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:
Mar. 20, 2001
Filed:
Sep. 06, 2000
Mitsuru Nagata, Naka-gun, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A 1-bit D/A converter with a zero detect soft mute function is provided in such a manner that a counter is operated by detecting that a multibit digital signal is all zero for a constant period of time, and a feedback resistor of an op-amp in the analog low-pass filter is decreased stepwise based on a discrete value of the counter so as to be finally short-circuited so that a D/A convert output is fixed at a reference potential. The feedback resistor is composed of a plurality of resistors of first and second groups and first to third analog switches. A first digital control variable resistor is constituted by connecting the resistors of the first group in series and connecting a first analog switch selectively turned on/off in accordance with an output signal other than an LSB of the counter to respective nodes. A second digital control variable resistor is constituted by connecting the resistors of the second group in parallel and connecting a second analog switch controlled by the LSB of the counter to one side resistor in series. The first and second digital control variable resistors are connected in series, and a third analog switch is connected to both ends so as to constitute a feedback resistor.