifier. In general, the AM-AM / PM adjuster can be configured by changing not only the circuit shown in FIG. 6 but also a circuit constant or the like of a circuit having a non-linear characteristic to a desired value.

FIG. 7 is a diagram showing another example of the configuration of the AM-AM / PM adjuster. 7, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, and a description thereof will not be repeated. 2
1 is a variable attenuator, 22 is a variable phase shifter, 23 is a divider that partially extracts the power of the high-frequency signal transmitted through the second path where the peak amplifier 4 is arranged, and 24 is the instantaneous power of the distributed signal. A level detector 25 for detecting the level is a control circuit for controlling the variable attenuator 21 and the variable phase shifter 22 according to the detected instantaneous power level. Level detector 24
Is controlled so as to generate a previously stored attenuation and phase shift for the high-frequency signal transmitted through the second path using the variable attenuator 21 and the variable phase shifter 22 in accordance with the input power level detected by By doing so, it is possible to adjust the AM-AM characteristics and the AM-PM characteristics.
That is, the variable attenuator 21, the variable phase shifter 22, the distributor 2
3. AM-A from level detector 24 and control circuit 25
An M / PM regulator can be configured.

FIG. 8 is a diagram showing another example of the configuration of the AM-AM / PM adjuster. 8, the same reference numerals as those in FIG. 7 denote the same or corresponding parts, and a description thereof will not be repeated. 2
Reference numeral 6 denotes a control circuit for controlling the bias condition of the peak amplifier 4 according to the instantaneous power level detected by the level detector 24. Since the gain and the passing phase amount of the peak amplifier 4 change according to the bias condition, the bias condition of the peak amplifier 4 is appropriately controlled according to the power level detected by the level detector 24 so that the peak amplifier 4 Such AM-AM characteristics and AM-PM characteristics can be adjusted. That is, the distributor 23, the level detector 24, and the control circuit 26 can constitute an AM-AM / PM adjuster.

Next, the operation will be described. When the instantaneous input power exceeds a certain value, the peak amplifier 4 is turned on to generate output power. However, in order to realize high efficiency and low distortion of the entire microwave Doherty amplifier, the peak amplifier 4 is required. It is necessary to optimize the value of the instantaneous input power at which the operation starts, and the characteristics related to the change of the instantaneous output power with respect to the change of the instantaneous input power, so-called AM-AM characteristics. Further, in order to properly combine the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 at the output end, a characteristic relating to a change in the passing phase amount with respect to a change in the instantaneous input power of the peak amplifier 4, that is, AM −P
It is necessary to optimize the M characteristics. Therefore, in the microwave Doherty amplifier according to the fourth embodiment, the AM
By providing the AM / PM adjuster, it is possible to optimize the characteristics relating to the change in the instantaneous output power and the change in the passing phase amount with respect to the change in the power level at which the peak amplifier 4 operates and the instantaneous input power. .

As described above, according to the fourth embodiment, the AM-AM characteristic, which is the relationship between the input power and the output power of the peak amplifier 4, and the relationship between the input power of the peak amplifier 4 and the passing phase amount. AM for adjusting certain AM-PM characteristics
-Since it is configured to include the AM / PM adjuster 14,
The AM-AM characteristic and the AM-PM characteristic of the peak amplifier 4 are optimized, and the output power of the carrier amplifier 3 and the output power of the peak amplifier 4 at the output end are satisfactorily combined, so that the entire microwave Doherty amplifier is obtained. There is an effect that high efficiency and low distortion can be realized.

The first and third embodiments described above.
Also, the fourth embodiment can be implemented individually, and the microwave Doherty amplifier can be configured by appropriately combining the features of the plurality of embodiments.

Embodiment 5 In the first to fourth embodiments, a high-frequency signal is input to an input terminal, and the high-frequency signal is distributed to two paths so that the carrier amplifier 3
The fifth embodiment is characterized in that a signal is distributed to two paths in a baseband section of a communication device. That is, the input baseband signal is distributed to two paths, that is, a first path in which the carrier amplifier 3 is disposed and a second path in which the peak amplifier 4 is disposed in a circuit portion for processing the baseband signal. Is what you do.

