Active driving of normally on, normally off cascoded configuration devices through asymmetrical cmos

Abstract

Disclosed is a method of controlling a High Electron Mobility Transistor (HEMT) through a cascode circuit, the cascode circuit including first and second switches, a capacitor connected to a source of the first switch, a source of the HEMT being connected to the drain of the first switch, and a controller for controlling the first and second switches. The method is achieved by defining state A, where the first switch is controlled to be OFF resulting in the HEMT being OFF and the second switch is controlled to be ON allowing the capacitor to be charged and stabilizing the drain voltage of the HEMT at around the HEMT gate threshold voltage. The method further defines state B, where the first switch is controlled to be ON resulting in the HEMT being ON and the second switch is controlled to be OFF almost all the time, thereby preserving the charge stored in the capacitor. Moreover, the method provides transitioning from state A to state B to turn the HEMT ON; and transitioning from state B to state A to turn the HEMT OFF, wherein the first switch is switched-OFF and the second switch is switched-ON allowing for quicker charge of the output capacitance of the first switch from the capacitor to keep the HEMT OFF.