Patent US3720549A successfully refreshed from Google Patents.
US3663900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Voltage controlled attenuator
Assignee: Nortel Networks Ltd
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Filing: 1971-02-16
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Granted: 1972-05-16
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Expires: 1991-02-16
Abstract
Abstract The circuit controls two direct currents in two PIN diodes of an attenuator so that the product of the two currents is constant. In the circuit, an emitter-follower controls the direct current in one PIN diode in proportion to a control voltage. The direct current in the other PIN diode is controlled as dictated by the response curve of a transistor, the emitter of which is in series with a diode, in approximate proportion to the reciprocal of the voltage being developed across the one PIN diode. A bridged-T attenuator is thus controllable from a single control voltage source so that it exhibits a constant image impedance over a wide range of insertion loss.
Inventors
- 👤 Olav Peterson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:34
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/24; H03H7/25; H03H7/253; H03H7/255
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
190 words
A control circuit for controlling direct currents through a pair of diode loads such that the product of the two currents is substantially constant, the control circuit comprising: first and second resistors in series between a first voltage source and a common terminal, one end of one diode load being coNnected to the junction between the two resistors, a first transistor having a base connected to a source of control voltage and a collector connected to the other end of said one diode load, an emitter-resistor connected between a second voltage source and the emitter of the first transistor so that the first transistor is in series aiding with said one diode load, a second transistor, having a base connected to the junction between the collector of the first transistor and the other end of said one diode load, the other diode load being connected between the common terminal and the collector of the second transistor, a first diode connected between the emitter of the second transistor and the first voltage source so that the second transistor and the first diode are in series aiding with the other diode load.
Claim 2
Dependent Claim
190 words
A control circuit for controlling direct currents through a pair of diode loads such that the product of the two currents is substantially constant, the control circuit comprising: first and second resistors in series between a first voltage source and a common terminal, one end of one diode load being coNnected to the junction between the two resistors, a first transistor having a base connected to a source of control voltage and a collector connected to the other end of said one diode load, an emitter-resistor connected between a second voltage source and the emitter of the first transistor so that the first transistor is in series aiding with said one diode load, a second transistor, having a base connected to the junction between the collector of the first transistor and the other end of said one diode load, the other diode load being connected between the common terminal and the collector of the second transistor, a first diode connected between the emitter of the second transistor and the first voltage source so that the second transistor and the first diode are in series aiding with the other diode load.
Claim 3
Dependent Claim
78 words
The control circuit as defined in claim 1, further comprising: third and fourth resistors in series between the first voltage source and the common terminal, a second diode connected from the emitter of the second transistor to the junction of the third and fourth resistors so that the other diode load, the second transistor and the second diode are in series aiding, a fifth resistor connected between the first voltage source and the collector of the second transistor.
Claim 4
Dependent Claim
90 words
A control circuit as defined in claim 2 further comprising: a plurality of diodes inserted in series aiding between the first voltage source and the first resistor, a sixth resistor and a third diode connected in series between the second voltage source and the base of the first transistor, the third diode being so connected that it is in parallel aiding with the base emitter junction of the first transistor and the sixth resistor being about twice the value of the output impedance of the source of the control voltage.
Claim 5
Dependent Claim
30 words
The control circuit as defined in claim 1 for controlling the insertion loss of a bridged-T diode attenuator in which the diode loads are the diode elements of the attenuator.
Claim 6
Dependent Claim
30 words
The control circuit as defined in claim 2 for controlling the insertion loss of a bridged-T diode attenuator in which the diode loads are the diode elements of the attenuator.
Claim 7
Dependent Claim
30 words
The control circuit as defined in claim 3 for controlling the insertion loss of a bridged-T diode attenuator in which the diode loads are the diode elements of the attenuator.
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |