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提出了一种双环反馈拓扑结构的D类音频功放。通过对基于脉冲宽度调制的D类功放反馈系统的分析,指出环路参数对总谐波失真THD和电源抑制比PSRR等性能有着重要的影响,讨论了如何通过参数优化来改善一阶单环反馈D类功放的THD指标。在此基础上提出了一种双环反馈拓扑结构,通过数学分析显示该二阶闭环系统的THD指标能得到更进一步地改善。测试结果显示,双环结构D类功放的THD较单环得到了7倍的改善。
A class D audio power amplifier with double loop feedback topology is proposed. By analyzing the feedback system of class D amplifier based on pulse width modulation (PWM), it is pointed out that the loop parameters have an important influence on THD and PSRR, and how to improve the performance of first-order single-loop feedback Class D amplifier THD indicators. Based on this, a double-loop feedback topology is proposed. The mathematical analysis shows that the THD index of the second-order closed-loop system can be further improved. The test results show that the THD of the double-loop structure class D amplifier is 7 times better than that of the single loop.