FIG. 9 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 5 of the present invention. In FIG. 9, the same reference numerals as those in FIG. 31 is a baseband signal input terminal, 32 is a baseband processing circuit that distributes the baseband signal to a first path and a second path, and performs processing on the baseband signal, and 33 transmits the first path. A frequency conversion circuit that converts the frequency of the baseband signal transmitted and the baseband signal transmitted through the second path, and outputs a high-frequency signal in each path. The frequency conversion circuit 33 includes a first frequency conversion mixer 34 disposed on the first path,
A second frequency conversion mixer 3 arranged on a second path
5. Local oscillator 36 for supplying carrier frequency signals to frequency conversion mixers 34 and 35, and 90-degree phase shifter 37
Is configured.

Next, the operation will be described. Input terminal 31
Is distributed to two paths in the baseband processing circuit 32 and then frequency-converted into a high-frequency signal in the frequency conversion circuit 33. The high-frequency signal frequency-converted in each path is
The signal is amplified by the carrier amplifier 3 and the peak amplifier 4, combined at the output terminal 2, and output.

In the baseband processing circuit 32 for processing the baseband signal, the baseband signal is distributed to two paths, so that a variable attenuator, a variable phase shifter, a delay circuit, an AM-AM / PM adjuster are provided. And the like can be configured for a lower frequency band relating to the baseband signal. For this reason, the degree of freedom relating to the configuration of the circuit for realizing the correction means is increased, and it is possible to create a circuit capable of performing adjustment more easily, a highly accurate circuit, and the like. That is, the baseband processing circuit 32 corrects one or both of the phase shift amount and the gain of the baseband signal transmitted on the first path or the baseband signal transmitted on the second path. , It is possible to realize easy adjustment and improvement in accuracy.

For example, FIG. 10 is a diagram showing a configuration of an AM-AM / PM adjuster for processing a baseband signal. The circuit shown in FIG. 10 is applied as it is to the baseband processing circuit 32 in FIG. FIG.
, 41 is a distributor for distributing the baseband signal to two paths, 42 is a level detector (level detecting means) for detecting the power level of the input baseband signal, 4
3 is a ROM in which control data corresponding to the power level is stored
(Storage means), 44 is a control circuit (control means) for controlling the amplitude and phase of the baseband signal according to the power level, and 45 is the control circuit for controlling the amplitude and phase of the baseband signal according to the control signal from the control circuit 44. A level / phase converter (conversion means) 46 for conversion is a first D / A converter for converting a baseband signal provided as a digital signal provided on a first path into an analog signal, and 47 a second D / A converter. This is a second D / A converter that is arranged on the path and converts a baseband signal provided as a digital signal into an analog signal. A first signal converting means for converting a baseband signal as a digital signal transmitted through the first path from the first D / A converter 46 and the first frequency conversion mixer 34 to an analog high-frequency signal. And the second D /
A second signal converter for converting a baseband signal as a digital signal transmitted through the second path from the A converter 47 and the second frequency conversion mixer 35 to an analog high-frequency signal is configured.

Next, the operation will be described. Control circuit 44
Reads out optimal control data from the ROM 43 according to the power level of the baseband signal detected by the level detector 42 and given as digital data, controls the level / phase converter 45 according to the control data, and Adjust the amplitude or phase of the signal. Since the above process is performed on a baseband signal having a lower frequency than the high-frequency signal, the degree of freedom of the adjustment is greater than when the amplitude and phase are adjusted in the high-frequency circuit,
It enables more accurate processing and, as a result, improves the efficiency of the microwave Doherty amplifier.

As described above, according to the fifth embodiment, a digital signal transmitted from the first path by the first D / A converter 46 and the first mixer 34 for frequency conversion is transmitted. A digital signal which is composed of a first signal converting means for converting a baseband signal into an analog high-frequency signal, a second D / A converter 47 and a second mixer 35 for frequency conversion is transmitted through a second path. And a second signal converting means for converting the baseband signal into an analog high-frequency signal, so that the amplitude, phase, and the like of the signal transmitted through the first path or the second path can be adjusted at a high frequency. Since it can be performed on a baseband signal whose frequency is lower than that of the signal, the degree of freedom of adjustment is increased, enabling more accurate processing, and improving the efficiency of the microwave Doherty amplifier. An effect that can be.

Further, since the adjustment operation relating to the amplifier can be performed by digital signal processing, the control-related data is transmitted to or received from a remote place, thereby monitoring the microwave Doherty amplifier from a remote place. And control can be made possible.

