Patent WO1992011815A2 successfully refreshed from Google Patents.
US3761741A
Expired / Lapsed
US
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Electrically variable impedance utilizing the base emitter junctions of transistors
Assignee: Signetics Corp
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Filing: 1972-06-21
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Granted: 1973-09-25
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Expires: 1992-06-21
Abstract
Abstract A variable impedance utilizing the diode characteristic of the base-emitter junction of a transistor. The voltage across the base-emitter stays constant so that a control voltage used to change the d.c. emitter current changes the impedance of the junction. When such a diode connected transistor shunts a signal line it attenuates the signal on the signal line. In order to reduce non-linearities in impedance caused by application of the signal, a diode connected transistor has another transistor connected thereto in a differential circuit so that an increase in the emitter current (decrease in impedance) of one due to application of the signal causes a corresponding decrease in emitter current (and increase in impedance) of the other so that the non-linearities cancel out. In another embodiment the two transistors are placed in the feedback loop of a differential amplifier with the impedance of the two transistors serving as the load for the differential amplifier, which further reduces nonlinearities. Several such transistor circuits may be connected in series to provide more junctions and hence a wider range of variable impedance.
Inventors
- 👤 W Hoeft
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:45
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0082; H03H; H03H11/00; H03H11/02; H03H11/24
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
117 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series with each other and to said output terminal, means for establishing emitter currents in said first and second transistors whereby their impedances are established, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters commonly connected whereby an increase in emitter current of one of said first and second transistors due to the signal source causes an approximately equal decrease in emitter current of the other of said first and second transistors.
Claim 2
Dependent Claim
117 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series with each other and to said output terminal, means for establishing emitter currents in said first and second transistors whereby their impedances are established, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters commonly connected whereby an increase in emitter current of one of said first and second transistors due to the signal source causes an approximately equal decrease in emitter current of the other of said first and second transistors.
Claim 3
Dependent Claim
37 words
An electrically variable shunt impedance in accordance with claim 1 wherein said means for establishing emitter currents in said first and second transistors includes a current source connected to the emitters of said first and second transistors.
Claim 4
Dependent Claim
151 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series with each other and to said output terminal and shunting the signal line, means for establishing emitter currents in said first and second transistors whereby their impedances are established, an amplifier having a feedback loop, said first and second transistors being in the feedback loop of said amplifier and constituting the load for the amplifier, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters coupled together whereby an increase in emitter current of one of said first and second transistors due to the signal source is coupled through the amplifier to the other of the transistors to cause a decrease in the emitter current thereof.
Claim 5
Dependent Claim
151 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series with each other and to said output terminal and shunting the signal line, means for establishing emitter currents in said first and second transistors whereby their impedances are established, an amplifier having a feedback loop, said first and second transistors being in the feedback loop of said amplifier and constituting the load for the amplifier, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters coupled together whereby an increase in emitter current of one of said first and second transistors due to the signal source is coupled through the amplifier to the other of the transistors to cause a decrease in the emitter current thereof.
Claim 6
Dependent Claim
37 words
An electrically variable shunt impedance in accordance with claim 3 wherein said means for establishing emitter currents in said first and second transistors comprises a current source connected to the emitters of said first and second transistors.
Claim 7
Dependent Claim
40 words
An electrically variable shunt impedance in accordance with claim 3 wherein said first and second transistors are of one conductivity type and wherein said amplifier comprises a self-biasing differential amplifier forMed of third and fourth transistors of opposite conductivity type.
Claim 8
Dependent Claim
46 words
An electrically variable shunt impedance in accordance with claim 5 wherein the collector of said first transistor is connected to the base and collector of said third transistor and the base and collector of said second transistor is connected to the collector of said fourth transistor.
Claim 9
Dependent Claim
85 words
An electrically variable shunt impedance in accordance with claim 5 wherein the base and collector of said second transistor are connected to the collector of said fourth transistor and the collector of said first transistor is connected to the collector of said third transistor, and including a fifth transistor having its base connected to the collector of said first transistor and its emitter connected to the base of said third transistor, said fifth transistor functioning to provide base currents for said third and fourth transistors.
Claim 10
Dependent Claim
40 words
An electrically variable impedance in accordance with claim 5 wherein said current source is varied in accordance with a predetermined function in order to vary the shunt impedance and hence attenuation of a signal in accordance with that predetermined function.
Claim 11
Dependent Claim
64 words
An electrically variable impedance in accordance with claim 5 including a plurality of additional transistors of said one conductivity type connected with their base emitter junctions in series with said first and second transistors with one-half of said additional transistors being poled in the direction of said first transistor and one-half of said additional transistors being poled in the direction of said second transistor.
Claim 12
Dependent Claim
34 words
An electrically variable impedance in accordance with claim 9 including a plurality of transistors of said one conductivity type connected with their base emitter junctions in series with the emitter of said fourth transistor.
Claim 13
Dependent Claim
155 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance connected to said output terminal and comprising a plurality of series connected impedance stages, each impedance stage comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series, means for establishing emitter currents in said first and second transistors whereby their impedances are established, an amplifier having a feedback loop, said first and second transistors being in the feedback loop of said amplifier and constituting the load for the amplifier, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters coupled together whereby an increase in emitter current of one of said first and second transistors due to the signal source is coupled through the amplifier to the other of the transistors to cause a decrease in the emitter current thereof.
Claim 14
Dependent Claim
155 words
In a circuit including a signal line having a signal source and an output terminal, an electrically variable shunt impedance connected to said output terminal and comprising a plurality of series connected impedance stages, each impedance stage comprising first and second transistors each having base-emitter junctions, said base-emitter junctions connected in series, means for establishing emitter currents in said first and second transistors whereby their impedances are established, an amplifier having a feedback loop, said first and second transistors being in the feedback loop of said amplifier and constituting the load for the amplifier, said base-emitter junctions of said first and second transistors being oppositely poled with respect to each other with their emitters coupled together whereby an increase in emitter current of one of said first and second transistors due to the signal source is coupled through the amplifier to the other of the transistors to cause a decrease in the emitter current thereof.
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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) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |