Patent ID: 7746127

Claim:
A driving device of a capacitive load comprising: a modulator adapted to execute pulse modulation on a drive waveform signal; a digital power amplifier adapted to power-amplify the modulated signal obtained by the modulator with a pair of switching elements push-pull connected to each other; an inductor adapted to low-pass filter the amplified digital signal obtained by the digital power amplifier and output the low-pass filtered signal as a drive signal towards at least one load capacitor as the capacitive load; at least one dummy load capacitor; a load selection control circuit adapted to select the load capacitor and the dummy load capacitor to be connected to the inductor, respectively, so that a sum of a capacitance of the load capacitor and a capacitance of the dummy load capacitor to be connected to the inductor is kept within a predetermined range; and a feedback circuit adapted to execute a filtering process on the drive signal so that a frequency characteristic of a passing band of the drive signal output from the inductor to the load capacitor becomes substantially flat, and feedback the signal obtained to the modulator as a feedback signal, wherein the modulator executes the pulse modulation on a difference value between the drive waveform signal and the feedback signal.