Yang, Puqing; Zhang, Zhaofeng; Mei, Niansong

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS

2022, 69, 1549-7747

Yang, Puqing; Zhang, Zhaofeng; Mei, Niansong

In this brief, we proposed a small area, high precision, and high energy efficiency single-ended capacitance-to-digital converter (CDC). The circuit incorporates a Delta Sigma CDC and a SAR CDC. The SAR CDC is a coarse CDC which determines the measurement range of capacitance, considering the area consumption, single-ended SAR CDC is adopted. To get a high resolution, inverter-based correlated-double-sampling (CDS) circuit is employed in the Delta Sigma modulation loop. The test chip is fabricated in a 180-nm CMOS process and the core occupies an area of 0.15mm(2). The circuit achieves an rms resolution of 186aF at a 4pF input capacitor, the power consumption is 4.1 mu W in SAR phase with a 100kHz sampling rate and 23.2 mu W in Delta Sigma phase with a 400 kHz sampling rate.