US4220987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Converter drive circuit
Assignee: AT&T Inc
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Filing: 1978-12-29
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Granted: 1980-09-02
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Expires: 1998-12-29
Abstract
Abstract A power converter circuit is disclosed utilizing pulse width modulation for power regulation. A rapid acting surge protection circuit for the power driving switch is operated from a string of zener diodes to disable the power switch. A base charge removal circuit is included for dissipating accumulated base charges on the driving transistor without the need for a bipolar driving signal for the power transistor.
Inventors
- 👤 Tadikonda N. Rao
- 👤 Thomas G. Wilson, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:37
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
63 words
A transistor base charge removal circuit for high power switching transistors characterized by charge storage means connected in shunt with the base-emitter path of said transistor for accumulating a charge during the time said switching transistor is enabled, and a base charge removal path for said switching transistor enabled by the charge on said charge storage means when said switching transistor is disabled.
Claim 2
Dependent Claim
63 words
A transistor base charge removal circuit for high power switching transistors characterized by charge storage means connected in shunt with the base-emitter path of said transistor for accumulating a charge during the time said switching transistor is enabled, and a base charge removal path for said switching transistor enabled by the charge on said charge storage means when said switching transistor is disabled.
Claim 3
Dependent Claim
24 words
The transistor base charge removal circuit according to claim 1 characterized by a diode connected in the charging circuit for said charge storage means.
Claim 4
Dependent Claim
23 words
The transistor base charge removal circuit according to claim 1 characterized in that said discharge path includes the collector-emitter path of another transistor.
Claim 5
Dependent Claim
20 words
The transistor base charge removal circuit according to claim 1 characterized in that said charge storage means comprises a capacitor.
Claim 6
Dependent Claim
66 words
A drive circuit for power switching transistors operated from a unipolar drive pulse source characterized by a capacitive charging circuit connected in parallel with said unipolar drive pulse source, means for charging said charging circuit during the active half-cycle of said drive pulse, and means for utilizing said charging circuit to remove stored base charges on said switching transistors at the end of said active half-cycle.
Claim 7
Dependent Claim
66 words
A drive circuit for power switching transistors operated from a unipolar drive pulse source characterized by a capacitive charging circuit connected in parallel with said unipolar drive pulse source, means for charging said charging circuit during the active half-cycle of said drive pulse, and means for utilizing said charging circuit to remove stored base charges on said switching transistors at the end of said active half-cycle.
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) | 1983-09-02 | 1984-03-03 | 1984-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-02 | 1988-03-03 | 1988-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-02 | 1992-03-03 | 1992-09-02 | $7700.00 | Window Closed / Lapsed |