A Beyond-the-rail Audio CTΔΣM with a Passive Input Stage and 99.2dB SNDR
Shuo Li, Sundeep Javvaji, V. Pecanins-Martinez, Eren Aydın, Robert van Veldhoven, K.A.A. Makinwa · 2024
This paper presents a 3rdorder continuous-time delta-sigma modulator (CT Δ ΣM) for audio applications. Its loop filter efficiently realizes complex conjugate NTF zeros by combining a passive RC filter and a Gm-C based resonator. The latter is built around a capacitively-coupled chopper OTA, which enables a beyond-the-rail input range. Implemented in 65nm CMOS, the proposed CT Δ ΣM achieves 99.2dB SNDR and 100dB DR in a 24kHz BW while consuming only 80.7µW. This results in a state-of-the-art Schreier FoMsNDRof 184dB.