High voltage zero QRR bootstrap supply

• US 9,667,245 B2
• Filed: 10/07/2015
• Issued: 05/30/2017
• Est. Priority Date: 10/10/2014
• Status: Active Grant

• Current Assignee: Efficient Power Conversion Corporation
• Original Assignee: Efficient Power Conversion Corporation
• Inventors: De Rooij, Michael A., Strydom, Johan T., Reusch, David C.
• Primary Examiner(s): Puentes, Daniel
• Application Number:
  US14/877,613
• Publication Number:
  US 20160105173A1
• Time in Patent Office: 601 Days
• CPC Class Codes: H03K 17/04206 in field-effect transistor switches
• CPC Class Codes: H03K 17/165 by feedback from the output circuit to the control circuit
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor
• CPC Class Codes: H03K 19/017509 Interface arrangements
• CPC Class Codes: H03K 2217/0063 High side switches, i.e. the higher potential [DC] or life wire [AC] being directly connected to the switch and not via the load
• CPC Class Codes: H03K 2217/0072 Low side switches, i.e. the lower potential [DC] or neutral wire [AC] being directly connected to the switch and not via the load
• CPC Class Codes: H03K 2217/0081 Power supply means, e.g. to the switch driver

Abstract

An electrical circuit arranged in a half bridge topology. The electrical circuit includes a high side transistor; a low side transistor; a gate driver and level shifter electrically coupled to a gate of the high side transistor; a gate driver electrically coupled to a gate of the low side transistor; a capacitor electrically coupled in parallel with the gate driver and level shifter; a voltage source electrically coupled to an input of the gate driver and level shifter and an input of the gate driver; and, a bootstrap transistor electrically coupled between the voltage source and the capacitor. A GaN field-effect transistor is synchronously switched with a low side device of the half bridge circuit.

Claims

1. A method of bootstrapping an electrical circuit arranged in a half bridge topology, wherein the electrical circuit comprises a high side transistor, a low side transistor, a gate driver and level shifter electrically coupled to a gate of the high side transistor, a capacitor electrically coupled in parallel with the gate driver and level shifter, a voltage source electrically coupled to an input of the gate driver and level shifter, and a bootstrap GaN field-effect transistor electrically coupled between the voltage source and the capacitor, wherein the method comprises:

synchronously switching the bootstrap GaN field-effect transistor with the low side transistor of the half bridge circuit.

2. The method of claim 1, wherein the low side transistor is a GaN field-effect transistor.

3. The method of claim 1, wherein the bootstrap GaN field-effect transistor is a depletion mode transistor with its gate in electrical communication with the output of a gate driver in electrical communication with the gate of the low side transistor.

4. The method of claim 2, wherein a voltage across a source and a drain of the bootstrap GaN field-effect transistor is equal to a voltage across a source and a drain of the low side GaN field-effect transistor.

5. The method of claim 4, wherein the voltage across a gate and the source of the low side GaN field-effect transistor is zero (0) Volts, and the voltage across a gate and the source of the bootstrap GaN field-effect transistor is negative five (−

5) Volts when values of a drain current are worst case.

6. The method of claim 1, wherein the bootstrap GaN field-effect transistor is an unclamped enhancement mode transistor and an additional voltage is supplied to the bootstrap GaN field-effect transistor to increase and overcome the voltage drop across the body diode of the bootstrap GaN field-effect transistor.

7. The method of claim 1, wherein the bootstrap GaN field-effect transistor is an enhancement mode transistor that is clamped with a Zener diode that is in parallel with the capacitor and the gate driver and level shifter.

8. The method of claim 7, wherein the Zener diode clamps the voltage across the capacitor to a safe level for the low side transistor.

9. The method of claim 7, wherein a resistor is connected in series between a drain of the enhancement mode transistor and the Zener diode.

10. The method of claim 1, wherein a diode is electrically coupled between a driving voltage and a gate of the bootstrap GaN field-effect transistor and, a capacitor is electrically coupled between a gate of the bootstrap GaN field-effect transistor and an output of a gate driver for the low side transistor.