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:
Jun. 29, 1982
Filed:
Jul. 28, 1980
Hitachi, Tokyo, JP;
Abstract
A recursive-type digital filter comprising a calculation circuit. The calculation circuit is arranged to multiply an input signal including at least m-bit signal x.sub.n inputted at a predetermined sampling period and an output signal y.sub.n-k fed back to the input of the calculation circuit in accordance with the input signal x.sub.n after being subjected to a delay of k sampling periods by a.sub.k and b.sub.k coefficients corresponding to the filter characteristics, respectively, and then the products are added thereby to produce data y.sub.n of (m+l) bits satisfying, ##EQU1## and serially deliver the upper m-bit data of the data y.sub.n as an output signal corresponding to the input signal x.sub.n. The filter further comprises a delay circuit for feeding back to the input of the calculation circuit a part of the round off data including the upper (m+1)th bit of the data y.sub.n so that the b.sub.k coefficient is multiplied by the fedback data of the upper (m+1)th bit and the product is added to the data y.sub.n, thereby to produce an output signal with reduced round off noise.