Low power operational amplifier
AssigneeSamsung Electronics Co., Ltd.
InventorKyu-young CHUNG
Life of this patent
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Abstract
An amplifier which operates with low power is provided. In the amplifier, a first input unit includes a first control circuit and a second control circuit each including one terminal connected to an output node and the other terminal connected to a respective input transistor from among the plurality of input transistors, and controls the amount of current flowing into the plurality of input transistors or flowing out of the plurality of input transistors according to operating modes of the amplifier, whereby even when an A bias current is increased in order to increase a slew rate of the amplifier, a B bias current a the quiescent current do not increase.
Claims17
A folded cascode amplifier including a class-AB input terminal, the amplifier comprising:
- a first input unit to receive a first an A bias current, to transform a difference between an input voltage and an output voltage of the amplifier into a corresponding intermediate current, and comprising a plurality of input transistors;
- a second input unit to receive the intermediate current and a B bias current and to control a voltage output from the second input unit in response to a change in the intermediate current from the first input unit;
- and
- an output unit to output an output voltage to an output node controlled by an output control unit which receives the output voltage of the second input unit, and to generate a quiescent current to flow from the output control unit to a ground voltage source,
- wherein the first input unit comprises a first control circuit and a second control circuit each comprising one terminal connected to the output node and another terminal connected to a respective input transistor from among the plurality of input transistors, and
- wherein each of the first and second control circuits controls a current flowing into the plurality of input transistors and out of the plurality of input transistors, according to respective operating modes of the amplifier, whereby the B bias current and the quiescent current do not increase even when the A bias current is increased to increase a slew rate of the amplifier.
An amplifier, comprising:
- a first input unit to receive a first voltage and convert the first voltage into a first current, the input unit comprising:
- a plurality of input transistors;
- a first control unit comprising:
- a plurality of first control transistors connected between a first current source and a first input transistor;
- and
- a plurality of second control transistors connected between the first current source and an output of the amplifier;
- and
- a second control unit comprising:
- a plurality of third control transistors connected between a second current source and a second input transistor;
- and
- a plurality of fourth control transistors connected between the second current source and the output of the amplifier;
- a second input unit to receive the first current from the first input unit and to convert the first current into a second voltage;
- and
- an output unit to receive the second voltage from the second input unit and to convert the second voltage into an output voltage.
Dependencies are inferred from the claim text.