A PVT Insensitive Vernier-Based Time-to-Digital Converter With Extended Input Range and High Accuracy

A monolithic Vernier-based time-to-digital converter (TDC) with 37.5 ps time resolution and theoretically unlimited input range has been integrated in TSMC 0.35-mum standard 2P4M CMOS technology. Since the proposed circuit utilizes a single-stage Vernier delay line (VDL) for both coarse and fine measurements, no other interpolation circuit is required. The operation frequencies of the single-stage Vernier delay line are stabilized against process, voltage and temperature (PVT) variations by dual phase-locked loops. The proposed TDC successfully eliminates the element mismatch, input range limitation, external bias adjustment and complicated calibration problems. The measured differential nonlinearity is plusmn0.2 LSB, and the measured integral nonlinearity is plusmn0.35 LSB. The power consumption is 150 mW at 100 k samples/s full conversion speed, and the chip size is as small as 0.222 mm². All the packaged chips were tested to be fully functional over -40degC to 100degC ambient temperature range and 3.0 V to 3.9 V supply voltage range with extremely low resolution variations