0.3-V $RC$ -to-Digital Converter Using a Negative Charge-Pump Switch

This brief proposes a 0.3-V resistance and capacitance-to-digital converter (RCDC) using a negative charge-pump switch. The proposed RCDC operates at a subthreshold supply voltage by using the negative charge-pump switch, which turns on a precharge pMOS switch with a negative supply voltage. It converts resistance or capacitance to digital signals. The proposed RCDC was fabricated using a 65-nm CMOS process. It achieves ENOBs of 10.6 bits for the resistance of 1-100kΩ and the capacitance of 10 pF-10 nF, which correspond to figure-of-merits (FoMs) of 3.03 pJ/step and 2.54 pJ/step, respectively, at the supply voltage of 0.3 V.