Implementation of a Current Linear Regulator Based on a GaN HEMT for Laser Diode Manipulations

In this study, a gallium nitride (GaN) high electron mobility transistor (HEMT) combined with the operational amplifier was applied to develop a two-level linear regulator (TLLR). Using the TLLR, the operating current of the laser diode can be formed in the constant-current or pulse-width modulation mode to emit the continuous-wave or short-pulsed laser, respectively. When the operating current of the laser diode was operated at the high-frequency PWM, the parasitic elements on the GaN HEMT, laser diodes, print-circuit board (PCB), and power wires influence the rising-edge slope of the laser operating current. In accordance with the physical packages of the GaN HEMT and laser diode, their equivalent circuit model parameters were provided in this study; therefore, the TLLR simulation circuit with its parasitic element was established. The simulation and experiment waveforms can be obtained to confirm the developed TLLR.