US3725804A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Capacitance compensation circuit for differential amplifier
Assignee: Avco Corp
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Filing: 1971-11-26
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Granted: 1973-04-03
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Expires: 1991-11-26
Abstract
Abstract A differential amplifier is often used as a signal conditioner for low level transducer pick-ups. In many such applications the differential amplifier is remotely located with respect to the transducer. If there is amplifier input capacitance, or capacitance from either transmission line to any potential other than that of a driven guard, differential error signals may be derived from common mode potentials. There is here disclosed circuit means for compensating for amplifier input capacitance and/or transmission line capacitance to unguarded potentials by use of regenerative feedback of the amplified common mode signal to each input of the differential amplifier.
Inventors
- 👤 M Langan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:56
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45479; H03F3/45928; H03F3/4595; H03F3/45955; H03F3/45959; H03F1/00; H03F1/56; H03F2200/00; H03F2200/261; H03F2203/00; H03F2203/45; H03F2203/45418; H03F2203/45544
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
179 words
In combination: a differential amplifier which comprises at least a pair of input lines and an output and which normally suffers from performance impairment due to leakage capacitances between the input lines and a point of fixed potential, means for deriving a common mode signal from said lines, and amplifying means having a gain and including a pair of adjustable capacitors individually connected to said input linEs for regeneratively capacitively feeding amplified forms of said common mode signal back to said input lines so as to compensate for the undesired effect of said leakage capacitances, the gain and the capacitors being so proportioned that: Ein X Cinput (EF - Ein) C Feedback where Ein is the input potential on an input line, Cinput is the leakage capacitance of that input line, EF is the feedback signal applied to said input line, and C Feedback is the capacitance of the associated feedback capacitor, compensation for the loading effect of the capacitors on the normal mode signal being increased as these values are decreased and as the feedback voltage is increased.
Claim 2
Dependent Claim
179 words
In combination: a differential amplifier which comprises at least a pair of input lines and an output and which normally suffers from performance impairment due to leakage capacitances between the input lines and a point of fixed potential, means for deriving a common mode signal from said lines, and amplifying means having a gain and including a pair of adjustable capacitors individually connected to said input linEs for regeneratively capacitively feeding amplified forms of said common mode signal back to said input lines so as to compensate for the undesired effect of said leakage capacitances, the gain and the capacitors being so proportioned that: Ein X Cinput (EF - Ein) C Feedback where Ein is the input potential on an input line, Cinput is the leakage capacitance of that input line, EF is the feedback signal applied to said input line, and C Feedback is the capacitance of the associated feedback capacitor, compensation for the loading effect of the capacitors on the normal mode signal being increased as these values are decreased and as the feedback voltage is increased.
References Cited (Backward Citations)
US3316495A
Cited
US3531733A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |