15.4b Incremental Sigma-Delta Capacitance-to-Digital Converter with Zoom-in 9b Asynchronous SAR


An incremental zoom-in capacitance-to-digital converter (CDC) is proposed. By using a 9b SAR, the OSR can be reduced to only 32, significantly improving conversion energy. We show how the OTA in the SAR is bypassed for the CDC further reducing energy and propose a novel matrix based 512-element unit-cap structure for dynamic element matching. The CDC achieves 94.7dB SNR and 33.7$μ$W power consumption with 175fJ/conv-step at 1.4V supply.

2014 Symposium on VLSI Circuits Digest of Technical Papers
Kaiyuan Yang
Assistant Professor of ECE