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:
Nov. 02, 1999
Filed:
Feb. 13, 1998
Takayuki Kohdaka, Hamamatsu, JP;
Mituhiro Homme, Hamamatsu, JP;
Masamitu Hirano, Hamamatsu, JP;
Tatsuya Kishii, Hamamatsu, JP;
Kuniaki Morita, Hamamatsu, JP;
Juhro Hoshi, Hamamatsu, JP;
Yamaha Corporation, , JP;
Abstract
The digital-to-analog conversion apparatus operates to convert an digital input into a corresponding analog output. A digital filter is provided for oversampling the digital input having a varying value represented in the form of multiple bits. A delta-sigma modulator operates to effect delta-sigma modulation of the oversampled digital input to reduce a number of the multiple bits for requantizing the oversampled digital input with a certain S/N ratio. A low-pass filter is provided for converting the requantized digital input into an analog output. A level detecting circuit is provided for detecting when the value of the digital input falls below a predetermined level. A shifting circuit is disposed upstream of the delta-sigma modulator and is responsive to the detected results for increasing the value of the digital input so as to improve the S/N ratio in the delta-sigma modulator. An attenuator is disposed downstream of the delta-sigma modulator and is responsive to the detected results for effecting decreasing compensation for the increased value of the digital input while substantially maintaining the improved S/N ratio so as to produce an analog output corresponding to the digital input.