JP2011009923A - Power supply circuit of envelope tracking power supply, power amplifier, and radio base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a power supply circuit element has a difficulty in achieving in a balance between a high voltage and a bandwidth due to a device characteristic, a distortion occurs in an output waveform, and efficiency deteriorates in a power amplifier of a high-speed radio system using a wide dynamic range and a wideband signal, e.g., an envelope tracking power supply used for a wideband base station power amplifier.SOLUTION: An envelope tracking power supply comprises a first voltage generating portion and a second voltage generating portion, The first voltage generating portion is used as a synthetic amplifier (Class-BD system) having a switching amplifier and an error amplifier. By limiting an input of the first voltage generating portion by an amplitude or a frequency, the specification of an element of the Class-BD system is greatly alleviated to achieve amplification with a low distortion and a high efficiency. Also, residual signals are amplified by the second voltage generating portion, and the outputs of the first voltage generating portion and the second voltage generating portion are synthesized to achieve amplification with a low distortion and a high efficiency for whole signals.

Description

  The present invention relates to an envelope tracking power supply circuit suitable for, for example, a broadband wireless base station, a power amplifier, and a base station apparatus.

In recent years, OFDM (Orthogonal Frequency Division Multiplexing) has become the mainstream as a digital modulation technology that supports high-speed wireless communication. Since the signal used in OFDM has a high PAPR (Peak to Average Power Ratio), a reduction in efficiency in the power amplifier becomes significant. Therefore, in a base station that operates constantly and consumes a large amount of power, improving the efficiency of the power amplifier is an urgent issue.
In recent years, EER (Envelope Elimination and Restoration) and ET (Envelope Tracking) using an envelope tracking power supply have attracted attention as high efficiency techniques. For example, Patent Document 1 discloses the principle of operation thereof. Yes. These systems enable high-efficiency signals with a wide dynamic range by dynamically controlling and tracking the main amplifier power supply voltage (drain voltage in the case of MOS (Metal Oxide Semiconductor)) according to the signal envelope. This is an amplification method.

  FIG. 14 shows a configuration example of the EER power amplifier, and FIG. 15 shows waveforms at each point in the power amplifier circuit. An input signal 600 shown in FIG. 14 is an input signal to the EER power amplifier. Reference numeral 611 denotes a limiter, which is a circuit that removes the envelope and extracts phase information by limiting the amplitude of the input signal 600. Reference numeral 602 denotes a phase signal output from the limiter 611. Reference numeral 612 denotes a delay unit that adjusts timings of an amplitude signal 605 and a phase signal 603 described later. Reference numeral 603 denotes a phase signal delayed by the delay unit 612. Reference numeral 613 denotes a main amplifier that receives the phase signal 603 and modulates the power supply voltage using an amplitude signal 605 described later. Reference numeral 617 denotes a load impedance of the drain power supply of the main amplifier 613. Reference numeral 606 denotes an RF signal (high frequency signal) output from the main amplifier 613. Reference numeral 614 denotes an amplitude detector that extracts an amplitude signal. Reference numeral 604 denotes an amplitude signal. Reference numeral 615 denotes an envelope tracking power supply, which amplifies the amplitude signal 604 and outputs an amplitude signal 605.

  The EER power amplifier and the ET power amplifier are realized by substantially the same configuration, and the difference between them will be briefly described as follows. In the EER power amplifier, since the input signal 603 to the main amplifier 613 is only the phase component of the envelope with a constant amplitude, the main amplifier 613 uses a high-efficiency saturated amplifier (class D, class E, etc.). be able to. The amplitude signal 604 is amplified by the envelope tracking power supply 615, the envelope waveform of the input signal 600 is reproduced, and supplied as the power supply voltage of the main amplifier 613.

  On the other hand, the ET power amplifier does not require the limiter 611 in the configuration of FIG. An input signal 603 to the main amplifier 613 is an RF signal (phase / amplitude modulation signal), and a linear amplifier (Class A, Class AB, Class B) is used as the main amplifier 613. The difference from the normal amplifier is that the power supply voltage of the linear amplifier 613 is modulated in accordance with the envelope of the input signal 600. Thereby, compared to the case where a fixed voltage is applied to the power supply voltage of the linear amplifier 613, the back-off is reduced, and the efficiency of the linear amplifier 613 can be increased.

The envelope tracking power supply 615 can be realized with the same configuration in both the EER power amplifier and the ET power amplifier. However, in the EER power amplifier, the amplitude component of the signal to be amplified is reproduced in the power supply voltage of the main amplifier 613. In addition, accuracy is required in waveform reproduction and timing adjustment of the phase signal 603 and the amplitude signal 605.
As described above, in any of the envelope tracking power supplies of the EER power amplifier and the ET power amplifier, it is necessary to faithfully amplify a broadband signal having a wide dynamic range with high efficiency. As a known envelope tracking power supply, for example, a class S amplifier using PWM (Pulse Width Modulation) described in Patent Document 2, a method disclosed in Non-Patent Document 1 and Patent Document 3 (hereinafter, referred to as “Pulse Width Modulation”) Class-BD method). Patent Document 4 discloses a combination system that outputs a fixed power source for a low voltage input signal and performs envelope tracking for a high voltage input signal.

US Pat. No. 6,256,482 JP 2009-016999 A JP 1998-242779 specification Japanese Patent Application Laid-Open No. 2005-20893

G. B. Yundt, “Series or Parallel-Connected Composite Amplifiers,” IEEE Transactions on Power Electronics, Vol PE-1, No. 1, January 1986, pp 48-54.

A class S amplifier as disclosed in Patent Document 2 is used as an envelope tracking power source for narrow band signals such as audio amplifiers and narrow band radios. The class S amplifier is a system in which an input envelope signal is compared with a triangular wave, pulse width modulation is performed, a class D amplifier is amplified with the PWM signal, and a desired output is obtained with a subsequent filter. When comparing an input envelope signal and a triangular wave, high speed operation of several to several tens of times is required for the input signal band, so application to a wideband system is not realistic.
On the other hand, in the Class-BD system, since the switching operation is performed at a frequency equal to or lower than the signal bandwidth of the envelope signal, the class D amplifier efficiency is maintained high. Further, distortion can be reduced by an error amplifier constituted by a voltage follower, and a filter used in the S class is not necessary. For this reason, in a broadband wireless system, the Class-BD system described in Non-Patent Document 1 and Patent Document 3 is more effective in terms of distortion and efficiency.

  A conventional example of an envelope tracking power supply (Class-BD system) described in Non-Patent Document 1 is shown in FIG. Details of the operation are described in Non-Patent Document 1. In FIG. 16, reference numeral 410 denotes a class-BD type envelope tracking power supply, 400 denotes an input terminal, 401 denotes an input signal to the envelope tracking power supply 410, and 402 denotes an output signal from the envelope tracking power supply 410. Reference numeral 403 denotes a signal that flows in or out from an error amplifier 411 described later via a sense resistor 412. An output signal 404 is output from the switching amplifier 414 via the inductor 415. An error amplifier 411 includes a class B transistor, an operational amplifier, and the like, and has a voltage follower configuration that operates to keep the input and output voltages the same. 412 is a sense resistor. Reference numeral 413 denotes a sense circuit that amplifies a potential difference between both ends of the sense resistor 412, and includes an instrumentation amplifier, a hysteresis comparator, and the like. Reference numeral 414 denotes a switching amplifier including a class D amplifier. Reference numeral 415 denotes an inductor. Reference numeral 409 denotes an output terminal of the envelope tracking power supply 410, which is connected to the power load 617 of the main amplifier 613 in FIG. In general, the error amplifier 411 has a wide band and low efficiency, and the switching amplifier has high efficiency but a narrow band.

  17A and 17B show the output waveform of the conventional envelope tracking power supply 410 and the switching output waveform of the switching amplifier 414. FIG. 17A shows a case where a low frequency signal (10 kHz) is input to the envelope tracking power supply 410, and FIG. 17B shows a case where a high frequency signal (1 MHz) is input. 17A and 17B, 421 and 423 are output waveforms of the envelope tracking power supply 410, and 422 and 424 are switching output waveforms of the switching amplifier 414.

  When a low frequency signal is input to the envelope tracking power supply 410, the switching amplifier 114 repeats switching at a higher speed than the input frequency, and outputs a rectangular signal 422. The rectangular signal 422 is smoothed by the inductor 415, and the original input signal waveform is reproduced at the output terminal 409, that is, the load resistor 617 in FIG. 14 (FIG. 17A). At that time, the error amplifier 411 compares the input signal 401 and the output signal 402 and injects a minute current into the output of the error amplifier 411 or extracts it from the output of the error amplifier 411 so as to compensate for the voltage difference between them. I'm in charge. Since the switching amplifier 414 only performs the ON / OFF operation of the transistor, very high efficiency can be obtained at a low input frequency. On the other hand, the efficiency of the error amplifier 411 is low, but since the output power is very small, the overall efficiency of the envelope tracking power supply 410 is not significantly affected.

  When a high-frequency signal is input to the envelope tracking power supply 410, the switching amplifier 414 and the inductor 415 convert the original input signal waveform 401 to the output terminal 409, that is, FIG. The load resistance 617 cannot be reproduced. In this case, the error amplifier 411 greatly contributes to reproducing the original input signal waveform 401 at the output terminal 409. At this time, the switching frequency of the switching amplifier 414 is the same as the frequency of the input signal 401, the switching amplifier 114 is mainly responsible for the DC component of the output signal 402, and the error amplifier 411 is responsible for the AC component of the output signal 402. Shows an operation (FIG. 17B).

For this reason, when a high frequency signal is input to the envelope tracking power supply 410, the switching amplifier 414 operates at a high frequency at the same frequency as the input signal, and the efficiency is significantly degraded. Furthermore, since the contribution of the low-efficiency error amplifier 111 increases, the overall efficiency of the envelope tracking power supply 410 decreases. The reason why the efficiency of the error amplifier 411 is low is that it corresponds to the high dynamic range of the input signal, and therefore, it is amplified with a large backoff at the time of average power output (FIG. 18). FIG. 18 is a diagram showing input / output characteristics of the error amplifier 411 in FIG. In FIG. 18, 431 is the waveform of the input signal 401, 432 and 436 are the average power, 433 is the peak power of the input signal 401, 434 is the output waveform of the error amplifier 411, 435 is the saturation power, 437 is the input / output of the error amplifier 411. It is a characteristic.
For example, when the efficiency in the Class-B operation of the error amplifier 411 is calculated from the simple theoretical formula (1), the theoretical efficiency is 24.8% in the case of 10 dB backoff.

