ELECTRONIC APPARATUS

PROBLEM TO BE SOLVED: To supply stable AC output having a little distortion. SOLUTION: The apparatus comprises a PWM converter section 5, a positive voltage rectifying and smoothing section 6, a negative voltage rectifying and smoothing section 7, a power amplification section 10, a PWM controlling section 4, an output driving section 11, a positive error amplification section 8, and a negative error amplification section 9. The PWM converter section 5 consists of a primary winding 5a and secondary windings 5C, 5D of a transformer and a switching element 5B, with a series combination of the primary winding 5a and the switching element 5B connected between both ends of a DC power supply and a tap installed between the secondary windings 5C and 5D. The positive voltage rectifying and smoothing section 6 is connected to one end of the secondary winding 5C and the tap and the negative voltage rectifying and smoothing section 7 is connected to the other end of the secondary winding 5D and the tap. The power amplification section 10 is connected by the positive and negative voltage rectifying and smoothing sections 6, 7. The PWM controlling section 4 drives the switching element 5B based on a signal output from a D/A output section of a CPU section 12 and passed through a sine wave reference signal section 1, a full-wave rectification section 2, and a level shifting section 3. The output driving section 11 drives the power amplification section 10 based on a signal coming through the sine wave reference signal section 1. The positive error amplification section 8 is installed on a feedback path from the positive voltage rectifying and smoothing section 6 to the PWM controlling section 4 and the negative error amplification section 9 is installed on a feedback path from the negative voltage rectifying and smoothing section 7 to the PWM controlling section 4.