Patent US3668542A successfully refreshed from Google Patents.
US3668542A
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Audio compression circuit
Assignee: Collins Radio Co
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Filing: 1970-02-03
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Granted: 1972-06-06
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Expires: 1990-02-03
Abstract
Abstract An audio compressor using a P-channel junction field effect transistor (JFET) as a voltage controlled resistor at the input of an integrated circuit operational amplifier. Good frequency response and fast attack are provided since the gain control element is not a part of the biasing circuit with limitations due to settling time thereby avoided.
Inventors
- 👤 C Daniel W Stoffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:28
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/25; H; H03; H03G; H03G7/00; H03G7/06
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
135 words
In an audio compression circuit with signal input coupling means, amplifying means, and output signal circuit means: a Field effect semiconductor device having at least three electrode connections, first, second, and third electrode means connected in said signal input coupling means with a first to third electrode means input signal circuit path; an (AGC) automatic gain control circuit connected from said output signal circuit means to said second electrode means; wherein said second electrode means is a gate control electrode connection for the field effect semiconductor device; and wherein said AGC circuit includes voltage rectifying means; said AGC circuit also includes filter circuit means connected from the interconnection between said voltage rectifying means and said gate control electrode connection and ground; and capacitive means and resistive means connected in parallel from said interconnection to ground.
Claim 2
Dependent Claim
135 words
In an audio compression circuit with signal input coupling means, amplifying means, and output signal circuit means: a Field effect semiconductor device having at least three electrode connections, first, second, and third electrode means connected in said signal input coupling means with a first to third electrode means input signal circuit path; an (AGC) automatic gain control circuit connected from said output signal circuit means to said second electrode means; wherein said second electrode means is a gate control electrode connection for the field effect semiconductor device; and wherein said AGC circuit includes voltage rectifying means; said AGC circuit also includes filter circuit means connected from the interconnection between said voltage rectifying means and said gate control electrode connection and ground; and capacitive means and resistive means connected in parallel from said interconnection to ground.
Claim 3
Dependent Claim
18 words
The audio compression circuit of claim 1, wherein said field effect semiconductor device is a low Pinch-Off JFET.
Claim 4
Dependent Claim
27 words
The audio compression circuit of claim 1, wherein resistive means is included in said AGC circuit between said output signal circuit means and said voltage rectifying means.
Claim 5
Dependent Claim
48 words
The audio compression circuit of claim 1, wherein said amplifying means is an operational amplifier circuit with a feedback output to input circuit connection with resistance value means Rf, and with closed-loop gain (with Rds being drain-to-source output resistance) and, Rds is a function of the AGC voltage.
References Cited (Backward Citations)
US3334308A
Cited
US3449684A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |