1, the delta-sigma DPWM you mentioned should be the technology applied to DAC, ADC and Class D power amplifier, right? Δ-∑ DPWM is generally a low-precision code stream output by a Δ-∑ modulator, and then input to a bilateral PWM modulator to output a DPWM signal. Generally speaking, the oversampling module, namely the interpolation filter, needs to be added before the delta-sigma modulator. The delta-sigma modulator itself needs to input a high sampling rate signal to have the significance of noise shaping, that is, to push the quantization noise to a high frequency, thus reducing the quantization noise within the bandwidth.

2. Generally speaking, the delta-sigma modulator is better understood from the frequency domain, that is, the input signal is unchanged, and the quantization noise passes through the high-pass filter, thus reducing the signal accuracy and keeping the signal containing information. As for the back-end DPWM, assuming that the quantizer of the delta-sigma modulator connected to it is 4 bits and the sampling frequency is fs, the clock frequency of DPWM should reach FS * 2 4.

3.delta-sigma modulation signals are usually filtered by analog low-pass filters to remove high-frequency noise.