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:
Mar. 30, 1999
Filed:
Oct. 06, 1997
Motorola Inc., Austin, TX (US);
Abstract
An analog-to-digital converter (100) has a first path (110) with a first sigma-delta modulator (114) which transforms an analog input signal X.sub.0 (111') from an input terminal (101) to a digital output signal Y.sub.0 at an output terminal (102). In a second path (120), a digital dither signal D (121') is combined with a digital intermediate signal Z.sub.0 (115') from the first modulator (114) and digitally processed by a second sigma-delta modulator (124) to an intermediate signal Y.sub.1 (125') Y.sub.1 is fed to the first modulator (114) and to the output terminal (102) with opposite sign ('+' and '-', respectively). Thereby, multipliers (133 and 127) attenuate Y.sub.1. The dither signal D (121') is used substantially only within the converter (100), and is substantially canceled before the output terminal (102). This features preserve a high SNR of the converter (100) and low spectral tones in output signal Y.sub.0.