US4020363A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integration circuit with a positive feedback resistor
Assignee: Fujinon Corp
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Filing: 1975-12-23
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Granted: 1977-04-26
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Expires: 1995-12-23
Abstract
Abstract In an integration circuit including an operational amplifier wherein an integrating capacitor and a switch are connected in series across the operational amplifier as a negative feedback circuit, a positive feedback resistor is connected between the connecting point between the integrating capacitor and the switch and the reference input terminal of the operational amplifier. The potential difference across the integrating capacitor is made zero in order to remove the influence of the leakage current of the switch when the switch is in its OFF-state.
Inventors
- 👤 Saburo Numata
- 👤 Shinichiro Fujino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:33
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/18; G06G7/184; G06G7/186; G06G7/1865
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
148 words
An integration circuit comprising an operational amplifier, a negative feedback circuit composed of an integrating capacitor and a switch means connected in series therewith, said negative circuit being connected between the output terminal and the negative input terminal of the operational amplifier, a negative feedback element connected in parallel with said negative feedback circuit, and a current limiting means connected between the positive input terminal and the negative input terminal, wherein the improvement comprising a positive feedback resistor connected between the positive input terminal and a connecting point between said integrating capacitor and said switch means, the resistance of said feedback resistor being higher than the resistance of said switch means when the switch means is in its ON-state and lower than the resistance of said switch means when the switch means is in its OFF-state, whereby the potential difference across said integrating capacitor is made substantially zero.
Claim 2
Dependent Claim
148 words
An integration circuit comprising an operational amplifier, a negative feedback circuit composed of an integrating capacitor and a switch means connected in series therewith, said negative circuit being connected between the output terminal and the negative input terminal of the operational amplifier, a negative feedback element connected in parallel with said negative feedback circuit, and a current limiting means connected between the positive input terminal and the negative input terminal, wherein the improvement comprising a positive feedback resistor connected between the positive input terminal and a connecting point between said integrating capacitor and said switch means, the resistance of said feedback resistor being higher than the resistance of said switch means when the switch means is in its ON-state and lower than the resistance of said switch means when the switch means is in its OFF-state, whereby the potential difference across said integrating capacitor is made substantially zero.
Claim 3
Dependent Claim
17 words
An integration circuit as defined in claim 1 wherein said switch means is a semiconductor switching element.
Claim 4
Dependent Claim
16 words
An integration circuit as defined in claim 2 wherein said switch means is a MOS FET.
Claim 5
Dependent Claim
17 words
An integration circuit as defined in claim 2 wherein said switch means is a field effect transistor.
Claim 6
Dependent Claim
30 words
An integration circuit as defined in claim 1 wherein said switch means is a mechanical switch which has a little conductivity to cause leakage of current when it is closed.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |