US3864623A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pseudo balanced constant current supply
Assignee: Fujitsu IT Holdings Inc
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Filing: 1973-10-05
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Granted: 1975-02-04
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Expires: 1993-10-05
Abstract
Abstract An electronic circuit designed particularly for data communications systems for providing equal and opposite current to a pair of line conductors. The circuit employs an operational amplifier with a sampling resistance connected in series with a current supply. The sampling resistance provides the input signal to the operational amplifier. Dual feedback is provided with one feedback path including a resistance matching the sampling resistance.
Inventors
- 👤 David W Luce
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:09
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/461
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
209 words
Current supply circuit for a pair of line conductors comprising: a voltage supply; said voltage supply comprising a negative polarity constant current source and a positive polarity constant current source and switch means for selectively applying one or both of said constant current sources to a common output terminal of said voltage supply; a pair of line conductors; a first resistance connected in series between the said output terminal of said supply and the first of said pair of line conductors; an amplifier having a gain of substantially minus one and a pair of input terminals; means connecting the input terminals of said amplifier to the opposite ends of said first resistance whereby the input voltage to said amplifier is a voltage drop proportional to the current in the first of said pair of line conductors; a first feedback path from the output of said amplifier to one of said pair of input terminals; a second resistance equal in value to said first resistance and connected in series with the output of said amplifier and the second of said line conductors; and a second feedback path between the end of said second resistance remote from said amplifier to the second of said pair of input terminals of said amplifier.
Claim 2
Dependent Claim
209 words
Current supply circuit for a pair of line conductors comprising: a voltage supply; said voltage supply comprising a negative polarity constant current source and a positive polarity constant current source and switch means for selectively applying one or both of said constant current sources to a common output terminal of said voltage supply; a pair of line conductors; a first resistance connected in series between the said output terminal of said supply and the first of said pair of line conductors; an amplifier having a gain of substantially minus one and a pair of input terminals; means connecting the input terminals of said amplifier to the opposite ends of said first resistance whereby the input voltage to said amplifier is a voltage drop proportional to the current in the first of said pair of line conductors; a first feedback path from the output of said amplifier to one of said pair of input terminals; a second resistance equal in value to said first resistance and connected in series with the output of said amplifier and the second of said line conductors; and a second feedback path between the end of said second resistance remote from said amplifier to the second of said pair of input terminals of said amplifier.
Claim 3
Dependent Claim
18 words
The combination in accordance with claim 1 wherein said first and second feedback paths include equal value resistances.
Claim 4
Dependent Claim
51 words
The combination in accordance with claim 1 wherein a pair of equal resistances are connected in series between respective ends of said first resistance and the input terminals of said amplifier and said pair of equal resistances have values in the order of several times the resistance of said first resistance.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |