POWER AMPLIFIER

PURPOSE:To generate a pulse width modulation signal with excellent linearity by providing a control circuit controlling the amplitude of a triangle wave carrier signal output from a triangle wave generating circuit and a power voltage fed to an output amplifier in response to the amplitude of an analog signal. CONSTITUTION:The amplitude of a triangle wave carrier signal generated from a triangle wave generating circuit 3 is controlled with a control signal outputted from a control circuit 10. In terms of the triangle wave carrier signal, in spite of the amplitude change of an analog signal, the control signal controls the amplitude of the triangle wave carrier signal so as to always compare the triangle wave carrier signal with a modulation signal in a region of excellent characteristic. Then the modulation signal and the triangle wave carrier signal inputted to the comparator circuit 4 are compared in the comparator circuit 4, from which a pulse width modulation signal is outputted in response to the analog signal. Since the pulse width modulation signal is generated by comparing the triangle wave carrier signal with the modulation signal at a region with an excellent linearly of the triangle wave carrier signal, an ideal pulse width modulation signal without distortion is obtained.