A Comparative Study and Design of Decimation Filter for High-Precision Audio Data Converters

This paper begins with comparing different high-level low-power design techniques for audio decimation filters. It then goes forward by presenting a multiplierless, low-power multi-stage digital filter for decimation in digital audio applications. A four-stage decimation filter with down-sampling factor of 128 is developed. A multi-stage CIC filter which reduces the sampling rate by 16 is used for the first stage. Two halfband filters and a FIR droop correction filter follow the CIC filter each reducing the sampling rate by two. Techniques to simultaneously achieve high performance and low power consumption are discussed in detail. The minimum stopband attenuation of the decimator is more than 120 dB and the passband ripple is less than 0.001 dB. The worst-case power and active area of the decimation filter are estimated using library of standard cells of 0.18μm CMOS process. Results of Matlab and Simulink simulations conclude this work.