Patent ID: 8593211

Claim:
An apparatus, comprising: a first gallium nitride field effect transistor (GaN FET); a first driver coupled to a gate of the first GaN FET; an anode of a capacitor coupled to an output of a driver and a source of the first GaN FET; a diode having a cathode coupled to the cathode of the capacitor; and a bootstrap capacitor clamp (BCC) controller, including: a field effect transistor (FET) coupled to an anode of the diode; and a comparator coupled to a gate of the FET, the comparator configured to receive as inputs: a) a signal representative of an input voltage (VDRV) applied to the FET; b) a ground; c) a boot signal representative of a voltage at the anode of the capacitor (Boot); and d) a signal representative of a Voltage at the source of the first GaN FET, wherein the BCC controller is configured to compare: a) a difference of: i) the VDRV and the GND, to generate a first comparison signal, to b) a difference of ii) the Boot and the source of the first GaN FET, to generate a second comparison signal; wherein the BCC controller is further configured to maintain a relationship between the first comparison signal and the second comparison signal base on the comparison, and wherein the BCC controller is further configured to drive a gate output signal to the first GaN FET to maintain this relationship.