Yamaha Corporation

Yohei Otani

Masao Noro

Morito Morishima

Nobuaki H Tsuji

Hirotaka Kawai

A power amplifier includes a class-D amplifier and an input signal supplier. The class-D amplifier includes an input portion and a switching device. The switching device is switched according to an input signal that is input to the input portion so that a current is supplied to a load from a power source via the switching device. The input signal supplier supplies the input signal to the input portion of the class-D amplifier, calculates a virtual output voltage to be output from a virtual power source having a prescribed internal impedance characteristic when a current to flow through the load is output from the virtual power source, and adjust an amplitude of the input signal according to the virtual output voltage.

Power amplifier and input signal adjusting method

A power amplifier includes a class D amplification section and a load current feedback circuit. The class D amplification section includes an input section and a switching section serving as an output stage and switched depending on a signal input to the input section, and outputs current from a power source to a load via the switching section. The load current feedback circuit negatively feeds back the current flowing in the load to the input section of the class D amplification section.

Power amplifier

The present invention provides a D/A converter circuit which enables D/A conversion with a high precision and can prevent occurrence of a limit cycle component in the case where an input signal is low, and can also prevent the effect of dither signal from occurring in an analog signal which is a D/A conversion result. A dither signal generation sectionoutputs a dither signal (DITHER) which is an alternating current signal and a reversal dither signal (DITHER_N) inverted from the dither signal. A DEM decoderprocesses an input digital signal including a component of the dither signal (DITHER), and outputs a plurality of lines of time-series digital signals having a density of '1' or '0' conforming to the input digital signal to be processed. An analog addition sectionconverts a plurality of lines of time-series digital signals and the reversal dither signal (DITHER_N) into an analog signal respectively and adds them, and outputs an analog signal which is a D/A conversion result.

Growing community of inventors

Hamamatsu, Japan

Yohei Otani