Patent US3780321A successfully refreshed from Google Patents.
US3780321A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear discharge circuit
Assignee: AT&T Inc
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Filing: 1972-10-02
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Granted: 1973-12-18
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Expires: 1992-10-02
Abstract
Abstract A capacitor is linearly discharged through a series circuit formed by the drain-source path of a field effect transistor and a resistor. Linear discharge is provided by maintaining a fixed voltage across the resistor, and this is accomplished by connecting the gate-source junction of the field effect transistor in parallel with the resistor; the gate-to-source voltage will be constant provided only that the source current is constant and this is assured by means of a constant current generator connected to the field effect transistor source lead.
Inventors
- 👤 N Lentz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:13
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/50
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
103 words
A circuit comprising, a capacitor; a resistor; a field effect transistor; said capacitor and resistor beIng connected in series with the drain-source path of the field effect transistor; said resistor being connected in parallel with the gate-source junction of the field effect transistor; and means connected to the drain-source path for providing a constant source current to the field effect transistor; said means for providing a constant source current including an emitter-follower transistor bootstrapped by a resistive connection between the emitter and the base of the emitter-follower, the base of the emitterfollower transistor being connected to the source of the field effect transistor.
Claim 2
Dependent Claim
103 words
A circuit comprising, a capacitor; a resistor; a field effect transistor; said capacitor and resistor beIng connected in series with the drain-source path of the field effect transistor; said resistor being connected in parallel with the gate-source junction of the field effect transistor; and means connected to the drain-source path for providing a constant source current to the field effect transistor; said means for providing a constant source current including an emitter-follower transistor bootstrapped by a resistive connection between the emitter and the base of the emitter-follower, the base of the emitterfollower transistor being connected to the source of the field effect transistor.
Claim 3
Dependent Claim
28 words
A circuit as claimed in claim 1 wherein said circuit is supplied with a drain-to-source voltage such that the field effect transistor operates in a constant current region.
Claim 4
Dependent Claim
36 words
A circuit as claimed in claim 1 wherein an output terminal is connected to the emitter of the emitter-follower, the emitter-follower providing at the output a low impedance voltage proportional to the voltage of the capacitor.
Claim 5
Dependent Claim
115 words
A circuit comprising, a capacitor; a field effect transistor; a series combination of the drain-source path of the field effect transistor and a discharge resistor connected to form a discharge path for the capacitor; means connecting the gate-source path of the field effect transistor across the discharge resistor; and a constant current generator connected to the source of the field effect transistor for maintaining a constant source current; the constant current generator including an emitter-follower transistor having its base connected to the source of the field effect transistor, a bootstrap resistor connected across the base-emitter junction of the emitter-follower transistor, and bias means for operating the emitter-follower so that its base-emitter voltage is essentially fixed.
Claim 6
Dependent Claim
115 words
A circuit comprising, a capacitor; a field effect transistor; a series combination of the drain-source path of the field effect transistor and a discharge resistor connected to form a discharge path for the capacitor; means connecting the gate-source path of the field effect transistor across the discharge resistor; and a constant current generator connected to the source of the field effect transistor for maintaining a constant source current; the constant current generator including an emitter-follower transistor having its base connected to the source of the field effect transistor, a bootstrap resistor connected across the base-emitter junction of the emitter-follower transistor, and bias means for operating the emitter-follower so that its base-emitter voltage is essentially fixed.
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) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |