Abstract: A method for determining the deterioration of a capacitor that increases the measurement accuracy to have an improved reliability is disclosed. In this method for determining the deterioration of a capacitor, the deterioration of a capacitor including a pair of electrode bodies and electrolytic solution provided between the electrode bodies is determined by applying an AC voltage to the capacitor to measure an impedance characteristic at a frequency of the AC voltage. An inflection point appearing in the impedance characteristic due to the deterioration of the electrolytic solution is previously calculated to make comparison with an impedance value in the frequency region lower than the inflection point, thereby determining the deterioration.

Abstract: A method for determining the deterioration of a capacitor that increases the measurement accuracy to have an improved reliability is disclosed. In this method for determining the deterioration of a capacitor, the deterioration of a capacitor including a pair of electrode bodies and electrolytic solution provided between the electrode bodies is determined by applying an AC voltage to the capacitor to measure an impedance characteristic at a frequency of the AC voltage. An inflection point appearing in the impedance characteristic due to the deterioration of the electrolytic solution is previously calculated to make comparison with an impedance value in the frequency region lower than the inflection point, thereby determining the deterioration.

Abstract: A pulse-width modulation amplifier includes a triangular signal oscillator for generating a triangular carrier signal. A voltage comparator compares an input analog signal and the triangular carrier signal, and converts the input analog signal into a corresponding pulse-width modulation signal. A power amplifier serves to amplify the pulse-width modulation signal. A low pass filter removes carrier components from an output signal of the power amplifier, and generates a demodulated signal corresponding to the input analog signal. The amplitude of the triangular carrier signal is controlled in response to a power supply voltage fed to the power amplifier so that the amplitude of the triangular carrier signal will be substantially proportional to the power supply voltage.