US4877982A
Expired / Lapsed
US
⏱️ 0.0 years remaining
MOSFET turn-on/off circuit
Assignee: Fairchild Korea Semiconductor Ltd
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Filing: 1989-01-23
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Granted: 1989-10-31
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Expires: 2009-01-23
Abstract
Abstract A dual current source MOSFET turn-on/off circuit includes a high gain PNP transistor as a turn-off current source and a high gain NPN transistor as a turn-on current source for a P-channel MOSFET. A switch in the base circuit of the NPN transistor turns on the NPN transistor current source which overpowers the PNP transistor current source. The net current charges the MOSFET gate-to-source capacitance which, upon reaching a threshold voltage, turns the MOSFET on. When the switch is opened, the PNP transistor current source discharges the gate-to-source capacitance, turning off the MOSFET. The circuit provides almost constant power dissipation independent of input voltage and a constant turn-on/off time independent of input voltage.
Inventors
- 👤 Charles S. Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:51
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/687; H03K17/6877; H02; H02M; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H03K17/04; H03K17/041; H03K17/0412; H03K17/04123
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
123 words
A dual current source MOSFET turn-on/off circuit comprising: a MOSFET connected between a voltage source and a load; a turn-off current source comprising a first high gain bipolar transistor connected to a gate electrode of said MOSFET; a turn-on current source comprising a second high gain bipolar transistor connected in series with said first bipolar transistor; and switch means connected to a base electrode of said second bipolar transistor for turning said second bipolar transistor on and off, said turn-on current source overpowering said turn-off current source when said second bipolar transistor is turned on to charge a gate-to-source capacitance of said MOSFET and said turn-off current source discharging said gate-to-source capacitance of said MOSFET when said second bipolar transistor is turned off.
Claim 2
Dependent Claim
123 words
A dual current source MOSFET turn-on/off circuit comprising: a MOSFET connected between a voltage source and a load; a turn-off current source comprising a first high gain bipolar transistor connected to a gate electrode of said MOSFET; a turn-on current source comprising a second high gain bipolar transistor connected in series with said first bipolar transistor; and switch means connected to a base electrode of said second bipolar transistor for turning said second bipolar transistor on and off, said turn-on current source overpowering said turn-off current source when said second bipolar transistor is turned on to charge a gate-to-source capacitance of said MOSFET and said turn-off current source discharging said gate-to-source capacitance of said MOSFET when said second bipolar transistor is turned off.
Claim 3
Dependent Claim
67 words
The dual current source MOSFET turn-on/off circuit according to claim 1 wherein said turn-off current source comprises: base bias means connected to a base electrode of said first bipolar transistor for setting a base potential and providing temperature compensation for said first bipolar transistor; and means connected to an emitter electrode of said first bipolar transistor for setting a turn-off current level of said first bipolar transistor.
Claim 4
Dependent Claim
67 words
The dual current source MOSFET turn-on/off circuit according to claim 1 wherein said turn-on current source comprises: base bias means connected to a base electrode of said second bipolar transistor for setting a base potential and providing temperature compensation for said second bipolar transistor; and means connected to an emitter electrode of said second bipolar transistor for setting a turn-on current level of said second bipolar transistor.
Claim 5
Dependent Claim
124 words
The dual current source MOSFET turn-on/off circuit according to claim 1 wherein said turn-off current source comprises: base bias means connected to a base electrode of said first bipolar transistor for setting a base potential and providing temperature compensation for said first bipolar transistor; and means connected to an emitter electrode of said first bipolar transistor for setting a turn-off current level of said first bipolar transistor; and wherein said turn-on current source comprises: base bias means connected to a base electrode of said second bipolar transistor for setting a base potential and providing temperature compensation for said second bipolar transistor; and means connected to an emitter electrode of said second bipolar transistor for setting a turn-on current level of said second bipolar transistor.
Claim 6
Dependent Claim
35 words
The dual current source MOSFET turn-on/off circuit according to claim 4 wherein said MOSFET is a P-channel MOSFET, said first bipolar transistor is a PNP transistor, and said second bipolar transistor is an NPN transistor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-30 | 1993-05-01 | 1993-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-30 | 1997-05-01 | 1997-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-30 | 2001-05-01 | 2001-10-31 | $7700.00 | Window Closed / Lapsed |