A multistage interpolation design of an audio DAC
Qin Kun, Tiejun Lu, Xiao Du, Wang Zongmin, Luo Binming · 2008
The concepts of digital signal processing are playing an increasingly important role in the area of multirate signal processing. The multistage interpolator main building blocks are a Cascaded Integrator-Comb (CIC) filter and the respective compensation filter and halfband filters. Their coefficients were attained from the MATLAB simulation. The CIC was designed to have 4 stages, a differential delay of 1 and a variable rate change factor of 16. A novel method based on CSD coding is proposed to realize a polyphase multiplier-free halfband subfilter with a high resolution. This approach reduces the complexity of the control system and saves chip area dramatically. The final designed interpolation filter's passband is in the region from -0.01dB to 0.01dB and the stop attenuation is 85dB.