40 MHz-BW continuous-timeΔΣmodulator with capacitive local feedback and current-sharing OTA

A 40 MHz-bandwidth (BW) 12-bit delta-sigma modulator (DSM) fabricated in 90 nm CMOS is presented. A noise-free capacitive local feedback scheme is proposed for noise transfer function complex zeros generation. Moreover, the operational transconductance amplifiers (OTAs) are implemented with a current-sharing feedforward technique to largely reduce the power and to boost the gain. With a 960 MHz clock frequency and 1.2 V supply, the modulator achieves 74.4 dB dynamic range and 69.7 dB peak signal-to-noise and distortion ratio (SNDR). The DSM FoM is 0.22 pJ/conv, which is among the lowest of the published moderate resolution DSMs in this high-bandwidth range.