Dynamic range improvement in 2 nd -order low-pass multibit ΣΔ modulators

A circuit improving medium and low signal level SINAD in low-pass 2 nd -order double-sampled ΣΔ modulators is presented. It uses negligible silicon area without any power consumption. Basic understanding and detailed formulae have been confirmed by simulations and experimental results on a WCDMA baseband ADC fabricated in a 65nm CMOS process.