η _b = η _max × (P _b / P _max ) ^1/2 (1)

here
P _b : Output at back-off, P _max : Maximum output η _b : Efficiency at back-off, η _max : Maximum efficiency

As described above, in the high frequency band, the efficiency of the switching amplifier 414 deteriorates, the error amplifier 411 operates at a low efficiency, and the contribution to the output signal of the error amplifier 411 also increases, so the envelope tracking power supply 410 as a whole As the efficiency becomes low.
A mode in which the switching amplifier 414 reproduces the waveform by switching at a higher speed than the input signal is referred to as a follow-up mode. A mode in which the switching amplifier 414 operates at the same frequency as the input signal and the contribution of the error amplifier 411 is large in waveform reproduction is called a non-following mode. FIG. 19A shows the relationship between the efficiency of the envelope tracking power supply 410 and the input frequency in each mode. FIG. 19B shows the relationship between the switching frequency of the switching amplifier 414 and the input frequency in each mode. 19A and 19B, f _trans indicates an input frequency at which the tracking mode and the non-tracking mode are switched, and f _sw indicates a switching frequency of the switching amplifier 414 in the tracking mode. The parameters f _trans and f _sw are both determined by various parameters (power supply voltage and inductance) of the input signal and the envelope tracking power supply.

There are at least the following two problems when a wideband signal having a wide dynamic range is amplified with high efficiency by such a Class-BD amplifier.
(1) When a Class-BD amplifier is used in a base station, the error amplifier 411 located at the input stage needs to have a high voltage (high withstand voltage) and wideband characteristics, but it is difficult to realize at present. .
(2) When a wide-band envelope signal is amplified, the overall efficiency is lowered due to the efficiency drop in the high frequency band.
Hereinafter, each problem will be described in detail.
The problem (1) will be described. Since the error amplifier 411 located at the input stage needs to output the input signal 401 without distortion, a specification corresponding to the input signal 401 is required. Currently, wideband wireless systems that are assumed include WiMAX (Worldwide Interoperability for Microwave Access), LTE (Long Term Evolution), LTE-Advanced, and the like, all of which require a bandwidth of 20 to 100 MHz. Furthermore, in a power amplifier for a base station, since a high output and high PAPR signal is used, the voltage of the power amplifier circuit also increases. That is, the error amplifier 411 is required to have a high voltage, a wide band characteristic, and high efficiency.
On the other hand, an error amplifier 411 (comprising an operational amplifier and a transistor) having a bandwidth of several tens of volts and several tens of MHz that can be used in a base station is not currently available. This is because, if a structure that realizes a high voltage (high withstand voltage) characteristic is adopted, the capacitance component increases in principle and the frequency characteristic deteriorates. That is, in a device such as a transistor, the voltage (withstand voltage) and the bandwidth are in a trade-off relationship, and it is difficult to realize both specifications in the error amplifier 411 for the base station.

The problem (2) will be described. FIG. 20 shows an envelope spectrum of IEEE 802.11a, which is an OFDM standard. The horizontal axis is frequency and the vertical axis is power. Although the envelope envelope of OFDM has a wide frequency distribution, the envelope power supply unit 410 shown in FIG. 16 significantly deteriorates in efficiency due to a high switching frequency in a high frequency band as shown in FIG. . Since the envelope of OFDM has most of the signal power in the vicinity of DC, the envelope power supply unit 410 shown in FIG. 16 can achieve a certain degree of efficiency. However, in order to obtain higher efficiency, the efficiency in the high frequency band can be obtained. Improvement is essential.
In Patent Document 4, in order to avoid gain degradation or distortion that occurs when an input signal is operated near 0 V, a low voltage is output at a fixed voltage, and envelope tracking is performed for a high voltage signal. Although a combination method of performing is disclosed, this method does not solve the above-described problem.

For the problem (1), since the voltage (withstand voltage) and the bandwidth are in a trade-off relationship, it is difficult to realize an error amplifier having a voltage of several tens V and a band characteristic of several tens of MHz. (A) An error amplifier having a high voltage and narrow band (several tens of volts and several MHz) characteristics, or (b) an error amplifier having a low voltage and wide band (several V and several tens of MHz) characteristics, It is feasible. Therefore, either the high-voltage and narrow-band or low-voltage and wide-band input signal is processed by the first voltage generator, which is a Class-BD amplifier circuit, and other input signals are Processing is performed by a second voltage generator suitable for the signal. As a result, a high-voltage and wide-band power amplifier can output a signal with less distortion, and can be operated from the viewpoint of the Radio Law that limits unwanted waves.
However, when the input signal is separated into the first and second voltage generators, or when the output signals from the first and second voltage generators are synthesized, waveform distortion may occur during the separation and synthesis. There is also a concern that the outputs of the first and second voltage generators flow into each other's outputs during synthesis, and a signal that should originally be output is not output. Therefore, a means for compensating or avoiding them is provided.

The above problem (2) is caused by the deterioration in efficiency due to the high-speed operation of the switching amplifier 414 and the contribution of the error amplifier 411 whose efficiency has decreased due to a large back-off. Therefore, it is a solution to prevent the Class-BD amplifier circuit from operating at high speed, to reduce back-off, and to reduce the contribution of the error amplifier 411.
Specifically, firstly, a configuration in which an input signal to the Class-BD type amplifier circuit is limited to a low frequency and the Class-BD type amplifier circuit is operated in the follow-up mode. As a result, the switching amplifier 414 operates at a low speed, and furthermore, the influence of the low-efficiency error amplifier 411 is almost eliminated, so that high efficiency is obtained as a whole.
Alternatively, secondly, a configuration in which the input signal is limited to a low voltage is conceivable. As a result, the size of the device to be used is reduced, so that parasitic capacitance, which is a cause of deterioration in efficiency at high frequencies, is reduced. Therefore, the switching amplifier 414 and the error amplifier 411 that are highly efficient in the high frequency band can be realized. Further, since the PAPR of the input signal becomes small, the power supply voltage in the error amplifier 411 can be set small, and high-efficiency operation with small back-off is possible. The second case is realized by adopting a configuration in which high instantaneous power is not input to the Class-BD type amplifier circuit.

Specifically, the present invention is realized by a power supply circuit having the following configuration.
A power supply circuit comprising a first voltage generator and a second voltage generator,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
Generating an output voltage obtained by amplifying an input signal of a predetermined frequency or less in the first voltage generator and generating an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generator; or The first voltage generator generates an output voltage obtained by amplifying an input signal having a predetermined amplitude or less, and the second voltage generator generates an output voltage corresponding to an input signal having an amplitude larger than the predetermined amplitude.
A power supply circuit characterized in that the output from the first voltage generator and the output from the second voltage generator are combined.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply circuit and power amplifier which are applicable to the broadband wireless system which enables high-speed transmission, and have the characteristic of high efficiency and a broadband can be provided.

The block diagram which shows the structural example of the envelope tracking power supply in 1st Example of this invention. The figure which shows the frequency dependence of the efficiency of the envelope tracking power supply in FIG. The output waveform of the switching amplifier in FIG. The figure which shows the frequency characteristic of the voltage gain of the envelope tracking power supply in FIG. The block diagram which shows the structural example of the envelope tracking power supply in 2nd Example of this invention. The figure which shows an example of the amplitude distribution of an OFDM envelope. The block diagram which shows the structural example of the envelope tracking power supply in 3rd Example of this invention. The block diagram which shows the structural example of the envelope tracking power supply in 4th Example of this invention. 9 is a signal waveform for explaining the operation of the threshold comparison unit shown in FIG. The flowchart for demonstrating operation | movement of the threshold value comparison part shown in FIG. The block diagram which shows the structural example of the voltage source of FIG. 8 which outputs the waveform of FIG.9 (d). The block diagram which shows the structural example of the voltage source of FIG. 8 which outputs the waveform of FIG.9 (e). The block diagram which shows the structural example of the envelope tracking power supply in 5th Example of this invention. The block diagram which shows the prior art example of an EER type amplifier. The waveform in the EER type amplifier of FIG. The block diagram which shows the prior art example of an envelope tracking power supply. The actual measurement result of the output waveform in FIG. The figure which shows the input-output characteristic of the error amplifier in FIG. The figure which shows the input frequency characteristic of the efficiency of the envelope tracking power supply in FIG. 16, and the input frequency characteristic of the switching frequency of a switching amplifier. The envelope spectrum of IEEE802.11a. The block diagram which shows the structural example of the wireless base station which uses the envelope tracking power supply of this invention.

INDUSTRIAL APPLICABILITY The present invention is useful in an envelope tracking power supply used in a power amplifier that has a wide dynamic range and a wide band of a wireless signal as the communication speed increases. The envelope tracking power supply to which the present invention is applied is a power amplifier that varies the power supply voltage of the final stage power amplifier according to the envelope of the radio signal, such as an EER (Envelope Elimination and Restoration) method or an ET (Envelope Tracking) method. Preferably applied. Further, when selecting the EER method or the ET method, it is preferable to select according to the target specification such as distortion and efficiency and the embodiment of the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings. Throughout all the embodiments, the same reference numerals are given to the same components, and the overlapping description will be omitted as appropriate.

