| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitive load driving circuit that assures an even output voltage frequency characteristic in a driving frequency band and enables low loss driving, when a capacitive load is driven with a D-class power amplifier. SOLUTION: An LC low-pass filter 15 is provided on the output side of an output stage 14 of a D-class power amplifier, and an output of the LC low-pass filter is applied to a load electrostatic capacity CL through an output transformer T. In this case, a negative feedback circuit 16 feeds back a negative feedback signal from a latter stage of the LC low-pass filter, an error amplification circuit 11 amplifies an error signal between the negative feedback signal and an external input signal VIN, and a modulation circuit 12 pulse-modulates (PWM modulation, PDM modulation, etc.) the amplified error signal. A gate driving circuit 13 generates a gate driving signal of a switching element of the output stage 14 of the D-class power amplifier, and controls ON/OFF of the switching element. COPYRIGHT: (C)2007,JPO&INPIT |