Further, a level detector 42 for detecting the power level of the input baseband signal, a ROM 43 storing control data corresponding to the power level, an amplitude / phase control of the baseband signal according to the power level And a level / phase converter 45 for converting the amplitude and phase of the baseband signal according to the control signal from the control circuit 44, so that the power level given as a digital signal It is possible to read out optimal control data from the ROM 43 in accordance with the data according to the above and execute the control operation related to the amplifier, so that it is possible to perform highly accurate processing and improve the efficiency of the microwave Doherty amplifier. It works.

Embodiment 6 FIG. FIG. 11 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 6 of the present invention. In the sixth embodiment as well, similar to the fifth embodiment, processing relating to amplitude, phase, and the like is performed on a baseband signal. In FIG. 11, the same reference numerals as those in FIGS. 9 and 10 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 51 denotes control data according to the power level and AM-AM related to the peak amplifier 4.
RAM (storage means) in which data on characteristics is stored,
52 is a distributor (distribution means) for extracting a part of the output power of the peak amplifier 4, 53 is a mixer for frequency conversion, and 54 is a digital converter for converting a baseband signal as an analog signal output from the mixer 53 for frequency conversion. A / to output
The D converter 55 is a base that is transmitted along a second path in which the peak amplifier 4 is arranged according to the power level detected by the level detector 42 and the baseband signal fed back from the A / D converter 54. This is a control circuit (control means) for controlling the amplitude and phase of the band signal. The frequency conversion mixer 53 and the A / D converter 54 constitute a signal inverting means for converting a high-frequency signal output from the distributor 52 into a baseband signal as a digital signal.

Next, the operation will be described. Input terminal 31
The baseband signal input from is distributed by the distributor 41 to a first path in which the carrier amplifier 3 is disposed and a second path in which the peak amplifier 4 is disposed. The control circuit 55 reads the corresponding control data from the RAM 51 according to the power level of the baseband signal detected by the level detector 42, and reads the level data according to the control data.
By controlling the phase converter 45, the amplitude and phase of the baseband signal are adjusted. In addition, the distributor 52 includes the peak amplifier 4
And extract a part of the output signal. Then, the extracted signal is frequency-converted by the frequency conversion mixer 53 and output as a baseband signal, and then is digitally converted by the A / D converter 54 and input to the control circuit 55. The control circuit 55 outputs the desired A stored in the RAM 51.
The control of the level / phase converter 45 is adjusted by comparing the M-AM / PM characteristic with the fed-back baseband signal. At this time, the control circuit 55
The data written in 51 is rewritten to optimal data. Providing the feedback function in this manner enables more accurate processing, and as a result, improves the efficiency of the microwave Doherty amplifier.

As described above, according to the sixth embodiment, the distributor 52 for extracting a part of the high-frequency signal output from the peak amplifier 4, the mixer 53 for frequency conversion and the A / D converter 54 Signal inversion means for converting the extracted high-frequency signal into a baseband signal as a digital signal, a level detector 42 for detecting the power level of the baseband signal transmitted through the second path, The RAM 51 in which the control data corresponding to the level and the data relating to the AM-AM / PM characteristics of the peak amplifier 4 are stored, the power level detected by the level detector 42 and the baseband signal fed back from the signal inversion means. Control circuit 5 for controlling the amplitude and phase of the baseband signal transmitted on the second path based on
5 and a level / phase converter 45 for converting the amplitude and phase of the baseband signal in accordance with the control signal from the control circuit 55, so that the output signal is digitally converted and fed back to the control circuit 55. Therefore, the A of the peak amplifier 4 stored in the RAM 51
It is possible to adjust the control of the level / phase converter 45 by comparing the data relating to the M-AM / PM characteristic and the fed-back signal, thereby realizing more accurate processing, and There is an effect that the efficiency of the Doherty amplifier can be improved.

Further, the control circuit 55 transmits the baseband signal fed back from the signal inversion means to the RAM 5.
1 is configured to rewrite the control data stored in the RAM 51 in comparison with the data related to the AM-AM / PM characteristics of the peak amplifier 4 stored in the peak amplifier 4. The control data can be set according to the characteristics, so that more accurate processing can be realized and the efficiency of the microwave Doherty amplifier can be improved.

Embodiment 7 FIG. 12 is a diagram showing a configuration of a microwave Doherty amplifier (Doherty amplifier) according to Embodiment 7 of the present invention. In FIG. 12, FIG.
The same reference numerals denote the same or corresponding parts, and a description thereof will not be repeated. 61 is an isolator (first isolator) arranged on the input side of the carrier amplifier 3, and 62 is an isolator (second isolator) arranged on the input side of the peak amplifier 4.

