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. 12, 1991
Filed:
Dec. 15, 1989
Robert A Parks, Springport, IN (US);
Boehringer Mannheim Corporation, Indianapolis, IN (US);
Abstract
An analog-to-digital converter employs a capacitor circuit for integrating a sample of an input signal during a predetermined interval of time and, thereafter, the capacitor is discharged at a predetermined rate until the integration voltage is equal to that of a reference. The discharge time serves as a measure of the amplitude of the input signal. A measurement interval is established which is equal to an integral number of cycles of each of the possible values of frequency of the A.C. excitation. The signal integration interval has a duration less than or approximately equal to the shortest period of the A.C. excitation, this being the period of the highest frequency A.C. excitation. The signal integration is repeated periodically at each third half-cycle of the highest frequency excitation so that the total integration time experienced during positive half cycles is equal to that experienced during negative half cycles of any of the plurality of excitation frequencies. This cancels the effect of noise due to signal polarity.