US3794931A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic gain control
Assignee: United States Department of the Army
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Filing: 1972-10-10
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Granted: 1974-02-26
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Expires: 1992-10-10
Abstract
Abstract An automatic gain control circuit is disclosed for varying the gain of an amplifier as a function of a separate control voltage. Feedback around the amplifier is varied independently from the amplifier output signal, changing the amplifier gain curve without changing the feedback control voltage therefor. Pulsetime modulation is used for feedback control with the pulse amplitude being proportional to the amplifier output and the pulse width a function of the control voltage. An electronic switch in the amplifier feedback path affords complete isolation between the driving voltage and the amplifier output signal. The switch is gated with a bistable multivibrator that is alternately triggered by pulses from a fixed pulse generator and pulses from a variable slope, ramp generator.
Inventors
- 👤 P Albrecht
- 👤 K Bays
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:23
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/02; H03G3/04; H03G3/10; H03G3/12; H03G1/00; H03G1/0005; H03G1/0017
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
138 words
An electronic gain control circuit for varying the feedback of an amplifier and comprising: an electronic switch having a signal input and output, said switch being connected between the output of said amplifier and the input of said amplifier for providing an amplifier feedback signal; gating means coupled to said switch for opening and closing the switch, said gating means including a flip-flop having first and second outputs for coupling two stable output states simultaneously to said switch for activating and deactivating said switch and having first and second inputs, a pulse generator connected to said first input of the flip-flop for coupling a controlled series of pulses thereto and A trigger circuit connected to said second flip-flop input for resetting said flip-flop; and timing means coupled to said gating means for controllably varying the gating period thereof.
Claim 2
Dependent Claim
138 words
An electronic gain control circuit for varying the feedback of an amplifier and comprising: an electronic switch having a signal input and output, said switch being connected between the output of said amplifier and the input of said amplifier for providing an amplifier feedback signal; gating means coupled to said switch for opening and closing the switch, said gating means including a flip-flop having first and second outputs for coupling two stable output states simultaneously to said switch for activating and deactivating said switch and having first and second inputs, a pulse generator connected to said first input of the flip-flop for coupling a controlled series of pulses thereto and A trigger circuit connected to said second flip-flop input for resetting said flip-flop; and timing means coupled to said gating means for controllably varying the gating period thereof.
Claim 3
Dependent Claim
73 words
An electronic gain control circuit as set forth in claim 1 wherein said timing means comprises: a ramp generator coupled to said trigger circuit for periodically changing the state thereof, thereby resetting said flip-flop, and a curve-shaper connected to said ramp generator for varying the time period of said ramp generator; and said flip-flop having a third output coupled as an input to said ramp generator for starting and stopping a ramp cycle.
Claim 4
Dependent Claim
75 words
An electronic gain control circuit as set forth in claim 2 wherein said ramp generator comprises: a double-emitter follower input responsive to said third flip-flop output, first and second charge storage networks connected across said double-emitter follower, and an output connected between said second charge storage network and said trigger circuit for changing the state of said trigger circuit; and said curve shaper is connected to said first charge storage network across said double-emitter follower.
Claim 5
Dependent Claim
129 words
An electronic gain control circuit as set forth in claim 3 wherein said curve shaper comprises: first and second transistors; said first transistor having the base and collector connected to biasing voltage and the emitter to a grounded resistor for maintaining continuous current therethrough, and a variable resistance connected between the base and a circuit ground return for changing the bias thereof; the base of said second transistor being coupled to the emitter of said first transistor for biasing said second transistor, a variable resistor coupling the emitter of said second transistor to ground, and a blocking diode connected between the collector of said second transistor and the first charge storage network of said ramp generator for controlling charging rate of said network when said double-emitter follower is activated.
Claim 6
Dependent Claim
55 words
An electronic gain control circuit as set forth in claim 2 and further comprising a control voltage coupled as an input to said trigger circuit for controlling the voltage level at which the trigger circuit activates, and a reference voltage source coupled to said trigger circuit for regulating the maximum level of control voltage activation.
Claim 7
Dependent Claim
123 words
An electronic gain control circuit as set forth in claim 5 wherein said trigger circuit comprises: first, second and third transistors; said first transistor having the base thereof coupled to receive the output of said ramp generator, a capacitor coupling the collector of said first transistor to the base of said third transistor for switching the state thereof; an output capacitor coupled between the collector of said third transistor for coupling a reset signal to said flip-flop; the base of said second transistor being directly coupled to said reference voltage source and resistively coupled to said control voltage; a resistance coupled between the emitter of said second transistor and ground; and a diode coupled between the emitters of said first and second transistors.
Claim 8
Dependent Claim
78 words
An electronic gain control circuit as set forth in claim 6 wherein said ramp generator comprises: a double-emitter follower input network responsive to said third output of said flip-flop, first and second charge storage networks connected across said double-emitter follower, and an output connected between said second charge storage network and said trigger circuit for changing the state of said trigger circuit; and said curve shaper is connected to said first charge storage network across said double-emitter follower.
Claim 9
Dependent Claim
102 words
An electronic gain control circuit as set forth in claim 7 wherein said flip-flop is a bistable multivibrator, and said electronic switch comprises: a direct-coupled, field-effect transistor switch connected between said amplifier output and input for providing controlled amplifier feedback, a parallel diode-capacitor network connected between a gate of saiD direct-coupled switch and a first of said flip-flop stable outputs for activating said switch; and a field-effect transistor switch shunt connected between the output of said direct-coupled switch and ground for terminating amplifier feedback signals, said shunt having a gate coupled to the second of said flip-flop outputs for deactivating said switch.
Claim 10
Dependent Claim
148 words
An electronic gain control circuit as set forth in claim 8 wherein said curve shaper comprises: first and second transistors; said first transistor having the base and collector thereof connected to biasing voltage and the emitter to a grounded resistor for maintaining continuous current therethrough, and a variable resistance connected between the base and ground for changing the transistor bias; said second transistor having the base connected to the emitter of said first transistor for biasing said second transistor, a variable resistor connected between the emitter of said second transistor and ground, and a diode connected between the collector of said second transistor and the first charge storage network of said ramp generator for controlling charging rate of said network when said double-emitter follower is activated; and said gain control circuit further comprising a shaping network connected between the output of said direct-coupled switch and said amplifier input.
References Cited (Backward Citations)
US3582675A
Cited
US3711783A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-25 | 1977-08-27 | 1978-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-25 | 1981-08-27 | 1982-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-25 | 1985-08-27 | 1986-02-26 | $7700.00 | Window Closed / Lapsed |