An adjustable amplitude and pulsewidth laser modulation driver with active feedback for QKD experiments This paper presents a laser modulation driver using active feedback in a 130nm CMOS process. The driver is designed for laser modulator in quantum key distribution (QKD) experiments. The laser modulator requires a drive signal with adjustable amplitude and pulsewidth. We employ a delayadjustable delay chain and a multistage amplifier with active feedback to provide a current pulse signal with an adjustable pulsewidth from 110 ps to 3.3 ns and an amplitude adjustment range of 0 mA to 14.4 mA to drive the laser modulation. By employing the active feedback, the risingfalling edge of the output current in the proposed circuit can reach 70 ps, while the data rate is up to 625 Mbs. The post layout simulation results indicate that the modulation driver can meet the requirements of the QKD experiments.

An ASIC for Discriminating Single Photon Detector Signal of HighSpeed Quantum Key Distribution System An ASIC is presented in this paper for discriminating signal from single photon detector (SPD) of highspeed quantum key distribution (QKD) system. The circuit is designed in 130 nm CMOS process. It receives and discriminates a small voltage pulse from a SPD, coinciding with a trigger signal and outputs the effective signal to next stage of QKD system. The pulse width of the voltage signal from SPD is less than 400 ps. The circuit mainly consists of bandgap reference, high speed comparator, delay chain and current mode logic (CML) driver. It should operate at a speed of 1.25 GHz. This work integrate all the frontend electronics for SPD into a chip. The area, stray capacitance and power consumption of the whole circuit are reduced. And then the whole receiver of QKD system can be integrated into a chip to improve performance.