US3582681A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable loss device
Assignee: International Standard Electric Corp
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Filing: 1969-10-27
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Granted: 1971-06-01
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Expires: 1989-10-27
Abstract
Abstract A transistorized AGC device is proposed for telephone subscriber sets using integrated circuit techniques. The variable loss circuit comprises two transistors bridging the transmission path. The magnitude of the impedance of the emitter-base junction is controlled by injecting a current, the magnitude of which can be varied. The control current is provided by a high impedance (constant current) source realized by two further transistors in grounded base configuration. These transistors present a high impedance to the signal currents and avoid interaction between the signal and control currents.
Inventors
- 👤 Peter Norman
- 👤 Camilo Manansala Tabalba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:18
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0082; H03G7/00; H03G7/002; H03G7/004; H03H; H03H11/00; H03H11/02; H03H11/24; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/06
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
189 words
A variable loss device for a transmission circuit carrying balanced to ground electrical signals from a source to a load, the device comprising a transmission circuit including two conductors, two transistors providing an impedance path shunted across the transmission circuit, realized by the emmiter-base circuits of the said two transistors, means connecting the emitters of the transistors to the respective conductors of the transmission circuit, means joining together the collectors of the transistors to a source of DC power, means joining the base electrodes of the transistors together and to a first reference potential, the impedance of said path being controlled by injecting into the emitter electrodes of the said two transistors equal control currents from two high impedance current sources including two further transistors having their collector electrodes connected to the respective conductors of said transmission circuit, their base electrodes joined together and to a point of second reference potential and having their emitter electrodes joined together and to one terminal of a source of control potential, the other terminal of the source of control potential being connected to the other terminal of the source of DC power.
Claim 2
Dependent Claim
189 words
A variable loss device for a transmission circuit carrying balanced to ground electrical signals from a source to a load, the device comprising a transmission circuit including two conductors, two transistors providing an impedance path shunted across the transmission circuit, realized by the emmiter-base circuits of the said two transistors, means connecting the emitters of the transistors to the respective conductors of the transmission circuit, means joining together the collectors of the transistors to a source of DC power, means joining the base electrodes of the transistors together and to a first reference potential, the impedance of said path being controlled by injecting into the emitter electrodes of the said two transistors equal control currents from two high impedance current sources including two further transistors having their collector electrodes connected to the respective conductors of said transmission circuit, their base electrodes joined together and to a point of second reference potential and having their emitter electrodes joined together and to one terminal of a source of control potential, the other terminal of the source of control potential being connected to the other terminal of the source of DC power.
Claim 3
Dependent Claim
25 words
A device as claimed in claim 1 in which the control potential is derived by tapping, amplifying and rectifying the signals transmitted by the circuit.
Claim 4
Dependent Claim
21 words
A device as claimed in claim 2 in which one terminal of the source of control potential is at earth potential.
References Cited (Backward Citations)
US3343099A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |