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High-fidelity D type voice frequency amplifier

A technology for audio amplifiers and power amplifiers, applied to amplifiers, improved amplifiers to reduce nonlinear distortion, amplifiers with semiconductor devices/discharge tubes, etc., can solve problems such as index deterioration, achieve high PSRR, ensure stability, and suppress Effect of PWM Signal Phase and Duty Cycle Errors

Inactive Publication Date: 2012-12-19
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the feedback network of this type of amplifier cannot effectively suppress the phase and duty cycle errors of the PWM signal generated by the nonlinear modulation mode, the resulting distortion has become very obvious. The main manifestations are IMD (Intermodulation Distortion) and PSRR (Power Supply Rejection Ratio) ) indicators of deterioration

Method used

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  • High-fidelity D type voice frequency amplifier
  • High-fidelity D type voice frequency amplifier
  • High-fidelity D type voice frequency amplifier

Examples

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Embodiment

[0037] The high-fidelity class-D audio amplifier of the present invention belongs to PWM-type class-D amplifier and includes a preamplifier, a secondary amplifier, a PWM modulation circuit, a drive circuit (including driver 1 and driver 2), a power amplifier and a feedback network G. Such as image 3shown. In this example, the feedback network G adopts an active RC filter network, which is connected between the output terminal of the power amplifier and the input terminal of the secondary amplifier. In the figure, the secondary amplifier is composed of a fully differential operational amplifier OP2, and the preamplifier is composed of a fully differential operational amplifier OP1. The input terminals of the fully differential operational amplifier OP1 are respectively connected to the first input signal V IN1 and the second input signal V IN2 , whose output is connected to the fully differential operational amplifier OP2. The two signals V output by the fully differential...

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Abstract

The invention relates to a voice frequency power amplifier, and discloses a high-fidelity D type voice frequency amplifier aiming at the shortcoming of a filter-free D type voice frequency amplifier in the prior art, which improves the performance index of the filter-free D type voice frequency amplifier by improvement of a feedback network and optimum design of a circuit. The high-fidelity D type voice frequency amplifier comprises a preamplifier, a two-stage amplifier, a PWM (pulse width modulation) circuit, a driving circuit, a power amplifier and a feedback network, wherein the feedback network adopts an active RC (resistance-capacitance) filter network, effectively inhibits the errors of PWM signal phase and duty ratio in the modulation process, realizes superior total harmonic distortion (THD) and noise performance index and has lower intermodulation distortion (IMD) as compared with the traditional resistance feedback network. The voice frequency power amplifier has the characteristics of high efficiency, low power consumption and high PSRR (power supply rejection ratio), guarantees the stability of the whole amplifier and is very suitable for the requirements of mobile communication equipment and other portable type systems.

Description

technical field [0001] The present invention relates to an audio frequency power amplifier, in particular to a pulse width modulation (PWM) class D audio amplifier circuit and a monolithic integrated circuit formed therefrom. Background technique [0002] Class D amplifiers are also called digital amplifiers, and the main difference from analog amplifiers is the working state of the power amplifier tube. Traditional analog amplifiers include Class A, Class B, Class A and B, and Class C. The general small-signal amplification is a Class A power amplifier, that is, Class A. The amplifying device needs to be biased, and the amplitude of the amplified output cannot exceed the bias range. Therefore, the energy conversion efficiency is very low, and the theoretical efficiency is only 25%. Class B amplifiers, also known as Class B amplifiers, do not require bias, and rely on the signal itself to turn on the amplifier tube, and the ideal efficiency is as high as 78.5%. But because...

Claims

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Application Information

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IPC IPC(8): H03F1/32H03F3/217
CPCY02B60/50
Inventor 明鑫张晓敏段茂平谢海武王卓周泽坤张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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