Patent US4646029A successfully refreshed from Google Patents.
US4646029A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable-gain amplifying circuit
Assignee: Hitachi Ltd
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Filing: 1985-07-02
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Granted: 1987-02-24
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Expires: 2005-07-02
Abstract
Abstract Herein disclosed is a variable gain amplifying circuit which comprises a heating element, a heat-sensitive resistance coupled thermally to the heating element, an amplifier including the heat-sensitive resistance, and means for controlling the heat of the heat element. This heat of the heating element is controlled so as to control the value of the heat-sensitive resistance. As a result that the value of the heat-sensitive resistance is controlled, the gain of that amplifier is controlled.
Inventors
- 👤 Yasuji Kamata
- 👤 Kazuo Kato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:33
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3005; H03G3/301
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
137 words
A variable-gain amplifying circuit comprising: a heating resistor; first and second heat-sensitive resistances coupled thermally to said heating resistor; an amplifier including: a transistor having an emitter, a collector and a base, said emitter being connected through a resistance with said first heat-sensitive resistance and said collector connected with a power supply; an input terminal for feeding an input signal to the base of said transistor; and an output terminal for extracting an output signal from a connecting point of said resistance and said first heat-sensitive resistance; and an amplifier having an input terminal and an output terminal, said input terminal being fed with a voltage drop which is established in said second heat-sensitive resistance, wherein an output signal which is delivered out of said output terminal is supplied as a heating current to said heating resistor.
Claim 2
Dependent Claim
137 words
A variable-gain amplifying circuit comprising: a heating resistor; first and second heat-sensitive resistances coupled thermally to said heating resistor; an amplifier including: a transistor having an emitter, a collector and a base, said emitter being connected through a resistance with said first heat-sensitive resistance and said collector connected with a power supply; an input terminal for feeding an input signal to the base of said transistor; and an output terminal for extracting an output signal from a connecting point of said resistance and said first heat-sensitive resistance; and an amplifier having an input terminal and an output terminal, said input terminal being fed with a voltage drop which is established in said second heat-sensitive resistance, wherein an output signal which is delivered out of said output terminal is supplied as a heating current to said heating resistor.
Claim 3
Dependent Claim
34 words
A variable-gain amplifying circuit according to claim 1, wherein said heating resistor and said first and second heat-sensitive resistances are arranged on a common substrate made of a substance having a high thermal conductivity.
Claim 4
Dependent Claim
216 words
A variable-gain amplifying circuit comprising: a heating resistor; first and second heat-sensitive resistances respectively coupled thermally to said heating resistor and having positive and negative temperature coefficients, respectively; third and fourth heat-sensitive resistances respectively coupled thermally to said heating resistor and having the same characteristics as those of said first and second heat-sensitive resistances, respectively; an amplifier including: a transistor having an emitter, a collector and a base, said emitter being connected with the series circuit of said first and second heat-sensitive resistances and said collector being connected with a power supply; an input terminal for feeding an input signal to said base of said transistor; and an output terminal for extracting an output signal from a connecting point of said first and second heat-sensitive resistances; and a differential amplifier having two input terminals and an output terminal, one of said input terminals being connected with a connecting point of said third and fourth heat-sensitive resistances, which are connected in series between said power supply and a reference potential, and the other of said input terminals connected with a moving terminal of a variable resistance, which is connected between said power supply and said reference potential, and wherein said output terminal is connected with said heating resistor for feeding its output signal as a heating current.
Claim 5
Dependent Claim
216 words
A variable-gain amplifying circuit comprising: a heating resistor; first and second heat-sensitive resistances respectively coupled thermally to said heating resistor and having positive and negative temperature coefficients, respectively; third and fourth heat-sensitive resistances respectively coupled thermally to said heating resistor and having the same characteristics as those of said first and second heat-sensitive resistances, respectively; an amplifier including: a transistor having an emitter, a collector and a base, said emitter being connected with the series circuit of said first and second heat-sensitive resistances and said collector being connected with a power supply; an input terminal for feeding an input signal to said base of said transistor; and an output terminal for extracting an output signal from a connecting point of said first and second heat-sensitive resistances; and a differential amplifier having two input terminals and an output terminal, one of said input terminals being connected with a connecting point of said third and fourth heat-sensitive resistances, which are connected in series between said power supply and a reference potential, and the other of said input terminals connected with a moving terminal of a variable resistance, which is connected between said power supply and said reference potential, and wherein said output terminal is connected with said heating resistor for feeding its output signal as a heating current.
Claim 6
Dependent Claim
36 words
A variable-gain amplifying circuit according to claim 3, wherein said heating resistor and said first, second, third and fourth heat-sensitive resistances are arranged on a common substrate made of a substance having a high thermal conductivity.
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) | 1990-02-23 | 1990-08-25 | 1991-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-23 | 1994-08-25 | 1995-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-23 | 1998-08-25 | 1999-02-24 | $7700.00 | Window Closed / Lapsed |