(First embodiment)
First, the configuration of a radio base station using the envelope tracking power supply of the present invention will be described with reference to FIG. FIG. 21 is a block diagram showing a configuration example of a radio base station 800 that uses the envelope tracking power supply of the present invention, and is applied to the second to fifth embodiments described later in addition to the first embodiment. The base station 800 includes a baseband unit 801 that performs signal processing and control of the analog units 810 and 811, a control signal 825 that is output from the baseband unit 801, an analog unit 810 that performs amplification and frequency conversion of transmission / reception signals, 811 and antennas 841 and 842 for transmitting and receiving wireless radio waves.
The baseband unit 801 is a network interface unit 802 that is a connection unit with a network, a processor 803 that executes instructions, a memory 804 that stores programs and data, and various arithmetic processes such as modulation / demodulation processing and FFT (Fast Fourier Transform). It comprises signal processing units 805 and 806 for performing. The analog units 810 and 811 include an RF unit 820 and a front end unit 830.

When transmitting, the RF unit 820 converts the digital signal from the baseband unit 801 into an analog signal, performs frequency conversion (up-conversion) to a desired carrier frequency, and amplifies the transmission signal. In the front end unit 830, the transmission signal from the RF unit 820 is amplified to a desired output level by the power amplifier 831, passed through an isolator, a filter (not shown in the figure), a transmission / reception changeover switch 833, and the like, and then the antenna 842. Send from.
In the case of reception, the front end unit 830 amplifies the signal from the antenna 842 by the low noise amplifier 832 via the transmission / reception selector switch 833. The RF unit 820 frequency-converts (down-converts) the received signal from the front-end unit 830 into a baseband signal and AD-converts it into a digital signal (analog / digital conversion). The AD-converted received signal is demodulated in the baseband unit 801. In the configuration of FIG. 21, two systems of signal processing units, analog units, and antennas are described for MIMO (Multiple Input Multiple Output). However, if MIMO support is not required, one system may be used.

  Next, a first embodiment of the envelope tracking power supply according to the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration example of the envelope tracking power supply 211 in the first embodiment of the present invention. The envelope tracking power supply 211 includes an input terminal 100, an output terminal 109, a Class-BD synthesis amplifier 110, a Doherty power amplifier 120, and a low-pass filter 131 and a high-pass filter that divide the input signal 101 according to frequency. 132, the low-pass filter 133 and the high-pass filter 134 that synthesize the outputs of the synthesis amplifier 110 and the Doherty power amplifier 120 without interference with each other, and the phase and amplitude between the synthesis amplifier 110 and the Doherty power amplifier 120 are adjusted. A phase / amplitude adjustment unit 128 is provided.

The signal line from the input terminal 100 is branched into two and connected to one end of the low-pass filter 131 and one end of the high-pass filter 132. The other end of the low-pass filter 131 is connected to the input of the synthesis amplifier 110, that is, one input of the error amplifier 111. The other input of the error amplifier 111 is connected to the output of the error amplifier 111, and further connected to one end of the sense resistor 112 and one input of the sense circuit 113. The other input of the sense circuit 113 is connected to the other end of the sense resistor 112 and is further connected to the input of the low-pass filter 133. The output of the sense circuit 113 is connected to the input of the switching amplifier 114. The output of the switching amplifier 114 is connected to one end of the inductor 115, and the other end of the inductor 115 is connected to the other end of the sense resistor 112.
The other end of the high pass filter 132 is connected to the input of the phase / amplitude adjustment unit 128. The output of the phase / amplitude adjustment unit 128 is connected to the input of the Doherty power amplifier 120, that is, the input of the distributor 121. One of the outputs of the distributor 121 is connected to the input of the carrier amplifier 123. The output of the carrier amplifier 123 is connected to one end of the 90-degree phase shifter 125. The other end of the 90 degree phase shifter 125 is connected to one of the inputs of the combiner 122. The other of the outputs of the distributor 121 is connected to one end of the 90-degree phase shifter 126. The other end of the 90 degree phase shifter 126 is connected to the input of the peak amplifier 124. The output of the peak amplifier 124 is connected to the other input of the synthesizer 122. The output of synthesizer 122 is connected to the input of high pass filter 134. The output of the low-pass filter 133 and the output of the high-pass filter 134 are connected to the output terminal 109.

Of the input signal 101, the low-frequency signal 102 (including the DC component) filtered by the low-pass filter 131 is amplified by the synthesis amplifier 110. The high-frequency signal 103 filtered by the high-pass filter is amplified by the Doherty power amplifier 120. The output 106 of the synthesis amplifier 110 and the output 107 of the Doherty power amplifier 120 are added after passing through the filter 133 and the filter 134, respectively, and are output to the output terminal 109 as an output signal 108. Since the output terminal 109 is connected to the power supply load 617 of the main amplifier 613 of the EER type amplifier as shown in FIG. 14, the power supply voltage of the main amplifier 613 is modulated by the output signal 108. The terms “low frequency” and “high frequency”, or “small amplitude” and “large amplitude” used here represent relative meanings in the input signal 101, and are used in the same meaning below.
Note that the output of the input terminal 100 is branched before the low-pass filter 131 and the high-pass filter 132, but a simple connection or a distributor may be used for the branch. Similarly, the output of the low-pass filter 133 and the high-pass filter 134 at the output terminal 109 may be a simple connection or a synthesizer.
The low-pass filter 131, the high-pass filter 132, and the phase / amplitude adjustment unit 128 may realize the same function by digital signal processing such as a DSP (Digital Signal Processor) or may be realized by an analog element. .

  The synthesis amplifier 110 includes a wide band and relatively low-efficiency error amplifier 111, a sense resistor 112, a sense circuit 113, a narrow band and high-efficiency switching amplifier 114, and an inductor 115. Of the input signal 101, wideband signal components that cannot be processed by the switching amplifier 114 and noise generated by the switching amplifier 114 are canceled out by the output of the error amplifier 111, thereby realizing a power supply circuit with high efficiency and low noise. . The switching amplifier 114 includes an upper MOS (High Side MOS) 181 and a lower MOS (Low Side MOS) 182 that perform a switching operation, and a penetration prevention logic unit 180 that prevents the upper MOS 181 and the lower MOS 182 from being turned on simultaneously. Etc. The reason why the synthesis amplifier of this system is called the Class-BD system is that the error amplifier 111 is often configured as a class B power amplifier, and the switching amplifier 114 is a class D power amplifier. To do.

  The operation of the synthesis amplifier 110 will be briefly described below. Here, in order to simplify the description, a case where a DC signal is input will be described. When a DC signal is input from the input terminal 100, the error amplifier 111 that forms a voltage follower passes a current to the output terminal so that the input DC level is equal to the output DC level. The error amplifier 111 causes the current to flow out from or flow into the output terminal so that the same voltage as the input signal to the input terminal is generated at the output terminal of the error amplifier 111. At that time, when a current starts to flow through the sense resistor 112 and the potential generated at the sense resistor 112 exceeds the threshold value of the sense circuit unit 113 including a hysteresis comparator, the High Side MOS 181 of the switching amplifier 114 is turned on. To do. As a result, the switching amplifier 114 supplies a current to the output 106 of the synthesis amplifier 110. The current at the output 106 of the synthesis amplifier 110 is the sum of the current from the error amplifier 111 and the current from the switching amplifier 114. As the current from the switching amplifier 114 continues to increase, the current from the error amplifier 111 decreases, and as a result, the potential generated at the sense resistor 112 decreases. When the potential generated in the sense resistor 112 is lowered to a certain potential, the threshold value of the sense circuit 113 is exceeded, and the high side MOS 181 of the switching amplifier 114 is turned off (low side MOS 182 is turned on). As a result, the current supply from the switching amplifier 114 to the output 106 is reduced, and the error amplifier 111 starts to pass a current again through its output terminal. By repeating the above operation, the synthesis amplifier 110 generates a desired output signal.

The operation of the Doherty power amplifier 120 will be briefly described below. The Doherty power amplifier 120 includes two amplifiers called a carrier amplifier 123 and a peak amplifier 124, 90-degree phase shifters 125 and 126 that generate a 90-degree phase difference at a desired frequency, a distributor 121, and a combiner. A device 122 is provided. Note that the 90-degree phase shifter 125 and the combiner 122, and the 90-degree phase shifter 126 and the distributor 121 may each be configured by one element such as a wideband transformer as long as the desired operation is satisfied. The carrier amplifier 123 is an amplifier biased to any of class A, class AB, or class B, and the peak amplifier 124 is a class C biased amplifier so as to amplify only a large amplitude signal. .
The signal input from the input terminal of the Doherty power amplifier 120 is divided by the distributor 121, and then one is input to the carrier amplifier 123. The other is rotated 90 degrees by a 90-degree phase shifter 126 and input to the peak amplifier 124. A 90-degree phase shifter 125 is provided on the output side of the carrier amplifier 123. The output signal from the carrier amplifier 123 is rotated by 90 degrees by the 90-degree phase shifter 125 and then combined with the output of the peak amplifier 124 by the combiner 122.

When the instantaneous input power to the Doherty type power amplifier 120 is small, the carrier amplifier 123 amplifies and outputs the input signal, but the peak amplifier 124 is not operated in the off state because it is C-class biased. At this time, the power consumption of the peak amplifier 124 is sufficiently small, and the carrier amplifier 123 adjusted so as to obtain high efficiency at low output can obtain high power efficiency.
On the other hand, when the instantaneous input power to the Doherty power amplifier 120 is large, the peak amplifier 124 also operates and is combined with the output of the carrier amplifier 123 and output. In the Doherty-type power amplifier, by using a 90-degree phase shifter, the impedance that appears to be a load varies depending on the operation mode, which contributes to higher efficiency.

In the parallel configuration amplifier of the synthesis amplifier 110 and the Doherty amplifier 120 in FIG. 1, the input signal is limited so that each amplifier operates in a frequency band in which each is good, thereby realizing high efficiency of the envelope tracking power supply 211 as a whole. . That is, a low frequency signal is input to the synthesis amplifier 110 capable of high-efficiency operation from a direct current to a low frequency signal by the low pass filter 131, and a signal having a higher frequency than the signal input to the synthesis amplifier 110 is a high pass signal. The signal is input to the Doherty amplifier 120 by the filter 132 and amplified. An output signal 108 is output by adding the output signals.
By adopting this configuration, the specification of the error amplifier 111 can be relaxed from the high voltage and wide band, which has been a conventional problem, to the high voltage and narrow band, and the input signal is amplified while suppressing distortion. It becomes possible. Furthermore, since the input signal band is limited by the low-pass filter 131, the switching amplifier 114 does not operate at a high frequency and is limited to an operation in a high-efficiency region in a low frequency band. On the other hand, since the high-frequency signal can be amplified with high efficiency by the Doherty power amplifier 120, the above-described parallel configuration amplifier can be amplified with high efficiency over the entire band as a result.

