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US 8,947,896 B2Granted
Proportional bias switch driver circuit
AssigneeFairchild Semiconductor Corporation
InventorRichard Alan Dunipace
Life of this patent
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Abstract
A switch bias system is provided that includes a bipolar junction transistor (BJT) switch comprising a base, emitter, and collector; a current sense circuit coupled to the emitter, the current sense circuit configured to sense current flow through the emitter of the BJT switch; and a proportional bias circuit configured to generate a bias current to the base of the BJT switch, the bias current set to a fixed proportion of the sensed current flow through the emitter of the BJT switch.
Claims20
A system, comprising:
- a bipolar junction transistor (BJT) switch comprising a base, emitter, and collector;
- an energy storage circuit coupled to said collector of said BJT, said energy storage circuit supplying current flow to said collector of said BJT;
- a current sense circuit coupled to said emitter, said current sense circuit configured to sense current flow through said emitter of said BJT switch;
- and
- a proportional bias circuit configured to generate a bias current to said base of said BJT switch, said bias current set to a fixed proportion of said sensed current flow through said emitter of said BJT switch.
2 more elements
A method, comprising:
- selectively operating a BJT switch to control current flow, said BJT switch comprising a base, emitter, and collector;
- coupling a current sense circuit to said emitter of said BJT directly, or through a series MOSFET, said current sense circuit configured to sense current flow through said emitter of said BJT switch;
- and
- generating a bias current to said base of said BJT switch, said bias current maintained at a fixed proportion of said sensed current flow through said emitter of said BJT switch.
1 more element
An apparatus, comprising:
- a bipolar junction transistor (BJT) switch comprising a base, emitter, and collector;
- a current sense circuit coupled to said emitter, said current sense circuit configured to sense current flow through said emitter of said BJT switch;
- and
- a proportional bias circuit configured to generate a bias current to said base of said BJT switch, said bias current set to a fixed proportion of said sensed current flow through said emitter of said BJT switch.
1 more element
Dependencies are inferred from the claim text.