Next, the operation will be described. In a microwave Doherty amplifier, unlike an ordinary parallel amplifier, two amplifiers having different bias conditions are used, so that the balance between the two amplifiers is poor. Further, since a circuit path becomes longer due to the use of a quarter-wavelength line or the like, unnecessary loop oscillation occurs in a loop that goes around the path in which the carrier amplifier 3 is arranged and the path in which the peak amplifier 4 is arranged. Such a phenomenon is likely to occur. Therefore, in the microwave Doherty amplifier according to the seventh embodiment, the above-described loop oscillation is prevented by providing the isolators 61 and 62 on the input side of the carrier amplifier 3 and the peak amplifier 4.

As described above, according to the seventh embodiment, the isolator 61 provided on the input side of the carrier amplifier 3 and the isolator 62 provided on the input side of the peak amplifier 4 are provided. Therefore, there is an effect that a loop oscillation can be prevented and a microwave Doherty amplifier that operates stably can be obtained.

[0072]

As described above, according to the present invention, the input terminal and the first path extending from the input terminal are connected to the input terminal.
A first amplifier biased to class, class AB or class B, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed at an output side of the first amplifier in a first path; , Disposed on a second path extending from the input terminal,
A second amplifier biased to class C or class C, an output terminal arranged at a portion where the first path and the second path are coupled at the output side of the first amplifier and the second amplifier, A correction means for correcting either or both of the passing phase amount and the gain of the high-frequency signal transmitted through the first path or the high-frequency signal transmitted through the second path. One or both of the difference in gain and the difference in the amount of passing phase between the first and second amplifiers are compensated to improve the synthesis of the output power of the first amplifier and the output power of the second amplifier at the output terminal. Therefore, the output power and efficiency of the Doherty amplifier as a whole can be improved.

According to the present invention, the first means can be used as the correcting means.
A variable attenuator and a variable phase shifter disposed on the input side of the amplifier or the second amplifier, further comprising a temperature sensor;
Storage means for storing set values related to the control of the variable attenuator and the variable phase shifter as a function of temperature; and control of the variable attenuator and the variable phase shifter from the storage means based on the temperature measured by the temperature sensor. A control means for reading the set value and controlling the variable attenuator and the variable phase shifter is provided, so that the variable attenuator and the variable phase shifter are appropriately controlled in accordance with the ambient temperature to thereby control the first amplifier and the variable amplifier. Since the difference between the gain and the amount of the passing phase with respect to the second amplifier is compensated, the output power of the first amplifier and the output power of the second amplifier at the output terminal can be favorably combined. This has the effect that high output power and high efficiency can be maintained regardless of the ambient temperature as a whole Doherty amplifier.

According to the present invention, the first means is used as the correction means.
And the delay circuit arranged on the input side or the output side of the second amplifier or the second amplifier, so that the high-frequency signal transmitted through the path in which the first amplifier is arranged according to the frequency of the high-frequency signal The difference in the amount of the passing phase between the first amplifier and the second amplifier is compensated by matching the delay times of the high-frequency signal transmitted through the path in which the second amplifier is arranged, and the first terminal at the output terminal is compensated for. Since the output power of the amplifier and the output power of the second amplifier can be satisfactorily combined over a wide band, a high efficiency Doherty amplifier over a wide band can be obtained.

According to the present invention, the first means is used as the correction means.
Is configured to include a frequency equalizer disposed on the input side or the output side of the second amplifier or the second amplifier, so that the high-frequency signal transmitted through the path in which the first amplifier is disposed and the second amplifier are disposed. This makes it possible to make the frequency characteristics of the gain relating to the high-frequency signal transmitted through the route coincide with each other, and to achieve an excellent performance over a wide band.

According to the present invention, as the correction means, the second
AM-A which is the relationship between the input power and the output power of the amplifier
AM-AM / PM that adjusts the M characteristic and the AM-PM characteristic that is the relationship between the input power of the second amplifier and the amount of passing phase.
Since it is configured to include a regulator, the A of the second amplifier
The M-AM characteristics and the AM-PM characteristics are optimized, and the output power of the first amplifier and the output power of the second amplifier at the output end are combined to increase the efficiency of the entire Doherty amplifier and reduce distortion. This brings about an effect that realization can be realized.

