US4435684A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video amplifier mute circuit
Assignee: National Semiconductor Corp
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Filing: 1982-04-09
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Granted: 1984-03-06
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Expires: 2002-04-09
Abstract
Abstract A wide bandwidth amplifier is shown along with a muting circuit. The output shift between normal operation and mute is kept very small. The amplifier is useful in video disk and audio signal reproduction.
Inventors
- 👤 Ronald W. Page
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:11
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03F; H03F3/00; H03F3/181; H03F3/183; H03F3/45; H03F3/45071
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
123 words
A wide bandwidth amplifier circuit which includes a high gain amplifier capable of being muted in response to a muting signal without changing its d-c output level, said circuit comprising: a differential amplifier having a source of tail current, an inverting input terminal, a noninverting input terminal, and an output; means for returning said noninverting input to a source of constant bias potential; means for coupling said inverting input to a source of signal to be amplified; means for shunting said tail current around said differential amplifier in response to said muting signal; and means for clamping said output to a d-c level, equal to the normal output level of said differential amplifier in its active state, in response to said muting signal.
Claim 2
Dependent Claim
123 words
A wide bandwidth amplifier circuit which includes a high gain amplifier capable of being muted in response to a muting signal without changing its d-c output level, said circuit comprising: a differential amplifier having a source of tail current, an inverting input terminal, a noninverting input terminal, and an output; means for returning said noninverting input to a source of constant bias potential; means for coupling said inverting input to a source of signal to be amplified; means for shunting said tail current around said differential amplifier in response to said muting signal; and means for clamping said output to a d-c level, equal to the normal output level of said differential amplifier in its active state, in response to said muting signal.
Claim 3
Dependent Claim
30 words
The amplifier circuit of claim 1 wherein said source of constant bias includes a Zener diode biased into reverse breakdown and said means for clamping includes a matched Zener diode.
Claim 4
Dependent Claim
52 words
The amplifier circuit of claim 2 wherein said differential amplifier includes a cascaded emitter follower directly coupled to its output to provide a low impedance, signal output source and a low pass filter coupled between said emitter follower output and said inverting input whereby the operating bias of said circuit is stabilized.
Claim 5
Dependent Claim
50 words
The amplifier circuit of claim 2 wherein said means for clamping further includes a transistor that is turned on in response to said muting signal and is biased to develop a voltage drop when turned on that is equal to the base to emitter voltage drop of a conducting transistor.
References Cited (Backward Citations)
US4366442A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-06 | 1987-09-05 | 1988-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-06 | 1991-09-05 | 1992-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-06 | 1995-09-05 | 1996-03-06 | $7700.00 | Window Closed / Lapsed |