Feedback shift (FBS) type compensating network and application in audio power amplifier thereof

Abstract

The invention provides a feedback shift (FBS) type compensating network which can be used in the audio power amplifier and any negative feedback amplifying circuit with emitter or source follower output stage and can replace the traditional miller capacitance to provide phase-lag compensation. As the feedback network forms a local negative feedback with current-voltage amplifying stage and output stage in the frequency range above dominant pole, the degradation of circuit performance in the middle and high frequency range generally caused by the decrease of big ring negative feedback is made up to a certain extent so that the breakthrough increase of the indexes related to the output stage such as crossover distortion in middle and high frequency range is realized, the dependency of the circuit on the bias current of the power tube is greatly reduced, and a class AB amplifier which only uses tens of milliamps bias current can realize the crossover distortion level of the class A power amplifier or even less. The invention is a structural improvement for the traditional negative feedback amplifying circuit, the method is easy and the compensating network can be used in most of power amplifiers and other negative feedback amplifying circuits.

Description

technical field [0001] The invention relates to a feedback shift type (FBS) compensation network, which is suitable for a negative feedback amplifier using an emitter or a source follower in the final stage of an audio power amplifier, and belongs to the technical field of electronic circuits and audio. Background technique [0002] Traditional audio power amplifiers and integrated operational amplifiers using large-loop negative feedback linear amplifiers all adopt a classic three-stage circuit structure, such as figure 1 shown. The circuit consists of the first stage of amplification, which is the voltage-current input stage, the second stage of amplification, namely the current-voltage amplification stage, the third stage of amplification, namely the emitter stage or source follower output stage, a large-loop negative feedback network and for The hysteresis compensation capacitor (generally called Miller compensation capacitor or Miller capacitor) used to make the circui...

AI Technical Summary

Problems solved by technology

This Feedback Shift (FBS) compensation technology includes the final power transistor in a local negative feedback loop that is usually formed by a Miller capacitor in the mid-high frequency band of the audio, so that the Various performance indicators including crossover distortion have been greatly improved, thus fundamentally solving the problem of sound quality deterioration in the middle and high frequency bands of Class A and B transistor amplifiers

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