A high precision time-to-digital converter based on multi-phase clock implemented within Field-Programmable-Gate-Array

In this paper, the design of a coarse-fine interpolation Time-to-Digital Converter （TDC） is implemented in an ALTERA＇s Cyclone FPGA. The carry-select chain performs as the tapped delay line. The Logic Array Block （LAB） having a propagation delay of 165 ps in the chain is synthesized as delay cell. Coarse counters triggered by the global clock count the more significant bits of the time data. This clock is also fed through the delay line, and LABs create the copies. The replicas are latched by the tested event signal, and the less significant bits are encoded from the latched binary bits. Single-shot resolution of the TDC can be 60 ps. The worst Differential Nonlinearity （DNL） is about 0.2 Least Significant Bit （LSB, 165 ps in this TDC module）, and the Integral Nonlinearity （INL） is 0.6 LSB. In comparison with other architectures using the synchronous global clock to sample the taps, this architecture consumed less electric power and logic cells, and is more stable.