Amplifier
First Claim
Patent Images
1. An amplifier comprising:
- a first voltage follower circuit that includes a plurality of P-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage, applied to a positive-phase input terminal of the first voltage follower circuit, and an input signal voltage, applied to a negative-phase input terminal of the first voltage follower circuit, supplied directly with feedback from an output terminal via a first resistor, by resistance of the first resistor;
a first current mirror circuit that receives the current output by the first voltage follower circuit;
a second voltage follower circuit that includes a plurality of N-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage applied to a positive-phase input terminal of the second voltage follower circuit, and the input signal voltage, applied to a negative-phase input terminal of the second voltage follower circuit, supplied directly with feedback from an output terminal, via a second resistor, by resistance of the second resistor; and
a second current mirror circuit that receives the current output by the second voltage follower circuit.
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Abstract
An amplifier includes a first voltage follower including P-type MOS transistors and a second voltage follower including N-type MOS transistors. The first voltage follower amplifies without being saturated even if an input signal voltage approaches a level of a power supply voltage when the input signal voltage is at least equal to a bias voltage, but does not amplify when the input voltage is less than the bias voltage. A second voltage follower of the amplifier amplifies without being saturated even if an input signal voltage approaches a ground potential when the input signal voltage is less than the bias voltage, but does not amplify when the input voltage is at least equal to the bias voltage.
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Citations
7 Claims
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1. An amplifier comprising:
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a first voltage follower circuit that includes a plurality of P-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage, applied to a positive-phase input terminal of the first voltage follower circuit, and an input signal voltage, applied to a negative-phase input terminal of the first voltage follower circuit, supplied directly with feedback from an output terminal via a first resistor, by resistance of the first resistor;
a first current mirror circuit that receives the current output by the first voltage follower circuit;
a second voltage follower circuit that includes a plurality of N-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage applied to a positive-phase input terminal of the second voltage follower circuit, and the input signal voltage, applied to a negative-phase input terminal of the second voltage follower circuit, supplied directly with feedback from an output terminal, via a second resistor, by resistance of the second resistor; and
a second current mirror circuit that receives the current output by the second voltage follower circuit. - View Dependent Claims (2, 3)
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4. An amplifier comprising:
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a voltage follower circuit that includes P-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage, applied to a positive-phase input terminal, and an input signal voltage applied to a negative-phase input terminal, supplied directly with a feedback from an output terminal, via a resistor, by resistance of the resistor;
a current mirror circuit that receives the current output by the voltage follower circuit; and
a series circuit connected between ground and an output line of the current mirror circuit, wherein the series circuit includes a load resistor and an output bias voltage source. - View Dependent Claims (5)
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6. An amplifier comprising:
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a voltage follower circuit that includes N-type MOS transistors and outputs a current having a magnitude equivalent to a value obtained by dividing a difference voltage between an input bias voltage, applied to a positive-phase input terminal, and an input signal voltage applied to a negative-phase input terminal, supplied directly with feedback from an output terminal, via a resistor, by resistance of the resistor;
a current mirror circuit that receives the current output by the voltage follower circuit; and
a series circuit connected between ground and an output line of the current mirror circuit, wherein the series circuit includes a load resistor and an output bias voltage source. - View Dependent Claims (7)
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Specification