Offset reducing circuit for differential amplifier
AssigneeRohm Co., Ltd.
InventorShigeyoshi Hayashi
Life of this patent
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Abstract
A differential amplifier includes a differential couple in which emitters of a pair of transistors are connected by a resistor. A voltage difference between bases or emitters of the transistors is detected, and a current responding to the voltage difference is fed back to the differential couple from a current canceling circuit to cancel a current which causes the voltage difference. As a result, an offset generated between inputs of a differential amplifier due to differences between constant currents is reduced.
Claims6
A voltage offset reducing circuit which reduces a voltage differential produced between two transistors of a differential amplifier, said voltage differential being produced by an imbalance in current supplied to a differential couple, comprising:
- a current mirror circuit disposed on a collector side of said two transistors of said differential amplifier, for supplying a current to one of said two transistors which corresponds to a current flowing through the other of said two transistors;
- a differential amplifier including a resistor connected between emitters of the two transistors to form said differential couple;
- and
- a current canceling circuit for detecting a voltage differential between bases of said two transistors, configured to supply a current responsive to said voltage differential to said differential amplifier, thus acting to cancel said current imbalance responsible for causing said voltage differential.
A voltage offset reducing circuit which reduces a voltage differential produced between two transistors of a differential amplifier, said voltage differential being produced by an imbalance in current supplied to a differential couple, comprising:
- a current mirror circuit disposed on a collector side of said two transistors of said differential amplifier, for supplying a current to one of said two transistors which corresponds to a current flowing through the other of said two transistors;
- a differential amplifier including a resistor connected between emitters of the two transistors to form said differential couple;
- and
- a current canceling circuit for detecting a voltage differential between said emitters of said two transistors of said differential amplifier, configured to supply a current responsive to said voltage differential to said differential, thus acting to cancel said current imbalance responsible for causing said voltage differential.
Dependencies are inferred from the claim text.