US3896383A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A.c. coupling network
Assignee: Allegro Microsystems LLC
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Filing: 1973-06-19
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Granted: 1975-07-22
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Expires: 1993-06-19
Abstract
Abstract An FM receiver sound channel network is presented wherein a single capacitor serves the dual roles of, filtering out amplifier bias circuit ripple, and providing a.c. interstage coupling between the detector and the audio amplifier. This circuit is especially suitable where most of the components of the sound channel take the form of an integrated circuit.
Inventors
- 👤 Alberto Bilotti
- 👤 Ronald W Lutz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:29
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/30; H03F3/3083; H03F3/3086; H03F3/3096
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
207 words
A method for coupling an electrical signal from a signal source to the input of an amplifier comprising: a. providing a signal source having a low output impedance; b. providing an amplifier circuit with a high input impedance; c. connecting a d.c. power supply containing an a.c. ripple to said amplifier for providing power thereto; d. connecting a coupling capacitor between said output of said signal source and said input of said amplifier; and e. connecting a high impedance d.c. bias circuit directly to and powered by said d.c. power supply for the purpose of providing a bias at said input of said amplifier, said bias circuit, said amplifier and said signal source having a common reference ground connection, said coupling capacitor having a low impedance at the lowest signal frequency to be amplified and having a low impedance at the frequency of ripple in said bias circuit, wherein each said high impedance is at least ten times greater than any of said low impedances, such that any ripple currents present in said bias circuit are substantially shorted to ground through said coupling capacitor and said output impedance of said signal source, and such that essentially only the amplified signal appears at the output of said amplifier.
Claim 2
Independent Claim
207 words
A method for coupling an electrical signal from a signal source to the input of an amplifier comprising: a. providing a signal source having a low output impedance; b. providing an amplifier circuit with a high input impedance; c. connecting a d.c. power supply containing an a.c. ripple to said amplifier for providing power thereto; d. connecting a coupling capacitor between said output of said signal source and said input of said amplifier; and e. connecting a high impedance d.c. bias circuit directly to and powered by said d.c. power supply for the purpose of providing a bias at said input of said amplifier, said bias circuit, said amplifier and said signal source having a common reference ground connection, said coupling capacitor having a low impedance at the lowest signal frequency to be amplified and having a low impedance at the frequency of ripple in said bias circuit, wherein each said high impedance is at least ten times greater than any of said low impedances, such that any ripple currents present in said bias circuit are substantially shorted to ground through said coupling capacitor and said output impedance of said signal source, and such that essentially only the amplified signal appears at the output of said amplifier.
Claim 3
Dependent Claim
40 words
The method of claim 1 additionally comprising forming at least a portion of the components making up said signal source, said amplifier and said bias circuit in the body of a silicon crystal by a normal integrated circuit fabrication process.
Claim 4
Dependent Claim
41 words
The method of claim 2 additionally comprising forming said coupling capacitor as a discrete circuit element and wherein said connecting of said coupling capacitor between said signal source and said amplifier is accomplished by attaching said capacitor to said integrated circuit.
Claim 5
Dependent Claim
96 words
The method of claim 2 wherein said signal source is comprised of an FM limiter circuit, an FM detector circuit and a preamplifier circuit; additionally comprising applying an FM signal to the input of said detector, obtaining a demodulated audio frequency signal from the output of said detector and connecting said audio frequency signal to the input of said preamplifier, the output signal from said preamplifier representing said signal from said signal source suCh that said integrated circuit with said coupling capacitor is suitable for use as a sound channel in an FM or television receiver.
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) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |