Digital Filters for High Performance Audio Delta-sigma Analog-to-digital and Digital-to-analog Conversions

摘要

A multi-stage decimation filter is described which consists of comb filters and a single-stage finite impulse response (FIR) filter. A multi-rate comb filter structure is used to reduce the data path width. A multi-stage interpolation filter consists of a half-band filter and a short FIR filter. The short FIR filter is designed with a nonlinear phase to realize an overall constant group delay signal path. The coefficients of the FIR filters are optimally quantized to canonical-signed-digit form to realize multiplier-free (shift-and-add) filter implementations.