According to the present invention, the input terminal, the first amplifier arranged in the first path extending from the input terminal and biased to class A, class AB, or class B, and the first amplifier in the first path. 1/4 + n / 2 arranged on the output side of the amplifier of
A wavelength line (n is 0 or an arbitrary natural number), a second amplifier arranged in a second path extending from the input terminal and biased in class B or C, and a first amplifier in the first path. A first signal conversion unit disposed on the input side for converting a baseband signal input from the input terminal into a high-frequency signal; and a second path disposed on the input side of the second amplifier and input from the input terminal. Signal converting means for converting the baseband signal into a high-frequency signal, and an output arranged at a portion where the first path and the second path are coupled on the output side of the first amplifier and the second amplifier. A terminal and correction means for correcting one or both of the amount of passing phase and the gain of the baseband signal transmitted through the first path or the baseband signal transmitted through the second path. Since form was first path or the second
The amplitude, phase, etc. of the signal transmitted through the path can be adjusted with respect to the baseband signal having a lower frequency than the high-frequency signal. This makes it possible to improve the efficiency of the Doherty amplifier.

According to the present invention, the first signal conversion means and the second signal conversion means are configured to convert a baseband signal provided as a digital signal into an analog high-frequency signal. Since the present invention can be implemented by digital signal processing, by transmitting control-related data to a remote place or receiving it from a remote place, it is possible to monitor and control the Doherty amplifier from a remote place. .

According to the present invention, the first means is used as the correction means.
Level detecting means for detecting the power level of the baseband signal transmitted through the second path or the second path; storage means for storing control data corresponding to the power level detected by the level detecting means; Since it is configured to include control means for controlling the amplitude and phase of the baseband signal according to the power level, and conversion means for converting the amplitude and phase of the baseband signal according to the control signal from the control means. Since the optimum control data can be read from the storage means in accordance with the data relating to the power level given as a digital signal and the control operation relating to the amplifier can be performed, the processing with high accuracy can be performed and the efficiency of the Doherty amplifier can be improved. Is achieved.

According to the present invention, the first means is used as the correction means.
Distributing means for extracting a part of the high-frequency signal transmitted through the first path or the second path; signal inverting means for converting the extracted high-frequency signal into a baseband signal as a digital signal; Level detecting means for detecting the power level of the baseband signal transmitted through the second path, control data corresponding to the power level detected by the level detecting means, and data relating to the characteristics of the first amplifier or the second amplifier And an amplitude of the baseband signal transmitted through the first path or the second path based on the power level detected by the level detection means and the baseband signal fed back from the signal inversion means. Control means for controlling one or both of the phase and the phase, and a baseband signal oscillation in response to a control signal from the control means. And since it is configured to include a conversion unit configured to convert either or both of the phases,
Since the output signal can be converted into a digital signal and fed back to the control means, the data relating to the characteristic of the first amplifier or the second amplifier stored in the storage means is compared with the baseband signal fed back. It is possible to adjust the control according to the means, and it is possible to realize a process with higher accuracy and to improve the efficiency of the Doherty amplifier.

According to the present invention, the control means comprises: a baseband signal fed back from the signal inversion means;
Since the control data stored in the storage means is rewritten in comparison with the data relating to the characteristics of the first amplifier or the second amplifier stored in the storage means, the Doherty-type amplifier actually used It is possible to set control data in accordance with the characteristics of (1), (2), (3), (3), (3), (3), (3), (3), (3), (3), (3), (3), (3), is achieved that the efficiency of the Doherty amplifier can be improved.

According to the present invention, the input terminal, the first amplifier arranged in the first path extending from the input terminal and biased to class A, class AB, or class B, and the first amplifier in the first path. 1/4 + n / 2 arranged on the output side of the amplifier of
A wavelength line (n is 0 or an arbitrary natural number), a second amplifier arranged in a second path extending from the input terminal and biased to class B or class C, and a first amplifier and a second amplifier. On the output side, an output terminal disposed at a portion where the first path and the second path are coupled, a first isolator disposed on an input side of the first amplifier, and an output terminal disposed on an input side of the second amplifier. Since the second isolator is provided, the loop oscillation can be prevented, and a Doherty amplifier that operates stably can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a microwave Doherty amplifier according to a first embodiment of the present invention;

FIG. 2 is a diagram illustrating a configuration of a modification of the microwave Doherty amplifier according to the first embodiment of the present invention;

FIG. 3 is a diagram illustrating a configuration of a microwave Doherty amplifier according to a second embodiment of the present invention;

FIG. 4 is a diagram illustrating a configuration of a microwave Doherty amplifier according to a third embodiment of the present invention;

FIG. 5 is a diagram showing a configuration of a microwave Doherty amplifier according to a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a configuration of an AM-AM / PM adjuster.

