A 280μW audio continuous-time ΔΣ modulator with 103dB DR and 102dB A-Weighted SNR

Abstract

An optimally designed FIR feedback DAC is used in a third order, single bit continuous-time delta sigma modulator to reduce power dissipation and jitter sensitivity. The loop filter is carefully stabilized for the delay added by the FIR DAC. A current reuse two stage feedforward compensated opamp minimizes current consumption in the first integrator. The efficacy of our techniques is borne out by measurements from a 17 bit audio converter designed in a 0.18 μm CMOS technology. It achieves 103 dB dynamic range, 102 dB A-Weighted SNR and 106 dB SFDR in a 24 kHz bandwidth and dissipates 280 μW from a 1.8 V supply.