Patent ID: 10847947

Abstract:
A laser-diode driver for Lidar applications with an output stage comprised of two enhancement mode GaN FETs. The output stage includes a driver GaN FET in a traditional common-source configuration, with the drain connected to the cathode of a laser diode and the source connected to ground. The gate of the driver GaN FET is driven by the source of the second, substantially smaller GaN FET in a source-follower configuration, rather than being driven directly by a pre-driver. The source-follower GaN FET has its drain connected to the drain of the common-source driver GaN FET, similar to a Darlington connection used in bipolar devices. The input drive signal from the pre-driver is applied at the gate of the source-follower GaN FET. The current required to turn on the driver GaN FET is thereby drawn from a main power supply through the laser diode, rather than from the power supply for the pre-driver, improving overall current efficiency.