FIG. 7 is a diagram showing another example of the configuration of the AM-AM / PM adjuster.

FIG. 8 is a diagram showing another example of the configuration of the AM-AM / PM adjuster.

FIG. 9 is a diagram showing a configuration of a microwave Doherty amplifier according to a fifth embodiment of the present invention.

FIG. 10 is a diagram illustrating AM- for processing a baseband signal.
It is a figure showing composition of an AM / PM adjuster.

FIG. 11 is a diagram showing a configuration of a microwave Doherty amplifier according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a microwave Doherty amplifier according to a seventh embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of a waveform of a high-frequency signal.

FIG. 14 is a Smith chart showing the relationship between output-side load impedance, saturation power, and efficiency of an amplifying element such as an FET.

FIG. 15 is a diagram illustrating a configuration of a conventional microwave Doherty amplifier.

FIG. 16 is a diagram illustrating an operation state of the microwave Doherty amplifier when the power level of the input signal is low.

FIG. 17 is a diagram showing AM-AM characteristics of the Doherty amplifier.

FIG. 18 is a diagram illustrating a loop formed in the Doherty amplifier.

[Explanation of symbols]

1 input terminal, 2 output terminal, 3 carrier amplifier (first amplifier), 4 peak amplifier (second amplifier),
5,6 1/4 wavelength line, 7,21 variable attenuator, 8,
22 variable phase shifter, 10 temperature sensor, 11 ROM
(Memory means), 12, 44, 55 control circuit (control means), 13 delay circuit, 14 AM-AM / PM adjuster, 15 input terminal, 16 DC cut capacitor,
17 DC bias power supply, 18 Bias resistor, 19
Diode, 20 output terminals, 23 distributor, 24
Level detector, 25, 26 control circuit, 31 input terminal, 32 baseband processing circuit, 33 frequency conversion circuit, 34, 35, 53 frequency conversion mixer, 36 local oscillator, 37 90 degree phase shifter, 41 distributor, 4
2 level detector (level detection means), 43 ROM
(Storage means), 45 level / phase converter (conversion means), 46, 47 D / A converter, 51 RAM (storage means), 52 distributor (distribution means) 54 A / D converter, 61 isolator (No. 1 isolator), 62
Isolator (second isolator).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H03F 1/34 H03F 1/34 5J100 1/42 1/42 3/21 3/21 3/24 3/24 3/68 3/68 B H03G 3/30 H03G 3/30 B (72) Inventor Yukio Ikeda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Yuji Sakai Marunouchi, Chiyoda-ku, Tokyo 2-3-2 F-term in Mitsubishi Electric Corporation (reference) 5J069 AA01 AA26 AA41 CA02 CA21 CA36 CA54 CA62 FA01 FA10 FA19 HA09 HA19 HA25 HA29 HA32 HA43 KA00 KA15 KA16 KA23 KA32 KA34 KA68 KC04 KC06 MA11 TA01 TA02 TA05 TA06 5J090 AA01 AA26 AA41 CA02 CA21 CA01 FA02 HA19 HA25 HA29 HA32 HA43 KA00 KA15 KA16 KA23 KA32 KA34 KA68 MA11 TA01 TA02 TA05 TA06 5J091 AA01 AA26 AA4 1 CA02 CA21 CA36 CA54 CA62 FA01 FA10 FA19 HA09 HA19 HA25 HA29 HA32 HA43 KA00 KA15 KA16 KA23 KA32 KA34 KA68 MA11 TA01 TA02 TA05 TA06 5J092 AA01 AA26 AA41 CA02 CA21 CA36 CA54 CA62 FA01 FA10 FA19 GR09 HA09 KA23 HA25 KA32 KA34 KA68 MA11 TA01 TA02 TA05 TA06 5J100 JA01 KA05 LA00 LA11 QA01 QA02 SA01

Claims (12)