FIG. 2 shows an example of the efficiency improvement effect according to this embodiment. FIG. 2 is a diagram showing the frequency dependence of the efficiency of the envelope tracking power supply 211 of FIG. In FIG. 2, the efficiency 201 of the synthesis amplifier 110 is as high as 95% because the switching amplifier 114 is mainly responsible for signal amplification in the low frequency band (DC to f1 in this example). When the frequency becomes higher than f1, the non-following mode is entered, and the efficiency 201 of the synthesis amplifier 110 decreases due to the influence of the switching amplifier 114 operating at a high frequency and the contribution to the overall output of the low-efficiency error amplifier 111 increasing. Begin to.
On the other hand, the efficiency 202 of the Doherty power amplifier 120 is constant regardless of the frequency in the example of FIG. 2, and the efficiency 202 of the Doherty power amplifier 120 is higher than the efficiency 201 of the synthesis amplifier 110 at the frequency f2 or higher. growing. Therefore, a frequency (f2 in FIG. 2) at which the efficiency 201 of the synthesis amplifier 110 and the efficiency 202 of the Doherty power amplifier 120 are approximately the same is set as a transition frequency for switching between these operations. Further, based on this transition frequency, the pass band of the low-pass filter 131 and the high-pass filter 132, the operation band of the Doherty power amplifier 120, and the like are set. In the above, the transition frequency is set based on the efficiency, but it may be designed in consideration of parameters such as distortion.
In the example of FIG. 2, the efficiency 203 of the envelope tracking power supply 211 shows 95% by the efficiency 201 of the synthesis amplifier 110 below the frequency f1, and 95 to 95 by the efficiency 201 of the synthesis amplifier 110 at the frequencies f1 to f2. 50% is shown, and at frequency f2 or higher, 50% is shown by the efficiency 202 of the Doherty power amplification (120).

Further, in the case of the present embodiment, a low-pass filter 133 is mounted on the output 106 of the synthesis amplifier 110 and a high-pass filter 134 is mounted on the output 107 of the Doherty power amplifier 120, so that the respective output signals do not flow into each other. The desired signal can be transmitted to the output terminal 109. This avoids the problem of discontinuity of the output signal due to switching, as compared with a method of switching the output 106 and the output 107 using a switch or the like.
In particular, when the low-pass filter 133 and the high-pass filter 134 as shown in FIG. 1 are mounted, the following effects are also expected. FIG. 3 shows an actual measurement result of the output waveform of the switching amplifier 114. As shown in FIG. 3, spikes and high-frequency ringing (in this example, about 100 MHz) are observed in the output waveform of the switching amplifier 114. These spikes and ringing cause distortion in the output waveform of the envelope tracking power supply 211. In the present embodiment, high-frequency distortion components (spikes, ringing, etc. generated during switching) generated by the synthesis amplifier 110 are attenuated by the low-pass filter 133, so that the output 108 of the envelope tracking power supply 211 is low. It becomes distortion.

In this embodiment, the output of the synthesis amplifier 110 and the output of the Doherty amplifier 120 are synthesized to generate the output signal 108. Therefore, it is preferable to determine various specifications such as the gain of the synthesis amplifier 110 and the Doherty amplifier 120 and the delay element in consideration of the amplitude characteristic and phase characteristic of the synthesized output signal 108. A specific example of the amplitude characteristic will be described below with reference to FIG. FIG. 4 is a diagram showing frequency characteristics of voltage gain of the envelope tracking power supply 211 in FIG. In FIG. 4, reference numeral 500 denotes frequency characteristics of voltage gain of the synthesis amplifier 110, and reference numerals 501 to 503 denote frequency characteristics of voltage gain of the Doherty power amplifier 120. Reference numerals 504 to 506 denote voltage gain frequency characteristics obtained by combining 500 and 501, 500 and 502, and 500 and 503, respectively. The combined gain in the envelope tracking power supply 211 preferably has a characteristic such as 505 having no frequency dependency. However, for example, when the envelope tracking power supply unit 211 of this embodiment is used in place of the conventional envelope tracking power supply 615 in the EER amplifier as shown in FIG. 14, the frequency characteristic of the gain of the main amplifier 613 is 505. If the frequency characteristic of the main amplifier 613 is not flat, the frequency characteristic of the voltage gain of the envelope tracking power supply unit 211 cancels out the frequency characteristic of the voltage gain of the main amplifier 613 so that the output 606 of the main amplifier 613 does not have frequency dependence. Alternatively, the combined gain of the envelope tracking power supply 211 may be set.
In FIG. 1, the Doherty power amplifier 120 is used as the second voltage generator. However, the present invention is not limited to this, and a configuration such as a fixed power source may be used instead.

Hereinafter, configurations applicable to both the present embodiment and the second to fifth embodiments described later will be described.
As implemented by predistortion or the like, the frequency characteristics of the envelope power supply unit 615 and the main amplifier 613 shown in FIG. 14 are measured in advance, and the frequency characteristics of the input signal are canceled by the frequency characteristics of the main amplifier 613. An input signal in which the frequency characteristics are set so that the frequency characteristics of the amplitude and the phase frequency characteristics at the output 606 of the output 606 are flat, that is, an input signal that eliminates distortion in the amplifier output is defined as the input signal 101 in FIG. You may make it input.
In addition, a waveform that takes into account the effects of distribution, amplification, and synthesis of the synthesis amplifier 110 and the Doherty power amplifier 120 may be input as the input signal 101.

  Further, a part of the output signal 606 of the main amplifier 613 is taken out and monitored by a directional coupler or the like, and the baseband unit 801 in FIG. 21 controls the analog unit 811 so that the output signal 606 is linearly output. You may make it correct | amend dynamically so that it may be carried out. Specifically, an input signal 101 that captures characteristic variations (gain, phase change, etc.) of various elements (such as power amplifiers and analog components) caused by temperature changes and aging changes, and compensates for the fluctuations is used as a base. It can be considered that the band unit 801 generates and outputs it. In the case of dynamic control, since it is possible to correct parameters that are difficult to measure in advance (such as temperature changes), it is possible to adjust more precisely and to obtain an output signal 606 with less distortion.

Further, the phase / amplitude adjustment unit 128 may set a fixed value in advance, or, like the predistortion, takes out a part of the signal of the output signal 108 with a directional coupler or the like, and baseband unit 801. Therefore, more accurate adjustment is possible by applying feedback control. For example, when the baseband unit 801 determines that the distortion of the output signal 108 increases due to the decrease in the gain of the Doherty power amplifier 120, the baseband unit 801 determines that the phase / amplitude adjustment unit is based on the determination. 128 can be adjusted to balance the phase and amplification degree of the synthesis amplifier 110 and the Doherty power amplifier 120. Although an example in which control is performed by the baseband unit 801 has been described above, a simple control circuit including a logic (logic operation unit), a comparator, a table, and the like may be mounted on the power amplifier 831.
In addition, by controlling the voltage applied to the constituent elements of the envelope tracking power supply unit according to the baseband signal and the input signal 101, control of distortion generated in the flow of division, amplification, and synthesis, and improvement in efficiency It is also possible to do. More specifically, the power supply voltage of the error amplifier 111 and the switching amplifier 114 is changed in accordance with the input signal 101. Thereby, in the error amplifier 111, since the back-off with respect to an input signal becomes small, efficiency is improved. Also in the switching amplifier 114, the duty can be kept close to 50%, so that the offset current between the input and output is reduced and the efficiency is improved. As a result, the efficiency of the entire power supply unit is improved. Further, similarly to the above, by performing feedback control based on the output signal 108, it becomes possible to cope with temperature change and aging change, and efficiency and distortion are improved. In particular, for a power amplifier, it is possible to control the distortion characteristics, gain, efficiency, etc. by changing the operating point by controlling the bias voltage and current.

(Second embodiment)
Next, a second embodiment of the envelope tracking power supply according to the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration example of the envelope tracking power supply 212 in the second embodiment of the present invention. The envelope tracking power supply 212 includes an input terminal 100, an output terminal 109, a synthesis amplifier 110, a limiter 169, a phase / amplitude adjustment unit 128, a class-C biased amplifier 150, and isolators 161 and 162. Yes.
The signal line from the input terminal 100 is branched into two, one connected to the input of the limiter 169 and the other connected to the input of the phase / amplitude adjustment unit 128. The output of the limiter 169 is connected to the input of the synthesis amplifier 110. The circuits in the synthesis amplifier 110 are connected in the same manner as in the embodiment of FIG. The output of the synthesis amplifier 110, that is, one input of the sense circuit 113, the other end of the sense resistor 112, and the other end of the inductor 115 are connected to the input of the isolator 161. The output of the phase / amplitude adjustment unit 128 is connected to the input of the class C amplifier 150. The output of the class C amplifier 150 is connected to the input of the isolator 162. The outputs of the isolators 161 and 162 are connected to the output terminal 109.

Note that the signal line from the input terminal 100 is branched into two and connected to the limiter 169 and the phase / amplitude adjustment unit 128. However, as shown in FIG. It is also possible to adopt a configuration such as a distributor. The same applies to the output terminal 109. The outputs of the isolators 161 and 162 may be wired or may be composed of a synthesizer or the like. Further, as in the embodiment of FIG. 8 described later, the connection may be made using a switch.
Since the input signal 101 is limited by the limiter 169, only a small amplitude signal is input to the synthesis amplifier 110, and the synthesis amplifier 110 is realized by a circuit configuration with a low voltage and a wide bandwidth.
On the other hand, the large-amplitude peak signal 163 is amplified by the class-C biased power amplifier 150 to become a peak signal 167. The peak signal 167 is added to the output 106 from the synthesis amplifier 110 and output from the output terminal 109 as the output signal 108. At this time, the isolators 161 and 162 are configured so that the output from the synthesis amplifier 110 is output to the output of the class C amplifier 150, or the output of the class C amplifier 150 is output to the output terminal 109 without flowing into the synthesis amplifier 110. Are arranged at the output of the synthesis amplifier 110 and the output of the class C amplifier 150, respectively. An isolator transmits signals from the primary side (input side) to the secondary side (output side) but does not transmit signals from the secondary side (output side) to the primary side (input side). It is an element with. When the envelope tracking power supply 212 of this embodiment is applied to a WiMAX radio base station, sufficient isolation is required in the bandwidth (about DC to 20 MHz) amplified by the envelope tracking power supply 212.

