US 9,755,636 B2 · Insulated gate device discharging

Abstract

A large-power insulated gate switching device (e.g., MOSFET) is used for driving relatively large surges of pulsed power through a load. The switching device has a relatively large gate capacitance which is difficult to quickly discharge. A gate charging and discharging circuit is provided having a bipolar junction transistor (BJT) configured to apply a charging voltage to charge the gate of the switching device where the BJT is configured to also discontinue the application of the charging voltage. An inductive circuit having an inductor is also provided. The inductive circuit is coupled to the gate of the switching device and further coupled to receive the charging voltage such that application of the charging voltage to the inductive circuit is with a polarity that induces a first current to flow through the inductor in a direction corresponding to charge moving away from the gate and such that discontinuation of the application of the charging voltage to the inductive circuit induces a second current flowing through the inductor in the direction corresponding to charge moving away from the gate such that the second current discharges the gate of the switching device. Faster turn off of the switching device is thus made possible and is synchronized to the discontinuation of the charging voltage.

Claims20

Dependent claims

A method of charging and discharging a gate of an insulated gate switching device comprising:

activating a first transistor to apply a charging voltage to charge the gate of the switching device, the first transistor having a driving terminal connected directly to the gate of the switching device to apply said charging voltage, the first transistor further having a driven terminal coupled to a voltage source and a control terminal operable to selectively activate and deactivate the first transistor;
using the first transistor to also apply the charging voltage to an inductive circuit having an inductance, the inductive circuit being coupled to the gate of the switching device, the applying of the charging voltage to the inductive circuit being with a polarity that induces a first current to flow through the inductance in a direction corresponding to charge moving away from the gate;
and
de-activating the first transistor to thereby discontinue the applying of the charging voltage to the inductive circuit and to the gate of the switching device;
wherein the discontinuing of the applying of the charging voltage to the inductive circuit induces a second current to flow through the inductance in the direction corresponding to charge moving away from the gate, the second current operating to discharge the gate of the switching device.

2 more elements

A circuit for charging and discharging a gate of an insulated gate field effect transistor (IGFET), the circuit comprising:

a first transistor configured to apply a charging voltage to charge the gate of the IGFET, the first transistor having a driving terminal connected directly to the gate of the IGFET to apply said charging voltage, the first transistor further having a driven terminal coupled to a voltage source and a control terminal operable to selectively activate and deactivate the first transistor, where deactivation of the first transistor operates to discontinue the application of the charging voltage;
and
an inductive circuit having an inductance, the inductive circuit being coupled to the gate of the IGFET, the inductive circuit being further coupled and configured to receive the charging voltage such that application of the charging voltage to the inductive circuit is with a polarity that induces a first current to flow through the inductance in a direction corresponding to charge moving away from the gate and such that discontinuation of the application of the charging voltage to the inductive circuit induces a second current flowing through the inductance in the direction corresponding to charge moving away from the gate such that the second current discharges the gate of the IGFET.

A combination of an insulated gate field effect transistor (IGFET), a charging and discharging circuit coupled to a gate of the IGFET and a light emitter coupled to be driven by a current flow through the IGFET wherein:

the charging and discharging circuit comprises:
a first transistor configured to apply a charging voltage to charge the gate of the IGFET, the first transistor having a driving terminal connected directly to the gate of the IGFET to apply said charging voltage, the first transistor further having a driven terminal coupled to a voltage source and a control terminal operable to selectively activate and deactivate the first transistor, where deactivation of the first transistor operates to discontinue the application of the charging voltage;
and
an inductive circuit having an inductance, the inductive circuit being coupled to the gate of the IGFET, the inductive circuit being further coupled and configured to receive the charging voltage such that application of the charging voltage to the inductive circuit is with a polarity that induces a first current to flow through the inductance in a direction corresponding to charge moving away from the gate and such that discontinuation of the application of the charging voltage to the inductive circuit induces a second current flowing through the inductance in the direction corresponding to charge moving away from the gate such that the second current discharges the gate of the IGFET;
and wherein
the combination is configured to produce pulses of light having falling edges of durations less than 10 nanoseconds.

3 more elements

Dependencies are inferred from the claim text.

Insulated gate device discharging

Life of this patent

Insulated gate device discharging

Life of this patent

Abstract

Claims20