Operation of double-base bipolar transistors with additional timing phases at switching transitions
AssigneeIdeal Power Inc.
InventorsWilliam C. Alexander, Richard A. Blanchard
Life of this patent
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Abstract
Methods and systems for operating a double-base bidirectional power bipolar transistor. Two timing phases are used to transition into turn-off: one where each base is shorted to its nearest emitter/collector region, and a second one where negative drive is applied to the emitter-side base to reduce the minority carrier population in the bulk substrate. A diode prevents reverse turn-on while negative base drive is being applied.
Claims9
A method for operating a bidirectional bipolar power transistor which has two distinct p-type emitter/collector regions on opposite faces of a n-type semiconductor die, and two distinct n-type base contact regions on the opposite faces of the die, comprising:
- 1) in a transistor-ON timing phase, when minimal voltage drop is desired, biasing a first one of the base contact regions, which is closest to whichever of the emitter/collector regions is more positive at the moment, to a voltage which causes bipolar conduction, to thereby reduce the voltage drop between the two emitter/collector regions;
- and thereafter
- 2) in a first pre-turnoff timing phase, shorting each of the base contact regions to the respectively nearest one of the emitter/collector regions, to thereby increase the voltage drop between the two emitter/collector regions;
- and thereafter
- 3) in a second pre-turnoff timing phase, biasing the second base contact regions negative with respect to its nearest emitter/collector region, to thereby reduce the minority carrier concentration in the bulk base region.
A method for operating a bidirectional bipolar power transistor which has two distinct p-type emitter/collector regions on opposite faces of a n-type semiconductor die, and two distinct n-type base contact regions on the opposite faces of the die, comprising, when a first one of the emitter/collector regions is more positive than a second one of the emitter/collector regions:
- 0) in a diode-ON timing phase, shorting a first one of the base contact regions to the first emitter/collector region, which is the nearest thereto, to thereby initiate conduction between the two emitter/collector regions;
- and thereafter
- 1) in a transistor-ON timing phase, when minimal voltage drop is desired, biasing the first base contact region to a voltage which causes bipolar conduction, to thereby reduce the voltage drop between the two emitter/collector regions;
- and thereafter
- 2) in a first pre-turnoff timing phase, shorting each of the base contact regions to the respectively nearest one of the emitter/collector regions, to thereby increase the voltage drop between the two emitter/collector regions;
- and thereafter
- 3) in a second pre-turnoff timing phase, biasing the second base contact regions negative with respect to the second emitter/collector region;
- and thereafter
- 4) shorting the second base contact region to the second emitter/collector region, to keep the device turned off.
A method for operating a bidirectional bipolar power transistor which has two distinct p-type emitter/collector regions on opposite faces of a n-type semiconductor die, and two distinct n-type base contact regions on the opposite faces of the die, comprising:
- 1) in a transistor-ON timing phase, when minimal voltage drop is desired, biasing a first one of the base contact regions, which is closest to whichever of the emitter/collector regions is more positive at the moment, to a voltage which causes bipolar conduction, to thereby reduce the voltage drop between the two emitter/collector regions;
- and thereafter
- 2) in a first pre-turnoff timing phase, shorting each of the base contact regions to the respectively nearest one of the emitter/collector regions, to thereby increase the voltage drop between the two emitter/collector regions;
- and thereafter
- 3) in a second pre-turnoff timing phase, biasing a second one of the base contact regions negative with respect to its nearest emitter/collector region, to thereby reduce the minority carrier concentration in the bulk base region;
- and
- during step 3), using a diode to block current which would tend to turn on conduction in a direction opposite to that of step 1).
Dependencies are inferred from the claim text.