US3581222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear voltage controlled attenuator
Assignee: Wilton Co
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Filing: 1969-03-19
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Granted: 1971-05-25
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Expires: 1989-03-19
Abstract
Abstract A voltage controlled attenuator for use in an automatic gain control circuit. The attenuator includes a first transistor having a relatively high output impedance driven by an AC input signal. Its collector output is coupled to the coupled emitter inputs of two common base connected amplifiers which are differentially driven by a control signal to split the output current of the first transistor between them. The output voltage which is attenuated in proportion to the control signal is then taken from the collector of one of the common base amplifiers.
Inventors
- 👤 Duane E Dunwoodie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:16
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0017; H03G1/0023; H03G3/00; H03G3/20; H03G3/30; H03G3/3036
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
191 words
A voltage controlled attenuator comprising, first transistor means having base input and collector output terminals and connected in a common-emitter amplifier configuration, said input terminal receiving an AC input signal and said output terminal having an output signal current with an instantaneous magnitude proportional to the instantaneous magnitude of said AC input signal, said output terminal having a relatively high output impedance, second and third transistors, two similar terminals of said second and third transistors being coupled together and to said output collector terminal of said first transistor means, said terminals of said second and third transistors having a relatively low input impedance whereby the ratio of said high output impedance of said first transistor means and said input impedance is large so that nonlinearities in said input impedance are in effect eliminated by said relatively linear high output impedance, means for coupling a control signal to said second and third transistors for differentially controlling said output signal current through said transistors, output voltage means coupled to an output terminal of one of said second and third transistors having an output voltage with a magnitude proportional to said control signal voltage.
Claim 2
Dependent Claim
191 words
A voltage controlled attenuator comprising, first transistor means having base input and collector output terminals and connected in a common-emitter amplifier configuration, said input terminal receiving an AC input signal and said output terminal having an output signal current with an instantaneous magnitude proportional to the instantaneous magnitude of said AC input signal, said output terminal having a relatively high output impedance, second and third transistors, two similar terminals of said second and third transistors being coupled together and to said output collector terminal of said first transistor means, said terminals of said second and third transistors having a relatively low input impedance whereby the ratio of said high output impedance of said first transistor means and said input impedance is large so that nonlinearities in said input impedance are in effect eliminated by said relatively linear high output impedance, means for coupling a control signal to said second and third transistors for differentially controlling said output signal current through said transistors, output voltage means coupled to an output terminal of one of said second and third transistors having an output voltage with a magnitude proportional to said control signal voltage.
Claim 3
Dependent Claim
91 words
A voltage controlled attenuator as in claim 1 for use in an automatic gain control circuit together with feedback control means including rectifier means coupled to said output voltage means for rectifying said output voltage, comparator means for comparing said rectified output voltage with a reference signal and producing an error signal indicative of the difference between said rectified output voltage and said reference signal said error signal serving as said control signal to said second and third transistors whereby the average DC level of said AC signal is maintained constant.
Claim 4
Dependent Claim
36 words
A voltage controlled attenuator as in claim 1 in which said second and third transistors are connected as common base amplifiers with their emitter terminals coupled together and to said output terminal of said first transistor.
Claim 5
Dependent Claim
54 words
A voltage controlled attenuator as in claim 1 in which said means for coupling said control signal to said second and third transistors include means for coupling to the base input terminal of such transistors said control signal and coupling the base input terminal of said other of such transistors to a fixed bias.
Claim 6
Dependent Claim
36 words
A voltage controlled attenuator as in claim 4 in which said second and third transistors are connected as common base amplifiers with their emitter terminals coupled together and to said output terminal of said first transistor.
Claim 7
Dependent Claim
91 words
A voltage controlled attenuator as in claim 1 where said first transistor means includes an emitter terminal and together with first and second resistors series coupled between said emitter terminal and ground, and together with capacitor means coupled to the junction of said first and second resistors to provide an AC gRound for said first resistor whereby the gain of said first transistor means is proportional to the magnitude of said first resistor and the operating current of said first transistor means is established by both said first and second resistors.
Claim 8
Dependent Claim
37 words
A voltage controlled attenuator as in claim 6 in which said second and third transistors are connected as common base amplifiers with their emitter terminals coupled together and to said collector output terminal of said first transistor.
Claim 9
Dependent Claim
54 words
A voltage controlled attenuator as in claim 6 in which said means for coupling said control signal to said second and third transistors include means for coupling to the base input terminal of such transistors said control signal and coupling the base input terminal of said other of such transistors to a fixed bias.
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) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |