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:
Aug. 14, 2001
Filed:
Jun. 12, 1998
Jinghui Lu, Austin, TX (US);
Oak Technology, Inc., Sunnyvale, CA (US);
Abstract
A voice or data transmission system and specifically an interpolation filter used within the transmission system is provided for producing either fractional or integer interpolation ratios. The digital signal resulting from the interpolation filter has a relatively high signal to noise ratio whenever fractional interpolation is needed. The interpolation filter includes multiple stages coupled in series, and an integer interpolation branch switched in parallel with a fractional interpolation branch. A controller determines whether the integer or fractional interpolation ratio is needed based on maintaining a fixed oversampling data rate from the interpolation filter given a changing incoming sampling rate. If the incoming sampling rate should require fractional interpolation, then a branch implementing fractional interpolation ratio is used in lieu of the integer interpolation ratio. A comb filter is preferably introduced within the fractional interpolation branch to attenuate imaging tones within the baseband of interest. An interpolation rate change switch used by the comb filter beneficially moves the imaging tones further away from the baseband so that minimum imaging noise is introduced within the baseband by the fractional oversampling ratio.