A 10-bit, 3 ps rms precision time-to-digital converter for diffuse optical tomography measurements

This paper reports the design of a 10-bit time-to-digital converter (TDC) based on Vernier residues amplification dedicated to diffuse optical tomography (DOT) measurements. The key benefits of the proposed architecture is to keep a low jitter, hence delivering high TDC precision, and allowing reaching high resolution regardless of the process technology. Experimental results show that the TDC achieves a timing resolution of 12.3 ps and a precision of 3 ps rms in a 12.5 ns window. Moreover, the TDC shows differential and integral nonlinearities (DNL and INL) of 0.39 and 1.35 LSB rms respectively. The TDC, implemented in 130 nm CMOS technology, occupies a total silicon area of 1.83 × 2.23 mm² including interconnect pads and consumes 4.8 mW excluding the digital I/O. Such TDC can find useful applications in biomedicai imaging systems and in all-digital phase-locked loop (D-PLL).