Patent ID: 7825604
Filing Date: 2010-11-02
Classification: H03F

Abstract:
1. A drive circuit to supply a current to a load based on a control signal, the drive circuit comprising: an operational amplifier to compare a voltage applied to a first input terminal with a reference voltage applied to a second input terminal; a first transistor to supply a current to said load depending on a comparison result of the operational amplifier; a second transistor to provide an output current depending on the comparison result of the operational amplifier; a first switch to switch, based on the control signal, between outputting the comparison result of the operational amplifier to the first transistor and outputting a predetermined voltage to the first transistor to turn off the first transistor; a second switch to switch, based on the control signal, between connecting an output of the first transistor to the first input terminal of the operational amplifier and connecting an output of the second transistor to the first input terminal of the operational amplifier; and a third switch to switch, based on said control signal, between outputting the comparison result of said operational amplifier to said second transistor and outputting the predetermined voltage to said second transistor to turn off said second transistor.