# Design of Nanosecond Pulse Laser Diode Array Driver Circuit for LiDAR
## 1 Introduction  
LiDAR is a sensor module that detects the spatial position and distance of targets by emitting laser beams. In recent years, with the rapid development of autonomous driving, smart homes, machine vision, and other fields, the attention given to LiDAR has been increasing year by year [1; 2; 3; 4]. Currently, the commonly used light source for the light-emitting module of LiDAR is the semiconductor laser diode (LD). A LD has the characteristics of small sizes, low costs, convenience, and is widely used in optoelectronic products [5; 6; 7; 8]. Especially in the fields of optical communication and optical measurement, it is the main component for converting electrical signals at the transmitting end into optical signals. In the field of laser communication, semiconductor laser diodes are the main components for converting electrical signals at the transmitting end into optical signals, and almost all optical transmitters use LDs [6; 9; 10; 11]. In the field of optical measurement, the LD is widely used in laser ranging, laser scanning, and LiDAR [6; 12; 13; 14]. In recent years, due to the rise of autonomous driving technology, LiDAR has become a research hotspot in the field of measurement. The LD drive circuit is a key technology that affects the detection distance, detection resolution, and scanning rate of LiDAR, and is an important component of the LiDAR system. Pulse LiDAR obtains measurement distances by measuring the time interval between the laser emission signal and the laser echo signal, and usually uses a time-to-digital converter (TDC) for TOF measurement [15; 16; 17]. As the core circuit in TOF LiDAR, the design of the pulse laser emission circuit is particularly important. High-power pulse lasers can achieve long-distance measurement, but to ensure the safety of human eyes, the average output power of the laser needs to be limited. To increase the measurementdistance and ensure the safety of human eyes, it is necessary to increase the pulse laser emission power while reducing the pulse width. The design of the LD drive circuit is essentially the design of a pulse power system. The working principle of a LD drive circuit is to apply a certain control level signal to drive the LD to work, convert the electrical energy into laser energy, emit it into space, generate emission on the target, and measure the echo. Due to the power limitation of LDs and in order to protect human eyes from laser damage, LDs can only work under very short pulse (low duty cycle) conditions, which also puts forward the same requirements for the drive circuit. Extremely short pulses and high power are the keys to the design of a LD drive circuit. The LD drive circuit is a key component in the laser radar system, and its performance directly affects the final detection performance of the entire LiDAR system. The pulse laser emission circuit is essentially a device that converts electrical pulses into optical pulses. Its performance parameters mainly include the peak power, pulse width, repetition frequency, etc. The parameters of the emission circuit directly affect the performance of the laser radar system [18; 19]. A higher peak power, narrower pulse width and higher repetition frequency are the design goals of the circuit. The peak power is limited by the power MOSFET switches. Compared to the traditional silicon MOSFET, GaN MOSFET exhibits faster switching frequencies and smaller equivalent series resistances (ESR), making them highly suitable for high-speed, high-power applications. The advent of GaN MOSFET has enhanced the peak power of pulsed LDs [20]. Narrow pulse generation circuits represent another approach to boost the peak power under limited average power conditions. Currently, the output optical pulses of the pulsed LiDAR have evolved from microseconds to nanoseconds [21; 22]. In 2018, [PERSON] et al. utilized GaN MOSFET to generate a current with a peak value exceeding 35 A and a pulse width shorter than 4 ns [23].