Offset Cancellation Circuit

Abstract

An offset cancel circuit includes a first amplifying section, a second amplifying section, a third resistor connected between a non-inverting input terminal of the first amplifying section and a non-inverting input terminal of the second amplifying section, and a current source. In the offset cancel circuit, the current source causes a constant current to flow through the third resistor to cancel an offset voltage from output signals of first and second amplifying sections, the constant current corresponding to the offset voltage contained in first and second output signals output from a bridge resistance type sensor.

Description

technical field [0001] The present disclosure relates to an offset cancellation circuit capable of canceling an offset voltage contained in an output signal of a bridged resistance type sensor configured by connecting a plurality of resistance elements by bridges. Background technique [0002] In general, a magnetic sensor in which a plurality of GMR elements (giant magnetoresistance effect elements) are bridged (for example, JP-A-2007-212275) is known. In the GMR element, according to an external magnetic field, the magnetization direction of the free layer is relatively rotated with respect to the fixed magnetization direction of the pinned layer, so that the resistance is changed. When focusing on the electrical characteristics of the GMR element, the GMR element is a type of resistive element. Therefore, in the case where a plurality of GMR elements constitute a bridge circuit, it is possible to sense an external magnetic field through a change in the potential balance ...

AI Technical Summary

Problems solved by technology

Therefore, the related offset cancellation circuit 95 has a problem in that it is difficult to sufficiently generate a voltage drop corresponding to the dispersion of resistance in the bridge circuit in an arbitrary temperature range, and can cancel the offset voltage Voff only at a specific temperature

[0006] This problem is not limited to the magnetic sensor 90 configured by bridging a plurality of GMR elements 91 to 94, but this problem is also applied to a bridged resistance type sensor in which a plurality of resistance elements are bridged.

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