A current pulse generator circuit configured to be monolithically integrated into a single semiconductor die and provide high pulsing frequencies. A first GaN FET transistor controls the charging of a capacitor in a boost converter. A second GaN FET transistor controls the discharging of the capacitor through a load, such as a laser diode, connected to the boost converter. Both GaN FET transistors are preferably enhancement mode GaN FETs and may be integrated into the single semiconductor die, together with gate drivers. The diode in a conventional boost converter circuit can also be implemented in the present invention as a GaN FET transistor, and also integrated into the single semiconductor die.