A 1.65mW 0.16mm² Dynamic Zoom-ADC with 107.5dB DR in 20kHz BW

Abstract

Audio codecs for automotive applications and smartphones require up to five stereo channels to achieve effective acoustic noise and echo cancellation, thus demanding ADCs with low power and minimal die area. Zoom-ADCs should be well suited for such applications, since they combine compact and energy-efficient SAR ADCs with low-distortion ΔΣ ADCs to simultaneously achieve high energy efficiency, small die area, and high linearity [1,2]. However, previous implementations were limited to the conversion of quasi-static signals, since the two ADCs were operated sequentially, with a coarse SAR conversion followed by, a much slower, fine ΔΣ conversion. This work describes a zoom-ADC with a 20kHz bandwidth, which achieves 107.5dB DR and 104.4dB SNR while dissipating 1.65mW and occupying 0.16mm2. A comparison with recent state-of-the-art ADCs with similar resolution and bandwidth [3-7] shows that the ADC achieves significantly improved energy and area efficiency. These advances are enabled by the use of concurrent fine and coarse conversions, dynamic error-correction techniques, and an inverter-based OTA.