GaN HEMT Bias Sequencing and Temperature Compensation Circuit

This application note outlines a bias sequencing circuit that can be used in conjunction with Wolfspeed RF GaN HEMT devices. Under normal operation all Wolfspeed GaN RF devices require a negative gate voltage and positive drain voltage for operation, with the gate voltage having to be applied first to prevent failure. The bias sequencing circuit presented here uses a single DC power supply for both the gate and drain. The circuit topology prevents any failures by not applying drain voltage until a negative gate voltage is ready and DC input voltage is higher than 16V to prevent low voltage issues. The quiescent current (Idq) of the device is adjusted using a potentiometer and the gate bias temperature compensation circuit can be enabled/disabled as needed.