Patent ID: 6940344
Filing Date: 2005-09-06
Classification: H03F

Abstract:
1. A D-class signal amplification circuit supplied with a first power supply voltage, which amplifies an input signal inputted to an input node and outputs an output signal to an output node, comprising: a multiplier that multiplies the input signal by a correction coefficient; a first modulator that executes a delta-sigma modulation to an output signal from the multiplier; a D-class amplifier supplied with the first power supply voltage, which amplifies an output signal from the first modulator to output the output signal to the output node; a voltage conversion circuit that generates a second power supply voltage lower than the first power supply voltage, retained at a constant level from the first power supply voltage; a first low pass filter that inputs a signal converted into a level of the second power supply voltage on the basis of the output signal outputted from the D-class amplifier; a reference signal generation circuit supplied with the second power supply voltage, which generates a reference signal for comparing a signal outputted from the first low pass filter on the basis of the input signal; a second low pass filter that inputs the reference signal; a first comparator that compares a level of the signal outputted from the first low pass filter with a level of the signal outputted from the second low pass filter; and a coefficient control circuit that increases or decreases the correction coefficient being multiplied by the multiplier by a predetermined modifying breadth, on the basis of a comparison result of the first comparator.