US 11,837,946 B2
Bootstrap power supply circuit
Santosh Sharma, Laguna Niguel, CA (US); and Daniel Marvin Kinzer, El Segundo, CA (US)
Assigned to Navitas Semiconductor Limited, Dublin (IE)
Filed by Navitas Semiconductor Limited, Dublin (IE)
Filed on May 16, 2022, as Appl. No. 17/745,700.
Application 17/745,700 is a continuation of application No. 16/828,747, filed on Mar. 24, 2020, granted, now 11,362,577.
Application 16/828,747 is a continuation of application No. 16/375,729, filed on Apr. 4, 2019, granted, now 10,601,302, issued on Mar. 24, 2020.
Prior Publication US 2022/0278605 A1, Sep. 1, 2022
Int. Cl. H02M 3/158 (2006.01); H02M 1/08 (2006.01); H03K 17/081 (2006.01)
CPC H02M 1/08 (2013.01) [H02M 3/1588 (2013.01); H03K 17/08104 (2013.01); H03K 2217/0063 (2013.01); H03K 2217/0072 (2013.01); H03K 2217/0081 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of operating a gallium nitride (GaN) half-bridge circuit, the method comprising:
providing a GaN half-bridge circuit having a GaN low-side power transistor and a GaN high-side power transistor coupled to the GaN low-side power transistor at a switch node;
providing a bootstrap transistor coupled between a first ground referenced power supply and a floating power supply terminal, a bootstrap transistor drive circuit with an output terminal that is coupled to the bootstrap transistor, and a bootstrap capacitor coupled between the floating power supply terminal and the switch node;
wherein the bootstrap transistor drive circuit comprises a drive stage that is coupled between the first ground referenced power supply and a second ground referenced power supply;
wherein the bootstrap transistor drive circuit further comprises a voltage generator arranged to generate a voltage at the second ground referenced power supply;
wherein the voltage at the second ground referenced power supply is set, by the voltage generator, to a first voltage value when the GaN low-side power transistor is turned on to a conductive state and is set, by the voltage generator, to a second voltage value when the GaN low-side power transistor is in a non-conductive state;
wherein the first voltage value is higher than the second voltage value;
turning on the bootstrap transistor, by the bootstrap transistor drive circuit, when the GaN low-side power transistor is turned on to a conductive state, causing a current to flow from the first ground referenced power supply to the floating power supply terminal;
charging the bootstrap capacitor when the GaN low-side power transistor is in the conductive state;
turning off the bootstrap transistor, by the bootstrap transistor drive circuit, when the GaN low-side power transistor is in a non-conductive state; and
supplying, by the bootstrap capacitor, a floating power supply for driving the GaN high-side power transistor when the GaN low-side power transistor is in the non-conductive state.