US3921091A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Amplifier circuit
Assignee: US Philips Corp
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Filing: 1975-01-16
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Granted: 1975-11-18
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Expires: 1995-01-16
Abstract
Abstract Amplifier circuit having a gain which is adjustable by means of a control quantity. The circuit comprises a differential transistor pair the tail current of which is supplied by an input amplifier. The collector of one of the transistors of the differential part is connected in a negative-feedback sense to an input of the input amplifier, and the control quantity is applied as a differential voltage to the bases of the transistors of the differential pair.
Inventors
- 👤 Kessel Theodorus Jozef Van
- 👤 Gerrit Jan Scholl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:29
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0017; H03G1/0023
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
114 words
A circuit comprising an amplifier having an at least a first input means for receiving an input signal to be amplified, and a voltage source output means having a low output impedance; first and second transistors each having emitter electrodes coupled to said output means, base electrodes adapted to receive a differential control signal, whereby a division of the output current from said amplifier is effective between said transistors in accordance with said control signal, and collector electrodes; means coupled to said second transistor for providing an output signal in accordance with the current therethrough; and alternating and direct current negative feedback means coupled between one amplifier input means and said first transistor collector.
Claim 2
Dependent Claim
114 words
A circuit comprising an amplifier having an at least a first input means for receiving an input signal to be amplified, and a voltage source output means having a low output impedance; first and second transistors each having emitter electrodes coupled to said output means, base electrodes adapted to receive a differential control signal, whereby a division of the output current from said amplifier is effective between said transistors in accordance with said control signal, and collector electrodes; means coupled to said second transistor for providing an output signal in accordance with the current therethrough; and alternating and direct current negative feedback means coupled between one amplifier input means and said first transistor collector.
Claim 3
Dependent Claim
26 words
A circuit as claimed in claim 1 wherein said providing means comprises an impedance element coupled between said amplifier output means and both of said emitters.
Claim 4
Dependent Claim
43 words
A circuit as claimed in claim 1 wherein said feedback means comprises a first impedance element, and further comprising a second impedance element having a first end coupled to said first transistor collector and a second end adapted to receive a constant potential.
Claim 5
Dependent Claim
53 words
A circuit as claimed in claim 3 wherein said second impedance element comprises a first resistor, a capacitor series coupled to said resistor, and a second resistor shunt coupled to said capacitor and having a first end coupled to said second transistor collector and a second end adapted to receive a constant potential.
Claim 6
Dependent Claim
44 words
A circuit as claimed in claim 1 further comprising a comparison circuit means having a first input coupled to said providing means, a second input means for receiving a reference signal, and an output means coupled to said bases for supplying said control signal.
Claim 7
Dependent Claim
24 words
A circuit as claimed in claim 5 further comprising a detector circuit means coupled between said providing means and said comparison circuit first input.
Claim 8
Dependent Claim
38 words
A circuit as claimed in claim 1 further comprising means for always forwardly biasing said first transistor comprising a peak detector means having an input coupled to said output means and an output coupled to said input means.
Claim 9
Dependent Claim
84 words
A circuit as claimed in claim 7 wherein said detector circuit means comprises a diode forwardly coupled to said output means, a capacitor coupled to said diode and adapted to be coupled to a source of constant potential, a first resistor parallel coupled to said capacitor, and third transistor having emitter, base, and collector electrodes and disposed in a common base configuration, the collector-emitter path of said third transistor being coupled between an amplifier input and the junction of said capacitor and first resistor.
Claim 10
Dependent Claim
49 words
A circuit as claimed in claim 1 further comprising an input impedance element having a first end adapted to receive said input signal and a second end coupled to said input means; and another impedance element coupled between said input impedance element first end and said second transistor collector.
Claim 11
Dependent Claim
95 words
A circuit as claimed in claim 1 wherein said input means comprises a noninverting input and said amplifier further comprises an inverting input couPled to said first transistor collector; and further comprising a first resistor having a first end coupled to said inverting input and a second end adapted to be coupled to a constant potential; a second resistor coupled between said noninverting input to said second transistor collectors, and a third resistor having a first end coupled to said second transistor collector and a second end adapted to be coupled to a constant potential.
Claim 12
Dependent Claim
71 words
A circuit as claimed in claim 1 further comprising a third transistor of the same conductivity type as said first transistor and having a collector and a base coupled together and to the first transistor emitter and an emitter coupled to the collector of said first transistor, and means coupled between said emitters of said first and second transistors for producing the second transistor emitter voltage comprising a full wave rectifier.
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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |