The present invention provides a VCM driver realizing low
power consumption and high accuracy and a PWM
amplifier compensating a
dead time distortion. A phase compensator, a ΔS modulator receiving an output
signal of the phase compensator and converting the output
signal to a control code of predetermined bits, a
PWM modulator receiving the control code to produce a PWM
signal, and an output circuit receiving the PWM signal to drive a
voice coil constitute a forward path. A
sense amplifier sensing a current of the
voice coil, an ADC receiving an output signal of the
sense amplifier, a low-pass filter receiving an output signal of the ADC, and a
decimation filter receiving an output signal of the low-pass filter constitute a feedback path. An output signal of the
decimation filter is fed back to the input side of the phase compensator to form a major
feedback loop having a first-order characteristic
loop gain. An output signal of the
decimation filter is fed back to the output side of the phase compensator to form a minor
feedback loop having a
loop gain which is flat until a target band frequency when viewed from the output side of the phase compensator.