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:
Jul. 11, 2006
Filed:
Aug. 13, 2004
Jun Wan, Wilmington, MA (US);
Jun Wan, Wilmington, MA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A charge balancing modulation system for digitizing the output of a variable impedance sensor utilizes synchronous excitation of the input sensor and AC coupling of the analog input signal. In one embodiment, the modulation system includes a switched excitation source for exciting the input sensor and generating an input voltage step in response, and an integrator including an input capacitor, an amplifier and an accumulation capacitor. The input capacitor AC couples the input voltage step to the integrator to form an input charge. A reference charge packet is generated in a data dependent manner and coupled to the integrator simultaneously with the input charge. The integrator integrates charge associated with the sum of the input charge and the reference charge, when applied. The modulation system generates an output data stream exhibiting a ones density proportional to the magnitude of the average input voltage step.