AMPLIFIER CIRCUIT CONFIGURED INTO INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To reduce the gain peak of a current by deviating the ratio of an input resistance to a feedback resistance in an inductive load driving amplifier circuit by a prescribed degree so as to omit connection of an externally mounted capacitor of a prescribed capacitance or over. SOLUTION: A differential amplifier PA2 receives an output of a differential amplifier PA1 at its inverting input terminal via a resistor R and has a gain of -1. The amplifier PA1, PA2 drive a VCM coil L acting like an inductive load connecting between output pins Po1 and Po2, a current Io flowing to the coil L is sensed by a current sensing resistor Rs to feed back a current to the differential amplifiers PA1, PA2. A resistor R5 with a very small resistance to reduce a gain peak is inserted between a feedback resistor R4 and a sense pin Ps. The current Io flowing to the coil is expressed as (R2/R1).(Vin-Vref)/ Rs, which is independent of the impedance of the coil.