[Claims] An input terminal; a first path extending from the input terminal;
A class B or class B biased first amplifier, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed on the output side of the first amplifier in the first path, A second amplifier disposed in a second path extending from the input terminal and biased to class B or class C; and a first path at an output side of the first amplifier and the second amplifier. An output terminal arranged at a portion where the second path is coupled, a high-frequency signal transmitted through the first path or the second terminal;
And a correction means for correcting one or both of the passing phase amount and the gain of the high-frequency signal transmitted through the path. 2. The Doherty amplifier according to claim 1, further comprising a variable attenuator and a variable phase shifter arranged on the input side of the first amplifier or the second amplifier as the correction means. 3. A temperature sensor, storage means for storing a set value related to control of a variable attenuator and a variable phase shifter as a function of temperature, and a variable from the storage means based on the temperature measured by the temperature sensor. 3. The Doherty-type amplifier according to claim 2, further comprising control means for reading a set value related to control of the attenuator and the variable phase shifter to control the variable attenuator and the variable phase shifter. 4. The Doherty amplifier according to claim 1, further comprising a delay circuit disposed on an input side or an output side of the first amplifier or the second amplifier as the correction means. 5. The Doherty-type amplifier according to claim 1, further comprising a frequency equalizer arranged on an input side or an output side of the first amplifier or the second amplifier as the correction means. 6. An AM-AM characteristic which is a relation between an input power and an output power of a second amplifier, and
AM-, which is a relationship between the input power of the amplifier of FIG.
The Doherty amplifier according to claim 1, further comprising an AM-AM / PM adjuster for adjusting PM characteristics. 7. An input terminal, and a class A, A disposed in a first path extending from the input terminal.
A class B or class B biased first amplifier, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed on the output side of the first amplifier in the first path, A second amplifier disposed on a second path extending from the input terminal and biased to class B or C; and an input terminal disposed on an input side of the first amplifier in the first path, A first signal converting means for converting a baseband signal input from the input terminal into a high-frequency signal, and a baseband signal input from the input terminal, which is disposed on the input side of the second amplifier in the second path. Second signal conversion means for converting the signal into a high-frequency signal; and an output terminal disposed at a portion where the first path and the second path are coupled on the output side of the first amplifier and the second amplifier. And before Doherty comprising correction means for correcting one or both of a passing phase amount and a gain of a baseband signal transmitted through a first path or a baseband signal transmitted through the second path. Type amplifier. 8. The Doherty amplifier according to claim 7, wherein the first signal converter and the second signal converter convert a baseband signal provided as a digital signal into an analog high-frequency signal. 9. The first path or the second path as the correction means.
Level detecting means for detecting the power level of the baseband signal transmitted through the path, storage means for storing control data corresponding to the power level detected by the level detecting means, Control means for controlling either one or both of the amplitude and the phase of the baseband signal, and converting one or both of the amplitude and the phase of the baseband signal in accordance with the control signal from the control means 9. The Doherty amplifier according to claim 8, further comprising means. 10. A distributing means for extracting a part of a high-frequency signal transmitted through the first path or the second path as a correction means, and a signal for converting the extracted high-frequency signal into a baseband signal as a digital signal Inverting means;
Level detecting means for detecting the power level of the baseband signal transmitted through the second path or the second path, control data corresponding to the power level detected by the level detecting means, and the first amplifier or the second amplifier And a first path or a second path based on a power level detected by the level detecting means and a baseband signal fed back from the signal inverting means. Control means for controlling one or both of the amplitude and the phase of the baseband signal transmitted therethrough, and converting one or both of the amplitude and the phase of the baseband signal in accordance with the control signal from the control means The Doherty amplifier according to claim 7, further comprising a conversion unit. 11. The storage unit compares the baseband signal fed back from the signal inversion unit with data on characteristics of the first amplifier or the second amplifier stored in the storage unit. The Doherty amplifier according to claim 10, wherein the control data stored in the means is rewritten. 12. An input terminal, wherein the input terminal is disposed in a first path extending from the input terminal,
A class B or class B biased first amplifier, a 1/4 + n / 2 wavelength line (n is 0 or any natural number) disposed on the output side of the first amplifier in the first path, A second amplifier disposed in a second path extending from the input terminal and biased to class B or class C; and a first path at an output side of the first amplifier and the second amplifier. An output terminal arranged at a portion where the second path is coupled; a first isolator arranged at an input side of the first amplifier; a second isolator arranged at an input side of the second amplifier; A Doherty-type amplifier, comprising: