Since the 1990s, there has been a dramatic interest in quantum communication. Free-space quantum communication is being developed to ultra-long distance quantum experiment, which requires higher electronics performance, such as time measurement preci
sion, data-transfer rate, and system integration density. As part of the ground station of quantum experiment satellite that will be launched in 2016, we specifically designed a compact PCI-based multi-channel electronics system with high time-resolution, high data-transfer-rate. The electronics performance of this system was tested. The time bin size is 23.9ps and the time precision root-mean-square (RMS) is less than 24ps for 16 channels. The dead time is 30ns. The data transfer rate to local computer is up to 35 MBps, and the count rate is up to 30M/s. The system has been proven to perform well and operate stably through a test of free space quantum key distribution (QKD) experiment.
A high precision and high resolution time-to-digital converter (TDC) implemented in a 40 nm fabrication process Virtex-6 FPGA is presented in this paper. The multi-chain measurements averaging architecture is used to overcome the resolution limitatio
n determined by intrinsic cell delay of the plain single tapped-delay chain. The resolution and precision are both improved with this architecture. In such a TDC, the input signal is connected to multiple tapped-delay chains simultaneously (the chain number is M), and there is a fixed delay cell between every two adjacent chains. Each tapped-delay chain is just a plain TDC and should generate a TDC time for a hit input signal, so totally M TDC time values should be got for a hit signal. After averaging, the final TDC time is obtained. A TDC with 3 ps resolution (i.e. bin size) and 6.5 ps precision (i.e. RMS) has been implemented using 8 parallel tapped-delay chains. Meanwhile the plain TDC with single tapped-delay chain yields 24 ps resolution and 18 ps precision.
