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. 23, 1999
Filed:
Apr. 09, 1997
Hideki Wakamatsu, Hyogo, JP;
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
In the prior art multiple calibration standards are required to calibrate multiple measurement ranges in an impedance measuring apparatus and calibration is time-consuming. An impedance measuring apparatus incorporating the invention is provided with a reference resistor part and the relative error among the measurement ranges is corrected automatically using the reference resistor. A single range is calibrated using a single impedance standard so that absolute calibration is carried out for all of the ranges. When correcting the relative error for the various ranges via the reference resistor, measurement takes place at a value smaller than for the full scale of the range and errors caused by resolution, linearity and the S/N ratio are propagated throughout the ranges and accumulate. To prevent this, a signal normalizing part is placed on the front section of an A-D converter and another signal normalizing part is placed on the front section of a frequency converter.