Patent attributes
A ripple filter circuit for ensuring the driving of a driving subject while efficiently eliminating ripple even when the operational voltage margin is small. A first transistor, which is connected to a power supply voltage line, is connected to a ground line via a load of the driving subject. A second transistor, which has substantially the same characteristics as the first transistor, and a dummy load are arranged between the power supply voltage line and the ground line. An operational amplifier includes an inverting input terminal, connected between the second transistor and the dummy load, and a non-inverting terminal at which the voltage is decreased by a predetermined voltage from the power supply voltage. The operational amplifier also includes an output connected to the gate terminal of the second transistor and to the gate terminal of the first transistor via a lowpass filter.
