ALEXANDRIA, Va., June 16 -- United States Patent no. 12,309,556, issued on May 20, was assigned to ROHM Co. LTD. (Kyoto, Japan).
"Audio circuit" was invented by Mitsuteru Sakai (Kyoto, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "An audio circuit is configured to allow an analog voltage to be input via its volume setting pin. A power supply pin receives a power supply voltage. A bias circuit generates a first reference voltage that corresponds to the analog voltage. A D/A converter converts a digital audio signal into an analog audio signal. AD/A converter has a variable voltage range with a full scale that can be changed according to the first reference voltage. A class D amplifier outputs an output...