A 590 µW, 106.6 dB SNDR, 24 kHz BW Continuous-Time Zoom ADC with a Noise-Shaping 4-bit SAR ADC

This paper presents a continuous-time zoom ADC for audio applications. It combines a 4-bit noise-shaping coarse SAR ADC and a fine delta-sigma modulator with a tail-resistor linearized OTA for improved linearity, energy efficiency, and handling of out-of-band interferers compared to previous designs. In 160 nm CMOS, the prototype chip occupies 0.36 mm ² , achieves 107.2 dB SNR, 106.6 dB SNDR, and 107.3 dB dynamic range in a 24 kHz bandwidth while consuming 590 µW from a 1.8 V supply. This translates into a Schreier figure-of-merit (FoMs) of 183.4 dB and a FoM SNDR of 182.7 dB.