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:
Sep. 05, 2000
Filed:
Dec. 04, 1998
Mitsuru Nagata, Kanagawaken, JP;
Kabushiki Kaisha Toshiba, Kawasakishi, JP;
Abstract
There is provided an over-sampling D/A converter which has a mute function for fixing an average DC potential of an analog output signal to a predetermined potential, and comprises a .SIGMA. .DELTA. modulator for receiving a multibit digital signal to which a DC offset value is added and then outputting a one-bit non-return-to-zero signal, a signal generator for receiving the non-return-to-zero signal and the clock signal, then generating a return-to-zero signal which is a logical multiplication of the non-return-to-zero signal and the clock signal and a complementary signal of the return-to-zero signal which is a logical addition of the non-return-to-zero signal and an inverted signal of the clock signal, and then adding the return-to-zero signal to the complementary signal of the return-to-zero signal to thus output a polar-return-to-zero signal, and an analog filter for receiving the polar-return-to-zero signal and then outputting an analog signal. Accordingly, because an average DC potential of an output signal at the time of the mute operation-ON is set substantially equal to the average DC potential of the output signal at the time of the mute operation-OFF, variation in the average DC potential in the output signal due to ON/OFF of the mute operation can be prevented. As a result, generation of audible click noises can be prevented.