  Next, setting conditions of the limiter 169 will be described. FIG. 6 shows an envelope amplitude distribution in IEEE802.11a. In FIG. 6, the horizontal axis is the normalized voltage (amplitude) when the maximum instantaneous voltage (peak voltage) is 1, and the vertical axis is the distribution density. As described above, the OFDM envelope signal has a high PAPR but is distributed in the vicinity of the average voltage. For example, the ratio of envelope signals that fall within the range of normalized voltages 0 to 0.6 occupies 96%. In the present embodiment, for example, the limit value of the limiter 169 is set with a standardized voltage of 0.6, and the input to the synthesis amplifier 110 is limited. As a result, since the synthesis amplifier 110 operates at a low voltage, the low-voltage and wide-band error amplifier 111 can be used. Thus, since the error amplifier 111 and the switching amplifier 114 can be low voltage devices, a device with good high frequency characteristics can be used, and the efficiency of the synthesis amplifier 110 in the high frequency band is improved. The limit value of the limiter 169 is set to the standardized voltage 0.6 in the above example, but it depends on the voltage distribution of the input signal and the parameters such as the efficiency and distortion of the synthesis amplifier 110, the class C amplifier 150 and other elements. Is set.

In the envelope tracking power supply 212 of this configuration, when the instantaneous voltage of the input signal is small, only the synthesis amplifier 110 operates and the class C amplifier 150 does not operate. When the instantaneous voltage of the input signal is large, both amplifiers 110 and 150 are operated, and a second state in which the added output signal 108 is output to the output terminal 109 is obtained. At this time, the limit value of the limiter 169 and the bias condition of the class C amplifier 150 (the input voltage at which the class C amplifier starts amplification) are smoothly changed from the first state to the second state. Set. For example, in the above example, if the setting is such that an input signal smaller than the standardized voltage 0.6 is input to the synthesis amplifier 110, the class C amplifier 150 causes the remaining signal, that is, the standardized voltage 0.6. It is set to amplify a signal of .about.1.0. As a result, the class C amplifier 150 has a bias setting such that the output signal 108 is synthesized without distortion at the output terminal 109. In addition, the gain of the transition state in both amplifiers (the transition state between the first state in which only the composite amplifier is moving and the second state in which both of them start to move), and the respective gains of the first state and the second state It is also possible to generate a signal in consideration of the above with a predistorter and input it to the envelope tracking power supply 212.
In this embodiment, it is possible to achieve the objectives such as relaxation of the specification of the error amplifier 111 and high efficiency of the envelope tracking power supply 212 with a very simple configuration. Furthermore, since the outputs of the synthesis amplifier 110 and the class C amplifier 150 are not switched by a switch, the discontinuity of the output signal 108 output to the output terminal 109 does not occur.

(Third embodiment)
Next, a third embodiment of the envelope tracking power supply according to the present invention will be described with reference to FIG. FIG. 7 is a block diagram showing a configuration example of the envelope tracking power supply 213 in the second embodiment of the present invention. In FIG. 7, the envelope tracking power supply 213 in the third embodiment includes an input terminal 100, an output terminal 109, a phase / amplitude adjustment unit 128, synthesis amplifiers 190 and 200, a distributor 191 and a combiner 192. It has. 7 are the same as the constituent elements of the synthetic amplifier 110 in FIG. 1, the constituent elements of the synthetic amplifier 190 are numbered according to FIG. 1, such as the error amplifier 111A, the switching amplifier 114A, and the like. The numbers of the constituent elements of the synthesis amplifier 200 are set as the error amplifier 111B, the switching amplifier 114B, and the like.

  A signal line from the input terminal 100 is connected to the distributor 191. One output of the distributor 191 is connected to the input of the synthesis amplifier 190. The other output of the distributor 191 is connected to the input of the phase / amplitude adjustment unit 128. The output of the phase / amplitude adjustment unit 128 is connected to the input of the synthesis amplifier 200. The circuits in the synthesis amplifiers 190 and 200 are connected in the same manner as in the embodiment of FIG. The output of the synthesis amplifier 190 is connected to one input of the synthesizer 192, and the output of the synthesis amplifier 200 is connected to the other input of the synthesizer 192. The output of the combiner 192 is connected to the output terminal 109.

In this embodiment, the input signal 101 is called a low-frequency filter (not shown) or a digital signal processing in the baseband unit 801 and is called a DC component and a low-frequency signal (low frequency compared to the envelope band). Signal processing is performed in the preceding stage of the input terminal 100 so that the meaning) is input.
The specifications of the synthesis amplifiers 190 and 200 are different. For example, the synthesis amplifier 190 has a high voltage and narrow band configuration, and the synthesis amplifier 200 has a low voltage and wide band configuration. As a result, the specifications of each synthesis amplifier, particularly the specifications of the error amplifiers 111A and 111B, are relaxed, and a signal with small distortion can be output with high efficiency over the entire input signal.

Further, the distributor 191 and the combiner 192 are replaced with switches as shown in FIG. 8 to be described later, and the combined amplifiers are controlled by the control signal based on the input signal 101 so that the combined amplifiers 190 and 200 operate in an excellent operation region. By switching the input signal, the input signal may be input only to one appropriate synthesis amplifier. For example, as described above, when the synthesis amplifier 190 has a high voltage and narrow band configuration and the synthesis amplifier 200 has a low voltage and wide band configuration, a large amplitude (high voltage) and narrow band signal is generated. When input, the input terminal 100 and the input of the synthesis amplifier 190 are connected, and the output of the synthesis amplifier 190 and the output terminal 109 are connected. When a small amplitude (low voltage) and wideband signal is input, the input terminal 100 and the input of the synthesis amplifier 200 are connected, and the output of the synthesis amplifier 200 and the output terminal 109 are connected. The error amplifier 111A of the synthesis amplifier 190 is set to have a high power supply voltage. However, since a signal with a large amplitude (high voltage) is input, the back-off is small and operates with high efficiency. As a result, the synthesis amplifier 190 also operates with high efficiency. Similarly, since the input signal to the synthesis amplifier 200 is limited to one having a small amplitude, the error amplifier 111B set to a low power supply voltage also operates with high efficiency, and the synthesis amplifier 200 also operates with high efficiency. As a result, high efficiency is realized in the entire envelope tracking power supply 213. In addition, since the input signal is appropriate in each synthesis amplifier, the occurrence of distortion can be suppressed.
Although not shown in FIG. 7, when there is a concern that the output of the synthesis amplifier 190 and the output of the 200 will flow into the other output, an element having directionality such as an isolator is mounted on each output. By doing so, the inflow to each other's output may be suppressed.

(Fourth embodiment)
Next, a fourth embodiment of the envelope tracking power supply according to the present invention will be described with reference to FIG. FIG. 8 is a block diagram showing a configuration example of the envelope tracking power supply 214 in the fourth embodiment of the present invention.
In FIG. 8, the envelope tracking power supply 214 compares the input terminal 100, the output terminal 109, the synthesis amplifier 110, the switches 140 and 141, the phase / amplitude adjustment unit 128, and the input signal 101 with a preset threshold value. A threshold value comparison unit 142, control signals 144 and 145 for controlling the switches 140 and 141, and a voltage source 170, respectively.

  A signal line from the input terminal 100 is connected to an input of the switch 140. One output of the switch 140 is connected to the input of the synthesis amplifier 110. The circuits in the synthesis amplifier 110 are connected in the same manner as in the embodiment of FIG. The output of the synthesis amplifier 110 is connected to one input of the switch 141. The other output of the switch 140 is connected to the input of the phase / amplitude adjustment unit 128. The output of the phase / amplitude adjustment unit 128 is connected to the input of the voltage source 170. The output of the voltage source 170 is connected to the other input of the switch 141. The output of the switch 141 is connected to the output terminal 109. One output of the threshold comparison unit 142 is connected to the control input of the switch 140, and the other output of the threshold comparison unit 142 is connected to the control input of the switch 141. The input of the threshold comparison unit 142 is connected to the baseband unit 801 or the input terminal 100.

  In the present embodiment, the voltage source 170 is configured as shown in FIGS. 11 and 12, and can output a plurality of discrete fixed voltages or analog voltages. Further, as a control input signal to the threshold comparison unit 142, a control signal from the baseband unit 801 may be used, or the analog signal 101 may be used.

The operation will be described below using the block diagram of FIG. 8, the input signal waveform of FIG. 9, and the flowchart of FIG. FIG. 9 is a signal waveform for explaining the operation of the threshold comparison unit shown in FIG. FIG. 10 is a flowchart for explaining the operation of the threshold comparison unit shown in FIG.
In this example, two fixed voltages are set as the voltage source 170. In FIG. 10, when the operation of the threshold comparison unit 142 is started, the threshold comparison unit 142 determines whether there is an input signal 101 to the input terminal 100 in FIG. 8 (step S010). Exit. If there is the input signal 101, the threshold comparison unit 142 acquires the level of the input signal 101 (step S011). Next, the threshold value comparison unit 142 compares the input signal 101 with the threshold value 1 (step S012). When the input signal 101 is less than or equal to the threshold value 1 (N in step S012), the switch 140 connects the input terminal 100 and the input of the synthesis amplifier 110, and the switch 141 connects the output of the synthesis amplifier 110 and the output terminal 109 ( Step S019). Thereafter, the threshold comparison unit 142 waits for the next input signal (step 010). When the input signal 101 is larger than the threshold value 1 (Y in step S012), the switch 140 connects the input terminal 100 and the input of the phase / amplitude adjustment unit 128, and the switch 141 connects the output of the voltage source 170 and the output terminal 109. Connect (step S013). Next, the input signal 101 is compared with the threshold value 2 (step S014). When the input signal 101 is larger than the threshold 2 (Y in step S014), the voltage 2 of the voltage source 170 is output as the output signal 107 (step S015), and the threshold comparison unit 142 waits for the next input signal (step S010). ). In step S014, when the input signal 101 is equal to or less than the threshold 2 (N in step S014), the voltage 1 of the voltage source 170 is output as the output signal 107 (step S016), and the process returns to step 010.

