Gate drive circuit

Patent metadata

Field	Value
Publication number	US-2017288657-A1
Application number	US-201715474223-A
Country	US
Kind code	A1
Filing date	Mar 30, 2017
Priority date	Mar 30, 2016
Publication date	Oct 5, 2017
Grant date	—

Abstract

A gate drive circuit has a capacitor and a gate drive voltage source connected in series with a gate terminal of a voltage-driven switching device. The gate drive source voltage feeds, as a gate drive voltage, a voltage higher than the sum of the voltage applied to a gate-source parasitic capacitance of the switching device when the switching device is in a steady ON state and the voltage applied to, of any circuit component interposed between the gate drive voltage source and the gate terminal of the switching device, a circuit component other than the capacitor (such as an upper transistor forming the output stage of the driver). No other circuit component (such as a resistor connected in parallel with the capacitor) is essential but the capacitor as the sole circuit component to be directly connected to the gate terminal of the switching device.

First claim

What is claimed is:

1 . A gate drive circuit, comprising:
a first capacitor and a first gate drive voltage source connected in series with a gate terminal of a switching device of a voltage-driven type, wherein the first gate drive voltage source is configured to feed, as a first gate drive voltage, a voltage higher than a sum of a voltage applied to a gate-source (emitter) parasitic capacitance of the switching device when the switching device is in a steady ON state and a voltage applied to, of any circuit component interposed between the first gate drive voltage source and the gate terminal of the switching device, a circuit component other than the first capacitor.

2 . The gate drive circuit of claim 1 , wherein
the first gate drive voltage has a voltage value higher than a rated gate-source (gate-emitter) DC voltage of the switching device but lower than a rated gate-source (gate-emitter) surge voltage of the switching device, and the voltage applied to the gate-source (emitter) parasitic capacitance of the switching device when the switching device is in the steady ON state is adjusted to be lower than the rated DC voltage.

3 . The gate drive circuit of claim 1 , further comprising:
a first discharger connected in parallel with the first capacitor, the first discharger being configured to discharge the first capacitor when the switching device is OFF.

4 . The gate drive circuit of claim 3 ,
wherein the first discharger includes a first resistor, and the gate drive circuit further comprises a second resistor connected between a gate and a source (emitter) of the switching device.

5 . The gate drive circuit of claim 4 , wherein
let a capacitance value of the first capacitor be Cg, let a capacitance value of the gate-source (emitter) parasitic capacitance observed when the switching device is in the steady ON state be Cgs, let a resistance value of the first resistor be Rg, and let a resistance value of the second resistor be Rgs, then a relationship of Cg:(Cg+Cgs)=(Rg//Rgs):Rg holds.

6 . The gate drive circuit of claim 3 , wherein
the first discharger includes a switch.

7 . The gate drive circuit of claim 3 , further comprising:
a second gate drive voltage source connected to a first gate drive voltage source side of the first discharger.

8 . The gate drive circuit of claim 3 , further comprising:
a second discharger of which a first terminal is connected to the gate terminal of the switching device; and a second gate drive voltage source connected to a second terminal side of the second discharger.

9 . The gate drive circuit of claim 8 , wherein
the second discharger includes a second capacitor.

10 . The gate drive circuit of claim 8 , wherein
the second discharger includes a third resistor.

11 . A gate drive circuit, comprising:
a capacitor and a gate drive voltage source connected in series with a gate terminal of a switching device of a voltage-driven type, wherein the capacitor is a sole circuit component directly connected to the gate terminal of the switching device.

Assignees

• Rohm Co Ltd

Inventors

• Yanagi Tatsuya
• Otake Hirotaka
• Sawada Takashi
• Kitagawa Seiya

Classifications

• H03K17/04 Primary

  Modifications for accelerating switching · CPC title

• H03K17/04123 Primary

  in field-effect transistor switches · CPC title

• H01L29/7805

  Electricity · mapped topic

• H01L29/1608

  Electricity · mapped topic

• H10D62/8325

  Silicon carbide · CPC title