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US 4,912,425 AGranted
Operational amplifier circuit having stable operating point
AssigneeFujitsu Limited
InventorsOsamu Kobayashi, Kunihiko Gotoh
Life of this patent
Estimating the term…
Abstract
An operational amplifier circuit comprises a differential amplifier circuit for generating an output voltage in response to the difference in potential between two input signals, a level shift circuit for shifting the output voltage of the differential amplifier circuit, a push-pull output circuit which operates in response to the output voltages of the differential amplifier circuit and the level shift circuit, and a bias circuit for generating a bias voltage in response to a power supply voltage to control the level shift circuit. The output voltage of the level shift circuit is not affected by fluctuations of the power supply voltage.
Claims10
An operational amplifier circuit, comprising:
- first and second power supply terminal means;
- a differential amplifier circuit means, connected between said first and second power supply terminal means, for generating an output voltage in response to a difference in potential between two input signals, said output voltage varying in response to fluctuations of a power supply voltage;
- a level shift circuit means, connected to said first and second power supply terminal means, and to said differential amplifier circuit for shifting the output voltage of said differential amplifier circuit by a level shift amount dependent on said power supply voltage to generate another output voltage;
- a push-pull output circuit means, connected to said first and second power supply terminal means, to said differential amplifier circuit, and to said level shift circuit, said push-pull output circuit means being for operating in response to an output voltage of said differential amplifier circuit means and an output voltage of said level shift circuit means;
- and
- a bias circuit means, connected to said first and second power supply terminal means and to said level shift circuit, for generating a bias voltage which varies in response to fluctuations of said power supply voltage for changing said level shift amount of said level shift circuit means, to prevent the another output voltage of said level shift circuit means from being affected by any fluctuations of said power supply voltage.
3 more elements
An operational amplifier circuit, comprising:
- first and second power supply terminal means;
- a differential amplifier circuit means, connected between said first and second power supply terminal means, for generating an output voltage in response to a difference in potential between two input signals;
- a level shift circuit means, Connected to said first and second power supply terminal means, and to said differential amplifier circuit, for shifting the output voltage of said differential amplifier circuit by a predetermined value to generate another output voltage, wherein said level shift circuit means further comprises a constant current source having a conductance connected in parallel with said variable current source;
- a push-pull output circuit means, connected to said first and second power supply terminal means, to said differential amplifier circuit, and to said level shift circuit, said push-pull output circuit means being for operating in response to an output voltage of said differential amplifier circuit means and an output voltage of said level shift circuit means;
- and
- a bias circuit means, connected to said first and second power supply terminal means and to said level shift circuit, for generating a bias voltage in response to said power supply voltage for controlling said level shift circuit means to thereby prevent the another output voltage of said level shift circuit means from being affected by any fluctuations of said power supply voltage,
- wherein said level shift circuit means comprises:
- a transducer having a conductance, connected to said power supply terminal means and said differential amplifier circuit means, for reducing the output voltage thereof by said predetermined value;
- and
- a variable current source, connected between said transistor and said second power supply terminal means, and to said bias circuit means, the current of said variable current source being controlled by the bias voltage of said bias circuit.
7 more elements
Dependencies are inferred from the claim text.