An 8-bit I/O-sized ADC with second-order TDC and MOM capacitor voltage-to-time converter

We present an I/O-sized second-order analog to digital converter (ADC) combined with a time-to-digital converter (TDC) and a voltage-to-time converter (VTC). Our proposed VTC is optimized for metal-oxide-metal (MOM) capacitances, and is charged to the MOM capacitances by an input voltage. In a standard 65-nm CMOS process, an SNR of 50 dB (8 bits) is achievable at an input signal frequency of 78 kHz and a sampling rate of 20 MHz, where the respective area and power are 6468 mm² and 509 μW. The active area of the proposed ADC is smaller than an I/O buffer. The proposed ADC is useful as an ADC I/O.