A 110µW single bit audio continuous-time oversampled converter with 92.5 db dynamic range

Abstract

The first integrator in a low pass continuous-time ΔΣ modulator normally consumes significant power due to stringent noise and linearity requirements, especially in single-bit designs. We introduce the “assisted opamp integrator” that addresses this problem. The efficacy of our technique is borne out by measurements from a 15 bit audio converter designed in a 0.18 µm CMOS technology. It achieves 92.5 dB dynamic range in a 24 kHz bandwidth and dissipates 110 µW from a 1.8V supply. The Figure of Merit (FOM) of this modulator is 66.5 fJ/level.