由于中秋节假期,帖子审批以及工程师回复将会有所延迟,敬请谅解。

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TLV320AIC3254输入较大信号时AD转换结果异常

原理图如下图1所示,设置MIC共模电压0.9V,CODEC连接到DSP的MCASP接口,在MIC_IN处输入130mVp-p的正弦信号,频率1kHz,CODEC内部增益设置为20dB,理论上进入ADC的信号幅度为1.3V,未超出AD的量程(0.5Vrms),采集到的结果如下图2所示(纵轴是ADC数值),正半周的信号正常,负半周的信号出现了严重的畸变,请问是什么原因?

图1:

图2