Yamaha Corporation

Toshihiko Kawano

Kiyoto Kuroiwa

Ryuuji Wakatsuki

A D/A conversion apparatus includes a DSP which receives and converts input digital data with different conversion factors, to generate a plurality of digital data having different levels, selects one of the plurality of the generated digital data, depending upon the signal quality of the input digital data, while attenuating the other digital data to be lower than a predetermined noise level. A plurality of D/A converting devices convert the respective generated digital data into corresponding analog signals. A re-converting device converts the level of each of the analog signals into an original level, based on a corresponding one of the conversion factors with which the input digital data is converted by the DSP. An adding device adds the re-converted analog signals. An attenuating device attenuates, in an input stage of the adding device, medium-to-high frequency components of at least one of the analog signals generated by at least one of the D/A converting devices that receives the attenuated digital data, and corresponding to digital data obtained by converting the input digital data with a smaller conversion factor than that of the digital data selected and generated by the DSP.

DA conversion apparatus to reduce transient noise upon switching of analog signals

A floating type analog-to-digital converter which is capable of converting an analog signal into a digital signal in a wide dynamic range, while exhibiting stable frequency characteristics due to the presence of symmetric pre-echo and post-echo in the impulse response waveform. An analog signal level adjusting device adjusts the level of an analog signal with different first gains, so as to generate a plurality of analog signals of different levels for analog-to-digital conversion. A plurality of analog-to-digital converters convert respective ones of the plurality of analog signals generated from the analog signal level adjusting device, into respective digital signals, and output the digital signals. A digital signal level adjusting device adjusts the levels of the digital signals with different second gains corresponding to respective inverses of the first gains, and generates the adjusted digital signals, which are then delayed and generated by a delay device. A switching device selects one of the digital signals generated from the delay device, based on the level of one digital signal selected from the digital signals generated from the plurality of analog-to-digital converters, and generates the selected one digital signal.

Floating type analog-to-digital converter using delay units to achieve a

A power source apparatus comprises a DC power source, a switching element, and a controller for performing an ON/OFF operation of said switching element at a predetermined switching frequency. The power source apparatus chops an output from the DC power source to control a DC output to be supplied to a load, or temporarily converts the output from the DC power source into an AC voltage to transform the DC voltage and supplies the transformed voltage to said load. The controller includes an external clock input terminal and a sync circuit for causing the switching frequency to coincide with a frequency of a clock applied to said external clock input terminal or a frequency which is an integer multiple of the frequency of the clock.

Growing community of inventors

Tokushima-ken, Japan

Toshihiko Kawano