Field programmable gate array time counter with two-stage interpolation

This paper presents a precise time counter with two two-stage interpolators, integrated in a field-programmable gate array device. Interpolation is performed by a single tapped delay line with dual synchronizers in the first stage and a differential tapped delay line in the second stage. The delay-locked loop is used for indirect stabilization of the propagation time of delay elements. The counter has 200 ps resolution over the measurement range of 0-167 ms with the standard measurement uncertainty below 140 ps. A detailed analysis of influence of the flip-flop metastability on the counter accuracy is also presented. (C) American Institute of Physics.