  In the processing example of the above flowchart, two fixed voltages (voltage 1 and voltage 2) are used as the voltage source 170. However, one fixed voltage (FIG. 9C) or three or more fixed voltages are used. Even when a voltage is used, those skilled in the art can appropriately change the processing flow. When a plurality of fixed voltages are used, a voltage obtained by converting an analog signal into a discrete signal may be output by operating at a higher speed than the input signal 101 (FIG. 9D). A corrected analog output may be output by using an error amplifier for the converted discrete signal (FIG. 9 (e)).

An example of the circuit configuration for obtaining the voltage source 170 of FIG. 8 and the output shown in FIGS. 9D and 9E is shown in FIGS. FIG. 11 is a circuit for realizing the output waveform of FIG. 11, the voltage source 170 includes a fixed voltage source 701, a plurality of DCDC converters 702, 703, and 704 that step up and down from the output voltage of the fixed voltage source 701 and convert them to a constant voltage, and DCDC converters 702, 703, and 704. Switches 705, 706, 707, and 708 that switch the output and output the signal 107, and a switch controller 709 that determines which switch to switch are provided. The above determination may be performed by the baseband unit 801, and the determination result may be input to the switch controller 709 as the control signal 710 to configure the control circuit of FIG. 11 or the input 710 to the switch controller 709 may be configured. Is an analog input signal 101, it may be configured as a judgment / control circuit by a simple logic and a comparator. In addition, the system should be designed in consideration of delay and the like so that the output of the voltage source 170 is output at an appropriate timing.
FIG. 12 is a circuit for realizing the output waveform of FIG. In FIG. 12, the voltage source 170 further includes an analog correction circuit (error amplifier) 711.
In the above, the voltage 1 is set to the same value as or larger than the threshold value 2, and the voltage 2 is set to the maximum output voltage. The threshold 1 and the threshold 2 are parameters determined by the voltage distribution of the input signal 101 and the efficiency and distortion of the synthesis amplifier 110 and the voltage source 170.

  In summary, in the present embodiment, in the case of an input signal having a threshold value of 1 or less, a signal that follows the envelope is output from the synthesis amplifier 110, and in the case of an input signal that is greater than the threshold value 1, it is discrete from the voltage source 170. Outputs a voltage that is loosely followed by a value or analog. Alternatively, the voltage source 170 may be set so as to follow with high accuracy. The degree of analog output tracking of the output voltage from the voltage source 170 is determined in consideration of circuit scale, power consumption, efficiency, distortion, and the like. When the output voltage 107 from the voltage source 170 is output as a discrete value, the minimum voltage (eg, voltage 1) among a plurality of discrete values (eg, voltage 1 and voltage 2) exceeding the input signal 103 is used. 1) is output. As a result, among the plurality of discrete value voltages that can be output, the minimum voltage that amplifies the signal without distortion is output, so that high efficiency can be obtained in input signal amplification.

An ET (Envelope Tracking) power amplifier to which the configuration of the present embodiment is preferably applied will be described with reference to FIG. The envelope tracking power supply 615 in FIG. 14 is replaced with the envelope tracking power supply 214 in FIG. 8, so that the Class-BD synthesis amplifier 110 is used as the envelope for a small amplitude (low voltage) input signal. The followed output voltage 605 is applied as a power supply voltage (drain voltage or the like) of the main amplifier 613. By limiting the input signal to a small amplitude (low voltage), the envelope tracking power supply 214 exhibits high efficiency, and also when amplified by the main amplifier 613, the back-off with respect to the input signal is small, so the entire ET power amplifier High efficiency is achieved (follow-up mode).
On the other hand, for an input signal having a large amplitude (high voltage), the output from the envelope tracking power supply 214 becomes a fixed voltage set by the voltage source 170 and performs normal linear amplification (hereinafter referred to as a linear mode). . If the settable fixed voltage value is large, the backoff amount becomes small with respect to the input signal, and the efficiency of the envelope tracking power supply 214 is improved, but the circuit is complicated. Further, as shown in FIG. 6, since the ratio of the large amplitude signal is small, it is considered that the efficiency when operating in the linear mode is allowed even if it is somewhat low. The number of fixed voltages set by the voltage source 170 is determined in consideration of circuit scale, efficiency, distortion, and the like.
In addition, when a signal with a very low voltage near 0 V is input, the gain of the main amplifier 613 may be reduced, causing distortion. In this case, for an input signal in the vicinity of 0 V, for example, an input signal having a normalized voltage of 0 to 0.1, the envelope tracking power supply 214 is linearly operated, and the normalized voltage is 0.1 to 0.6. For example, the envelope tracking power supply 214 can be operated to follow the input signal, and the envelope tracking power supply 214 can be linearly operated for an input signal having a normalized voltage of 0.6 to 1. . A numerical example of the normalized voltage that separates linear operation and tracking operation is determined by device characteristics, input signal characteristics, and power amplifier specifications (such as distortion).

According to the present embodiment, although depending on the configuration of the voltage source 170, the envelope tracking power supply 214 with high efficiency is realized by a relatively simple circuit configuration.
Also in this embodiment, as in the embodiment of FIG. 5, an amplitude limiting limiter 169 may be used instead of the switch. That is, after branching the input signal 101, the limiter 169 may be used as the input of the synthesis amplifier 110, and the output of the synthesis amplifier 110 and the output of the voltage source 170 may be synthesized by a synthesizer.

(5th Example)
Next, a fifth embodiment of the envelope tracking power supply according to the present invention will be described with reference to FIG. FIG. 13 is a block diagram showing a configuration example of the envelope tracking power supply 215 in the fifth embodiment of the present invention. In FIG. 13, an envelope tracking power source 215 includes an input terminal 100, an output terminal 109, a synthesis amplifier 110, a synthesizer 194, phase / amplitude adjustment units 128 and 129, a low-pass filter 135, and a high-pass filter. 136 and a pulse generator 171.
A signal line from the input terminal 100 is connected to an input of the phase / amplitude adjustment unit 128. The output of the phase / amplitude adjustment unit 128 is connected to the input of the synthesis amplifier 110. The output of the synthesis amplifier 110 is connected to the input of the low-pass filter 135. A control signal 146 is connected to the input of the phase / amplitude adjustment unit 129. The control signal 146 is a signal generated based on the baseband unit 801 or the input signal 101. The output of the phase / amplitude adjustment unit 129 is connected to the input of the pulse generation unit 171. The output of the pulse generator 171 is connected to the input of the high pass filter 136. The output of the low pass filter 135 and the output of the high pass filter 136 are connected to the input of the synthesizer 194. The output of the synthesizer 194 is connected to the output terminal 109.

  In this embodiment, the input signal 101 is called a low-frequency filter (not shown) or a digital signal processing in the baseband unit 801 and is called a DC component and a low-frequency signal (low frequency compared to the envelope band). Signal processing is performed in the preceding stage of the input terminal 100 so that the meaning) is input. The pulse generator 171 is triggered by the control signal 146 at the timing when the high frequency signal is input, generates the pulse voltage 107, and adds it to the output signal 106 from the synthesis amplifier 110. At this time, if the pulse generator 171 can output a plurality of pulses having amplitudes and pulse widths, a control signal 146 that obtains an output having a desired amplitude and pulse width is sent to the pulse generator 171. Entered. Further, the pulse generator 171 can also be configured by a high-efficiency power amplifier such as class C or class E. In that case, the control signal 146 is an envelope signal in a high frequency band (meaning a high frequency side in the envelope signal), and the input of the control signal 146 is amplified by the pulse generator 171 and output. The pulse generator 171 is realized by a known general circuit.

In the above description, the input signal to the synthesis amplifier 110 is limited by the frequency, such as a DC component and a low-frequency signal, but may be limited by a DC component, a low-frequency signal, and a signal having a small amplitude. Alternatively, a low slew rate signal (a signal having a small dV / dt) may be used as an input signal to the synthesis amplifier 110. In that case, signals other than those are output by the pulse generator 171.
With regard to the synthesizer 194, in this embodiment as well, it can be directly connected as shown in FIG. 5 or a switch can be used as shown in FIG. 8, but it is preferably constituted by a transformer. The phase / amplitude adjustment units 128 and 129 not only adjust the amplitude and phase shift generated in the circuits and lines of the synthesis amplifier 110 and the pulse generation unit 171, but particularly when the synthesizer 194 includes a transformer, the transformer 194 The phase shift of 180 degrees accompanying the signal transmission from the primary side to the secondary side is adjusted. These phase / amplitude adjustment units 128 and 129 analyze the difference between the signal waveform such as the output signal 108 and the desired signal waveform, and adjust the phase and amplitude so that the desired waveform is obtained at the output terminal 109. It is also possible to do.

  In this embodiment, by limiting the input frequency to the synthesis amplifier 110, it is possible to avoid the problem that high-efficiency amplification cannot be performed in the high-frequency band, and the overall efficiency of the envelope tracking power supply 215 is also increased. In addition, the error amplifier 111 constituting the synthesis amplifier 110 is highly feasible because it has a specification that limits the input frequency in a predetermined band. In addition, since no switching element is used in the division of the input signal or the output synthesis, the synthesis amplifier 110 and the pulse generator 171 do not generate an operation discontinuity point due to the switching of the input signal and the output. Therefore, the operations of the synthesis amplifier 110 and the pulse generator 171 are stable, and the generation of distortion components is avoided. As in the first embodiment, the switching noise generated from the synthesis amplifier 110 can be suppressed by the low-pass filter 135 and a signal with small distortion can be output.

