Digital Filter Design of A High Resolution Audio Sigma-delta ADC

The digital filter design of a high resolution audio sigma-delta ADC is proposed in this paper. The digital system is composed of cascaded integrator comb(CIC) filter, compensation filter and halfband filter. The design of digital decimation filter bandwidth is 24KHz, the input sampling frequency is 12.3MHz, the pass band ripple coefficient is ±0.01dB, and the stopband gain decays 120dB. By optimizing the structure, coefficients and order of the digital filter, the power consumption and the area of the system are reduced effectively. The behavial simulation shows the signal to noise ratio of the digital filter SNR is 100.6dB, and the accuracy is 16bit. The Sigma-delta ADC is implemented in TSMC 0.35μm CMOS process. The post simulation shows the overall dynamic range of the sigma-delta ADC is 97.4dB.