Transformer coupled FET drive circuit
AssigneePeco II, Inc.
InventorKenneth Andrew Wallace
Life of this patent
Estimating the term…
Abstract
A FET drive circuit is disclosed. The disclosed drive circuit develops a unipolar voltage from a bi-polar source voltage and facilitates fast turn-off of the driven FET. Preferably, the drive circuit includes a first diode having a first reverse recovery time, a transistor, and a second diode having a second reverse recovery time which is longer than the first reverse recovery time.
Claims24
For use with a transformer driven by a bi-polar source voltage and having a primary winding and a secondary winding, a FET drive circuit comprising:
- a FET having a gate, a drain and a source;
- a first diode having a first terminal coupled to a first terminal of the secondary winding and a second terminal coupled to the gate of the FET, the first diode having a first reverse recovery time;
- a transistor having a base, an emitter and a collector, the emitter of the transistor being coupled to the gate of the FET, the collector of the transistor being coupled to the source of the FET;
- and,
- a second diode having a first terminal coupled to the first terminal of the first diode and a second terminal coupled to the base of the transistor, the second diode having a second reverse recovery time, the second reverse recovery time being longer than the first reverse recovery time.
For use with a transformer driven by a bi-polar source voltage and having a primary winding and a secondary winding, a FET drive circuit comprising:
- a FET having a gate and first and second terminals;
- a transistor coupled between the gate and one of the first and second terminals of the FET, the transistor having a control terminal;
- a first diode coupled to permit current flow to the gate of the FET when a voltage at a first terminal of the secondary winding of the transformer has a first polarity, and to block current flow away from the gate of the FET when the voltage at the first terminal of the secondary winding has a second polarity opposite the first polarity, the first diode having a reverse recovery time;
- and
- a second diode having a reverse recovery time greater than the reverse recovery time of the first diode, the second diode being coupled to block current flow away from the control terminal of the transistor when the voltage at the first terminal of the secondary winding switches from the first polarity to the second polarity and after expiration of the reverse recovery time associated with the second diode.
For use with a FET having a gate, a drain and a source, and with a transformer driven by a bi-polar source voltage and having a primary winding and a secondary winding, a FET drive circuit comprising:
- a first diode coupled to the gate of the FET and having a first reverse recovery time;
- a transistor coupled between the gate and the source of the FET;
- and,
- a second diode coupled to the base of the transistor, the second diode having a second reverse recovery time, the second reverse recovery time being longer than the first reverse recovery time.
For use with a FET having a gate and first and second terminals, and a transformer driven by a bi-polar source voltage and having a primary winding and a secondary winding, a FET drive circuit comprising:
- a transistor coupled between the gate and one of the first and second terminals of the FET, the transistor having a control terminal;
- a first diode coupled to permit current flow to the gate of the FET when a voltage at a first terminal of the secondary winding of the transformer has a first polarity, and to block current flow away from the gate of the FET when the voltage at the first terminal of the secondary winding has a second polarity opposite the first polarity, the first diode having a reverse recovery time;
- and
- a second diode having a reverse recovery time greater than the reverse recovery time of the first diode, the second diode being coupled to block current flow away from the control terminal of the transistor when the voltage at the first terminal of the secondary winding switches from the first polarity to the second polarity and after expiration of the reverse recovery time associated with the second diode.
Dependencies are inferred from the claim text.