Although the power amplifier using this embodiment depends on the configuration of the pulse generator 171, the pulse generator 171 is a simple pulse generator 171 that does not faithfully reproduce an input waveform such as a simple rectangular wave. In some cases, distortion caused by the EER operation increases. Therefore, this configuration is preferably implemented for ET (Envelope Tracking). However, since the configuration, performance, EER, and ET application of the pulse generator 171 are intricately intertwined with circuit scale, efficiency, stability, distortion, input waveform, etc., they are optimally designed according to the overall target performance. Should.
Also in this embodiment, as in the fourth embodiment, the input signal can be limited not by frequency but by amplitude.

Based on the above description of the present specification, at least the following invention can be grasped. That is, the power supply circuit of the first invention is
A power supply circuit comprising a first voltage generator and a second voltage generator,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, the output of the inductor is connected to the other end of the sense resistor, and the error amplifier generates the same voltage at the output terminal of the error amplifier as the input signal to its input terminal, The current flows out from the output terminal or the current flows into the output terminal,
Generating an output voltage obtained by amplifying an input signal of a predetermined frequency or less in the first voltage generator and generating an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generator; or The first voltage generator generates an output voltage obtained by amplifying an input signal having a predetermined amplitude or less, and the second voltage generator generates an output voltage corresponding to an input signal having an amplitude larger than the predetermined amplitude.
The output from the first voltage generator and the output from the second voltage generator are combined.
By configuring the power supply circuit in this manner, it is possible to provide a power supply circuit having high-efficiency and wideband characteristics that can be applied to a wideband wireless system that enables high-speed transmission.

The power supply circuit of the second invention is the power supply circuit of the first invention, wherein the input signal to the first voltage generation unit and the second voltage generation unit is a filter, a switch, or a combination of both. It is limited by the thing.
When the power supply circuit is configured in this way, the input signals to the first voltage generation unit and the second voltage generation unit can be easily separated.

According to a third aspect of the present invention, there is provided the power supply circuit according to the first aspect, wherein the input signal input to the first voltage generation unit and the second voltage generation unit is discriminated by digital signal processing in advance. Features.
By configuring the power supply circuit in this manner, the circuit configuration of the power supply circuit can be simplified, and the input signals to the first voltage generation unit and the second voltage generation unit can be easily separated.

A power supply circuit according to a fourth invention is the power supply circuit according to any one of the first to third inventions, wherein the output from the first voltage generation unit and the output from the second voltage generation unit are a transformer, or It is synthesized by a filter, a switch, an isolator, or a combination thereof.
When the power supply circuit is configured in this way, a desired signal is transmitted to the output terminal 109 without the output signal from the first voltage generator and the output signal from the second voltage generator flowing into each other. Easy to do.

According to a fifth aspect of the present invention, there is provided the power supply circuit according to the second aspect, wherein the switch is controlled based on an input signal to the power supply circuit.
By configuring the power supply circuit in this way, it is possible to easily generate a timing for switching the switch.

A power supply circuit according to a sixth aspect of the present invention is the power supply circuit according to the first aspect, wherein the input signal transmission path or the output signal transmission path of the first voltage generator, or the input signal transmission path of the second voltage generator. Alternatively, at least one delay element or attenuator is provided at any position on the output signal transmission line.
By configuring the power supply circuit in this way, it is possible to easily adjust the delay amount and gain between the first voltage generation unit and the second voltage generation unit.

A power circuit according to a seventh aspect is the power circuit according to the sixth aspect, wherein the delay amount of the delay element and the attenuation amount of the attenuator are determined based on an input signal to the power circuit or an output signal from the power circuit. It is characterized by adjusting.
By configuring the power supply circuit in this way, the delay amount and gain between the first voltage generation unit and the second voltage generation unit can be easily adjusted according to the amplitude and frequency of the input signal.

The power supply circuit according to an eighth aspect of the present invention is the power supply circuit according to the first aspect, wherein the first voltage generator or the second voltage generator is based on an input signal to the power supply circuit or an output signal from the power supply circuit. The voltage applied to the constituent elements of the voltage generator is controlled.
When the power supply circuit is configured in this way, the voltage applied to the first voltage generation unit and the second voltage generation unit can be optimally controlled according to the amplitude and frequency of the input signal. Increases efficiency.

The power amplifier of the ninth invention is
A power amplifier comprising a main amplifier and a power supply circuit for supplying a power supply voltage to the main amplifier,
The power supply circuit is a power supply circuit that varies an output voltage based on an envelope of an input signal input to the power amplifier, and includes a first voltage generation unit and a second voltage generation unit. ,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, the output of the inductor is connected to the other end of the sense resistor, and the error amplifier generates the same voltage at the output terminal of the error amplifier as the input signal to its input terminal, The current flows out from the output terminal or the current flows into the output terminal,
The power supply circuit generates an output voltage obtained by amplifying an input signal having a frequency equal to or lower than a predetermined frequency in the first voltage generation unit, and outputs an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generation unit. Or an output voltage corresponding to an input signal having an amplitude larger than a predetermined amplitude in the second voltage generation unit, while generating an output voltage obtained by amplifying an input signal having a predetermined amplitude or less in the first voltage generation unit And a power supply circuit that synthesizes the output from the first voltage generator and the output from the second voltage generator.
By configuring the power amplifier in this way, it is possible to provide a power amplifier having high efficiency and wide band characteristics that can be applied to a wide band wireless system that enables high speed transmission.

A power amplifier according to a tenth invention is the power amplifier according to the ninth invention, wherein the second voltage generator includes a Doherty-type power amplifier, and the first voltage generator amplifies an input signal having a predetermined frequency or less. In the second voltage generation unit, the Doherty power amplifier amplifies an input signal having a frequency higher than a predetermined frequency.
When the power amplifier is configured in this way, the specification of the error amplifier can be relaxed from a high voltage and a wide band to a high voltage and a narrow band, and an input signal can be amplified while suppressing distortion. . Further, since the high-frequency signal is amplified with high efficiency by the Doherty type power amplifier, the power amplifier according to the tenth aspect of the invention can be amplified with high efficiency over all bands.

The power amplifier according to an eleventh aspect is the power amplifier according to the ninth aspect, wherein the second voltage generator includes a peak amplifier, and the first voltage generator amplifies an input signal having a predetermined amplitude or less, In the second voltage generator, a peak amplifier amplifies an input signal having an amplitude larger than a predetermined amplitude.
When the power amplifier is configured in this manner, the specification of the error amplifier can be relaxed and the efficiency of the power amplifier can be increased with a very simple configuration.

A power amplifier according to a twelfth aspect is the power amplifier according to the ninth aspect, wherein the second voltage generator includes an error amplifier to which an input signal to the second voltage generator is input, and the error amplifier. A sense resistor having one end connected to the output terminal of the output terminal, a sense circuit unit that generates a control signal based on a voltage generated between the sense resistors, and a switching operation based on the control signal from the sense circuit unit A switching amplifier unit that outputs current and an inductor that smoothes the output from the switching amplifier, and the output of the inductor is connected to the other end of the sense resistor, and the error amplifier has its input terminal In order to generate the same voltage as the input signal to the output terminal of the error amplifier, current flows out from the output terminal or current flows into the output terminal.
The first voltage generating unit amplifies an input signal having a frequency lower than a predetermined frequency, and the second voltage generating unit amplifies an input signal having a frequency higher than the predetermined frequency.
When the power amplifier is configured in this way, it is possible to relax the specifications of the error amplifier used in the first voltage generation unit and the second voltage generation unit, and it is possible to achieve high efficiency of the power amplifier.

A power amplifier according to a thirteenth aspect is the power amplifier according to the ninth aspect, wherein the second voltage generation unit includes a power source that outputs one or a plurality of fixed voltages, and the first voltage generation unit includes: Amplifying an input signal having a frequency lower than a predetermined frequency and generating a fixed voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generator, or having a frequency lower than a predetermined amplitude in the first voltage generator The input signal is amplified and the second voltage generator generates a fixed voltage corresponding to the input signal having an amplitude larger than a predetermined amplitude.
When the power amplifier is configured in this way, a highly efficient power amplifier is realized with a simple circuit configuration.

A power amplifier according to a fourteenth aspect is the power amplifier according to the thirteenth aspect, wherein the second voltage generator includes an error amplifier that compensates for a difference between the output voltage and a discrete fixed voltage, and includes a plurality of fixed voltages. In the case of outputting in (3), an analog voltage is output.
When the power amplifier is configured in this way, the back-off amount is small with respect to the input signal, and thus a highly efficient power amplifier is realized.

A power amplifier according to a fifteenth aspect is the power amplifier according to the ninth aspect, wherein the second voltage generator includes a pulse generator, and the first voltage generator amplifies an input signal having a predetermined frequency or less. In addition, the second voltage generator generates a pulse corresponding to an input signal having a frequency higher than a predetermined frequency by the pulse generator, or amplifies an input signal having a predetermined amplitude or less by the first voltage generator. At the same time, the second voltage generator generates a pulse corresponding to an input signal having an amplitude larger than a predetermined amplitude by the pulse generator.
When the power amplifier is configured in this way, a highly efficient power amplifier is realized with an easy circuit configuration.

The radio base station of the sixteenth invention is
A radio base station including an analog unit that performs transmission / reception signal amplification processing and frequency conversion processing, and a baseband unit that performs modulation / demodulation processing of the transmission / reception signal and control of the analog unit,
The analog unit includes a power amplifier that performs amplification processing of a transmission signal,
The power amplifier includes a main amplifier and a power supply circuit that supplies a power supply voltage to the main amplifier.
The power supply circuit includes a first voltage generation unit and a second voltage generation unit,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
The power supply circuit generates an output voltage obtained by amplifying an input signal having a frequency equal to or lower than a predetermined frequency in the first voltage generation unit, and outputs an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generation unit. Or an output voltage corresponding to an input signal having an amplitude larger than a predetermined amplitude in the second voltage generation unit, while generating an output voltage obtained by amplifying an input signal having a predetermined amplitude or less in the first voltage generation unit And the output from the first voltage generator and the output from the second voltage generator are combined.
By configuring the radio base station in this way, it is possible to provide a radio base station having high efficiency and wide band characteristics that can be applied to a wide band radio system that enables high-speed transmission.

