A comparison of efficient first stage decimation filters for continuous time delta sigma modulators

Low power, high signal to noise ratio, analog-to-digital converters are frequently required for biomedical applications. In addition, many such biomedical applications require high decimation rate digital filters; however, these digital filters demand significant power and circuit resources. Traditional multiplier-less cascaded integrated-comb (CIC) filter structure may be used but require large word lengths for high decimation rates. Alternatively, a cascaded minimum polyphase (CMP) structure provides a non-recursive multiplier-less decimation filter at reduced word lengths but additional filter sections. This work compares the circuit resource utilization and power consumption of the recursive and non-recursive structures. Considering small input word widths, single synchronous clock design, and hardware description synthesis, the CIC structure is more efficient than the CMP in the configurations tested.