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:
Feb. 08, 2005
Filed:
Jul. 24, 2003
Toru Ohashi, Saitama-ken, JP;
Yuji Yamamoto, Saitama-ken, JP;
Toru Ohashi, Saitama-ken, JP;
Yuji Yamamoto, Saitama-ken, JP;
Pioneer Corporation, Tokyo, JP;
Abstract
A D/A converter includes a ΔΣmodulator applying Delta-Sigma modulation to a digital signal in order to generate a code sequence, and first and second post-filters as a first-order analog low-pass filter, respectively, which is connected in cascade to the subsequent stage of the modulator, in which low-pass filtering on the code sequence is executed so as to output an analog signal. The post-filter is set to have a cutoff frequency which falls in the frequency range from fca to fHa, where the fca is a cutoff frequecy of the post-filterand the fHa is a maximum frequency thereof. Since the respective attenuation characteristics of post-filters are synthesized, an overall attenuation characteristic between the both filters is able to have the characteristics of a desired second-order filter. The synthesized attenuation characteristic allows the D/A converter to simultaneously execute processing such as de-emphasis in the frequency range between the both cutoff frequency, and elimination of high-frequency noises over the frequency range of the cutoff frequency. As a result, the D/A converter with a small circuit scale can be provided.