数字音频D类功放电源误差校正方法研究

为了实时校正供电电源噪声引起的数字音频D类功放输出误差,提出一种基于FPGA的电源误差校正方法。使用高精度ADC芯片将电源纹波信号转化为数字量后送入FPGA,校正模块根据电源纹波的大小对数字音频D类功放Sigma-Delta调制器输入值进行预校正处理,从而实现在功放输出端有效的抑制电源噪声。经过实际电路测试,该方法可以有效的抑制电源噪声对数字音频D类功放的影响,电源抑制比达到36.78 dB。

Power supply correction of digital audio class-D amplifier

In order to correct the error cased by the power supply noise of Digital audio class-D amplifier in real-time,a FPGA-based method is proposed in this paper.The power supply noise is transferred by a high solution ADC chip into digital signal, which is send to the FPGA,then the correction module pre-correct the input of Sigma-Delta modulator according to the power supply noise digital signal,make the power supply noise on the output of amplifier suppression effective.Circuit tesets proved that this method can effectively suppress the effect of power supply noise in digital audio class-D amplifier system and Power Supply Rejection Ratio（PSRR） of the system reached 36.78 dB.