An 8bit, 2.6ps two-step TDC in 65nm CMOS employing a switched ring-oscillator based time amplifier

An 8bit two-step time-to-digital converter (TDC) with a novel digital switched ring-oscillator based time amplifier (TA) is demonstrated in 65nm CMOS. The proposed TA achieves a predictable and programmable gain without requiring any calibration. The implemented 8bit two-step TDC with a 16x TA gain achieves a time resolution of 2.6ps at 80MS/s conversion rate while consuming 2mW. The measured DNL and INL are 1.84LSB and 2.36LSB, respectively. The TDC area is 0.07mm².