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:
Jan. 25, 1994
Filed:
Sep. 04, 1992
Kenichi Iwanaga, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
The present invention relates to an offset cancellation circuit of digital filtering system which is capable of responding to a variation of an offset value with variation of circuit constant of an A/D converter due to temperature variation, etc. The present offset cancellation circuit is constituted with a low-pass filter for deriving an offset cancellation component from an offset component contained in respective codewords y of output codeword sequence y(kT) (where k is an integer and T is a sampling period of the A/D converter) of a parallel B bits of the offset cancellation circuit at a predetermined ratio every sampling period and accumulating the derived offset cancellation components and an adder for reducing the accumulated offset cancellation components from the input codeword sequence x(kT) of the parallel B bits every sampling period and outputting it as the codeword sequence y(kT). As a result, the whole offset cancellation circuit constitutes a recursive, IIR type digital filter.