A 9 bit, 1.12 ps Resolution 2.5 b/Stage Pipelined Time-to-Digital Converter in 65 nm CMOS Using Time-Register

In this paper, a 2.5 b/stage pipelined time-to-digital converter (TDC) is presented. For pipelined operation, a novel time-register is proposed which is capable of storing, adding and subtracting time information with a clock signal. Together with a pulse-train time-amplifier, a 9-bit synchronous pipelined TDC is implemented, which consists of three 2.5 b/stage TDCs and a 3 b delay-line TDC. A prototype chip fabricated in 65 nm CMOS process achieves 1.12 ps of time resolution at 250 MS/s while consuming 15.4 mW. Compared to other high-resolution state-of-the-art TDCs, the proposed pipelined TDC achieves the best figure-of-merit (FoM) without any calibration.