The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 27, 1999
Filed:
Nov. 20, 1996
Manjirnath A Chatterjee, State College, PA (US);
Gregory R Simon, State College, PA (US);
Other;
Abstract
An audio amplifier with a digital input bus for both audio (48) and volume (47) level inputs is disclosed. Volume control is achieved by maintaining dynamic voltage supply rails (43) and (44) to an audio output controller block (45) at a fixed ratio of the maximum available supply voltages (40) and (41). This is accomplished by a volume level controller block (42). The audio output controller block accepts digital samples and converts the samples to analog voltages within the range of the volume rail voltages for the purpose of driving a audio frequency loudspeaker (46). Such a system has very high efficiency when compared with older Class A and AB designs and improves the ease of implementation of volume control over Class D designs. The system is easily distinguished from other designs using variable rail voltages because prior art designs used the rail voltage to track the audio output. The present invention varies the rail voltages for the purpose of controlling the volume of the output and as such relatively large voltages may exist between the output and the voltage supply rails. Also the present invention makes use of all digital inputs whereas prior art does not.