  The single photon source is an important part of the quantum key distribution
(QKD) system. At present, the single photon source is large in size and complex
in structure for a lot of discrete components which are used. The
miniaturization of the photon source is the tendency of the QKD system. We
integrate all laser driver electronic module into one single ASIC chip, which
can be used to drive the 1550nm DFB laser in random pulse mode and it can
greatly reduce the volume of the single photon source. We present the design of
the chip named LSD2018 and simulation results before the tape-out. The LSD2018
is fabricated with a 130 nm CMOS process and consists of a discriminator, an
adjustable pulse generator, a bandgap reference, an SPI bus, and an
amplitude-adjustable current pulse driver. The electronic random pulse from the
driver can go 20mA to 120mA in amplitude and 400ps to 4ns in pulse width. The
parameters can be set by an SPI bus.
