Patent ID: 7239200
Filing Date: 2007-07-03
Classification: H03F

Abstract:
1. A power amplifying apparatus comprising: a switch unit that is supplied with a power supply voltage Vc and includes a series circuit of a high-side switch and a low-side switch; and a control unit that operates the switch unit in accordance with the input AC signal Vi in a cycle with a predetermined ratio of ON and OFF periods to drive a load connected to a connection point between the high-side switch and the low-side switch, the control unit including: a pulse modulation unit that receives the input AC signal Vi, generates a pulse signal from the input AC signal Vi at a predetermined modulation sensitivity, and outputs the pulse signal; an arithmetic unit that detects a DC voltage component (Ec) from the power supply voltage Vc, and that multiplies the modulation sensitivity by a ratio (Vc/Ec) of the power supply voltage (Vc) to the DC component (Ec) or multiplies the input AC signal Vi by a ratio (Ec/Vc) of the DC component (Ec) to the power supply voltage (Vc); and a drive unit that drives the switch unit on the basis of the pulse signal.