A radio base station according to a seventeenth aspect is the power supply circuit of the radio base station according to the sixteenth aspect, wherein the switch is controlled based on an input signal to the power supply circuit or a control signal from the baseband unit. It is characterized by that.
When the radio base station is configured in this way, the timing for switching the switch can be easily generated.

A radio base station according to an eighteenth aspect of the invention is the power supply circuit of the radio base station of the sixteenth aspect of the invention, based on an input signal to the power supply circuit or a control signal from the baseband unit, The attenuation amount of the attenuator is adjusted.
When the radio base station is configured in this way, the delay amount and gain between the first voltage generation unit and the second voltage generation unit can be easily adjusted according to the amplitude and frequency of the input signal. .

A radio base station according to a nineteenth aspect is the power supply circuit of the radio base station according to the sixteenth aspect, wherein the first voltage generation is based on an input signal to the power supply circuit or a control signal from the baseband unit. Or a voltage applied to the second voltage generator is controlled.
When the radio base station is configured in this way, it is possible to optimally control the applied voltage to the constituent elements of the first voltage generation unit and the second voltage generation unit according to the amplitude and frequency of the input signal. This improves the efficiency of the power supply circuit.

  DESCRIPTION OF SYMBOLS 100 ... Input terminal, 101 ... Input signal, 106 ... Output signal from synthetic | combination amplifier 110, 107 ... Output signal from Doherty-type power amplifier 120, 108 ... Output signal, 109 ... Output terminal, 110 ... Synthetic amplifier, 111, 111A , 111B ... error amplifier, 112, 112A, 112B ... sense resistor, 113, 113A, 113B ... sense circuit section, 114, 114A, 114B ... switching amplifier, 115, 115A, 115B ... inductor, 120 ... Doherty type power amplifier, DESCRIPTION OF SYMBOLS 121 ... Distributor, 122 ... Synthesizer, 123 ... Carrier amplifier, 124 ... Peak amplifier, 125, 126 ... 90 degree phase shifter, 128, 129 ... Phase / amplitude adjustment part, 131, 133, 135 ... Low pass filter 132, 134, 136... High pass filter, 140, DESCRIPTION OF SYMBOLS 41 ... Switch, 142 ... Threshold comparison part, 144, 145, 146 ... Control signal, 150 ... Class C amplifier, 161, 162 ... Isolator, 163, 167 ... Peak signal, 169 ... Limiter, 170 ... Voltage source, 171 ... Pulse Generating unit, 180 ... Penetration prevention logic unit, 181 ... High Side MOS, 182 ... Low Side MOS, 190 ... Synthetic amplifier, 191 ... Distributor, 192,194 ... Synthesizer, 200 ... Synthetic amplifier, 211-215 ... Envelope Tracking power supply, 500... Voltage gain frequency characteristic of the synthesis amplifier 110, 501 to 503... Voltage gain frequency dependency of the Doherty amplifier 120, 504 to 506. ... Input signal, 602,603 ... Phase signal, 604,605 ... (Envelope) signal, 606 ... RF signal, 611 ... limiter, 612 ... delay unit, 613 ... main amplifier (saturation amplifier), 614 ... amplitude detector, 615 ... envelope tracking power supply, 617 ... power load impedance, 801 ... Baseband part, 802 ... Network interface part, 803 ... Processor, 804 ... Memory, 805,806 ... Signal processing part, 810,811 ... Analog part, 820 ... RF part, 825 ... Control signal, 830 ... Front end part, 831: Power amplifier, 832: Low noise amplifier, 833: Transmission / reception selector switch, 841, 842: Antenna.

Claims (19)

A power supply circuit comprising a first voltage generator and a second voltage generator,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
Generating an output voltage obtained by amplifying an input signal of a predetermined frequency or less in the first voltage generator and generating an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generator; or The first voltage generator generates an output voltage obtained by amplifying an input signal having a predetermined amplitude or less, and the second voltage generator generates an output voltage corresponding to an input signal having an amplitude larger than the predetermined amplitude.
A power supply circuit that combines the output from the first voltage generator and the output from the second voltage generator. The power supply circuit according to claim 1,
A power supply circuit, wherein an input signal to the first voltage generation unit and the second voltage generation unit is limited by a filter, a switch, or a combination of both. The power supply circuit according to claim 1,
A power supply circuit characterized in that an input signal input to the first voltage generator and the second voltage generator is discriminated in advance by digital signal processing. The power supply circuit according to claim 1,
A power supply characterized in that the output from the first voltage generator and the output from the second voltage generator are synthesized by a transformer, a filter, a switch, an isolator, or a combination thereof. circuit. The power supply circuit according to claim 2,
The power supply circuit, wherein the switch is controlled based on an input signal to the power supply circuit. The power supply circuit according to claim 1,
At least one delay element or attenuator at any position of the input signal transmission path or output signal transmission path of the first voltage generator or the input signal transmission path or output signal transmission path of the second voltage generator A power supply circuit comprising: The power supply circuit according to claim 6,
A power supply circuit, wherein a delay amount of a delay element and an attenuation amount of an attenuator are adjusted based on an input signal to the power supply circuit or an output signal from the power supply circuit. The power supply circuit according to claim 1,
A voltage applied to a component of the first voltage generation unit or the second voltage generation unit is controlled based on an input signal to the power supply circuit or an output signal from the power supply circuit. Power supply circuit. A power amplifier comprising a main amplifier and a power supply circuit for supplying a power supply voltage to the main amplifier,
The power supply circuit is a power supply circuit that varies an output voltage based on an envelope of an input signal input to the power amplifier, and includes a first voltage generation unit and a second voltage generation unit. ,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
The power supply circuit generates an output voltage obtained by amplifying an input signal having a frequency equal to or lower than a predetermined frequency in the first voltage generation unit, and outputs an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generation unit. Or an output voltage corresponding to an input signal having an amplitude larger than a predetermined amplitude in the second voltage generation unit, while generating an output voltage obtained by amplifying an input signal having a predetermined amplitude or less in the first voltage generation unit And a power circuit that synthesizes the output from the first voltage generator and the output from the second voltage generator. The power amplifier according to claim 9, wherein
The second voltage generator includes a Doherty power amplifier, the first voltage generator amplifies an input signal having a predetermined frequency or less, and the Doherty power amplifier is higher than a predetermined frequency in the second voltage generator. A power amplifier that amplifies a frequency input signal. The power amplifier according to claim 9, wherein
The second voltage generation unit includes a peak amplifier, and the first voltage generation unit amplifies an input signal having a predetermined amplitude or less, and the second voltage generation unit has an input signal having an amplitude larger than a predetermined amplitude. A power amplifier. The power amplifier according to claim 9, wherein
The second voltage generator includes an error amplifier to which an input signal to the second voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
A power amplifier, wherein the first voltage generator amplifies an input signal having a frequency lower than a predetermined frequency, and the second voltage generator amplifies an input signal having a frequency higher than a predetermined frequency. The power amplifier according to claim 9, wherein
The second voltage generation unit includes a power source that outputs one or a plurality of fixed voltages, the first voltage generation unit amplifies an input signal having a predetermined frequency or less, and the second voltage generation unit A fixed voltage corresponding to an input signal having a frequency higher than the frequency is generated, or an input signal having a predetermined amplitude or less is amplified by the first voltage generation unit, and an amplitude larger than a predetermined amplitude by the second voltage generation unit A power amplifier that generates a fixed voltage corresponding to the input signal. The power amplifier according to claim 13.
The second voltage generator includes an error amplifier that compensates for a difference between an output voltage and a discrete fixed voltage, and outputs an analog voltage when outputting with a plurality of fixed voltages. amplifier. The power amplifier according to claim 9, wherein
The second voltage generator includes a pulse generator, and the first voltage generator amplifies an input signal having a predetermined frequency or less and a frequency higher than the predetermined frequency by the pulse generator in the second voltage generator. Or a signal having an amplitude larger than a predetermined amplitude by the pulse generator in the second voltage generator and amplifying an input signal having a predetermined amplitude or less by the first voltage generator. A power amplifier that generates a pulse corresponding to an input signal. A radio base station including an analog unit that performs transmission / reception signal amplification processing and frequency conversion processing, and a baseband unit that performs modulation / demodulation processing of the transmission / reception signal and control of the analog unit,
The analog unit includes a power amplifier that performs amplification processing of a transmission signal,
The power amplifier includes a main amplifier and a power supply circuit that supplies a power supply voltage to the main amplifier.
The power supply circuit includes a first voltage generation unit and a second voltage generation unit,
The first voltage generator includes an error amplifier to which an input signal to the first voltage generator is input, a sense resistor having one end connected to the output terminal of the error amplifier, and the sense resistor A sense circuit unit that generates a control signal based on the generated voltage, a switching amplifier unit that performs a switching operation based on the control signal from the sense circuit unit and outputs a current, and an output from the switching amplifier A smoothing inductor, and the output of the inductor is connected to the other end of the sense resistor,
The power supply circuit generates an output voltage obtained by amplifying an input signal having a frequency equal to or lower than a predetermined frequency in the first voltage generation unit, and outputs an output voltage corresponding to an input signal having a frequency higher than the predetermined frequency in the second voltage generation unit. Or an output voltage corresponding to an input signal having an amplitude larger than a predetermined amplitude in the second voltage generation unit, while generating an output voltage obtained by amplifying an input signal having a predetermined amplitude or less in the first voltage generation unit And the output from the first voltage generator and the output from the second voltage generator are combined. The radio base station according to claim 16,
The switch is controlled based on an input signal to the power supply circuit or a control signal from the baseband unit. The radio base station according to claim 16,
A radio base station that adjusts a delay amount of a delay element and an attenuation amount of an attenuator based on an input signal to the power supply circuit or a control signal from the baseband unit. The radio base station according to claim 16,
A radio base station that controls an applied voltage of the first voltage generation unit or the second voltage generation unit based on an input signal to the power supply circuit or a control signal from the baseband unit .

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