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

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 92.5dB dynamic range in a 24 kHz bandwidth and dissipates 110 μW from a 1.8 V supply. The Figure of Merit (FOM) of this modulator is 66.5fJ/level1. © 2009 IEEE.