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. 06, 1993
Filed:
Nov. 21, 1991
Tatsuo Fushiki, Hamamatsu, JP;
Sadayuki Narusawa, Hamamatsu, JP;
Yamaha Corporation, , JP;
Abstract
The digital-to-analog converter utilizes a modulator for effecting sigma-delta modulation of multi-bit input data to form a pattern of quantized output data so as to produce a pulse signal corresponding to the input data. The converter is provided with a zero detecting circuit for detecting a silent condition when the input data is continuously held at a zero level. An injecting circuit operates when the silent condition is detected for effecting continuous injection of a fractional reset signal into the modulator to gradually change an internal state of the modulator. A control circuit is provided to detect when the modulator reaches an optimum internal state effective to stabilize a varying idling pattern of the quantized output data for stopping the injection of the fractional reset signal so as to effect convergence of the varying idling pattern into a fixed idling pattern which is substantially free of an audible frequency component under the silent condition.