Closed-loop feedback amplification circuit based on waveform predistortion and working method thereof

Abstract

The invention discloses a closed-loop feedback amplification circuit based on waveform predistortion, and the circuit comprises a predistortion waveform fitting device which is connected with a signal input port and an output sampling circuit; the digital-to-analog converter is used for receiving the fitting digital waveform signal of the pre-distortion waveform fitting device; the D-type power amplifier is used for respectively receiving an analog signal of the digital-analog converter and a closed-loop feedback signal of the closed-loop feedback circuit; and the adaptive filter is used for receiving the amplified signal of the D-type power amplifier. The D-type power amplification circuit based on hardware closed-loop feedback of the waveform pre-distortion technology has the advantages of being high in output stability, small in distortion degree, high in output efficiency, high in output bandwidth, small in phase delay, small in size, light in weight, high in reliability and the like; appropriate filters are selected according to different output parameters, the output efficiency of the power amplifier is improved, and the method can be used for standard power sources in the field of electric power measurement.

Description

technical field [0001] The invention relates to the technical field of power amplifiers, in particular to a closed-loop feedback amplifier circuit based on waveform predistortion and its working method. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] At present, the current power amplifier solutions in the field of electric power measurement are mainly divided into two categories. One is the linear power amplifier solution using ready-made integrated power amplifiers and discrete components, and the other is the SPWM switching power amplifier solution using Mos tubes for switching chopping. Linear integration The power amplifier solution generally adopts the existing integrated power amplifier of ADI or TI, which is commonly used as a high-power audio power amplifier. The problem with the direct audio power amplifier is that the bandwidth ...

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Problems solved by technology

[0003] At present, the current power amplifier solutions in the field of electric power measurement are mainly divided into two categories. One is the linear power amplifier solution using ready-made integrated power amplifiers and discrete components, and the other is the SPWM switching power amplifier solution using Mos tubes for switching chopping. Linear integration The power amplifier solution generally adopts the existing integrated power amplifier of ADI or TI, which is commonly used as a high-power audio power amplifier. The problem with the direct audio power amplifier is that the bandwidth is large enough, but there will be a few percent when the frequency is high Attenuation does not affect the audio power amplifier, but for the standard source power amplifier for power measurement, the accuracy is generally required to be within 0.1%, so it is difficult to meet the requirements, and its phase delay is relatively large. It is difficult to control the phase accuracy when the standard source power amplifier is used. At the same time, the efficiency is low, generally about 25%, and it is lower when the light load is output; the second is to use the SPWM switching power amplifier, the efficiency is high, generally can reach about 70%, there are problems Yes, the output frequency is limited by the SPWM carrier frequency. At present, the frequency of the general carrier is tens of KHz. In order to ensure the distortion of the output signal after filtering, the frequency of the signal in the general carrier needs to be lower than the carrier frequency by more than an order of magnitude, and the bandwidth is limited. The carrier is affected by the switching rate, the post-stage LC filter circuit and the stability of the loop. At present, the general signal output is pure 50Hz sine, or the superimposed harmonic of the power frequency. The harmonic frequency is generally less than 22 times, and the content rate is less than 20%. It is difficult to output wide-range, high-order, high-content harmonics, and the switching power amplifier cannot completely filter out the carrier, so the distortion is poor and the output stability is also poor. There is also an effect on the output

[0004] Therefore, in the field of power measurement, there are problems with current power amplifiers for standard power sources. Linear power amplifiers have high output stability and low distortion, but low efficiency. Switching power amplifiers have high output efficiency, but low output stability and large distortion. , so it is urgent to find a power amplifier device and its method that can take into account the advantages of linear power amplifiers and switching power amplifiers

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