High-precision time measurement electronics using the bandpass sampling method

Waveform digitization at sampling rates up to several giga-samples per second is one of the approaches to achieve high-precision time measurements. In recent years, achieving high precision at lower sampling rates has emerged as a significant research topic. In this article, we focus on time measurement electronics, in which the bandpass sampling method is applied to obtain high precision at a sampling rate of roughly 100 MSps. An analog front-end circuit is designed, in which the input pulse signal is bandpass-filtered and amplified before sampling. A pipelined real-time time extraction algorithm is designed using the techniques of interpolation and cross correlation. A 1024-point fast Fourier transform algorithm is adopted to implement the cross correlation operation. Four time measurement channels are implemented in a mid-range field-programmable gate array, and the measurement rate of 116 kHz is achieved. Tests are conducted to evaluate the performance of the timing system. The typical RMS precision is better than 0.4 ps.