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:
Nov. 13, 2001
Filed:
Jul. 01, 1998
Dennis K. Briefer, Marlborough, MA (US);
Setra Systems, Inc., Boxborough, MA (US);
Abstract
A capacitance measurement system amenable to implementation on an integrated circuit includes a switching network, a voltage driving element, a sensor network, and a feedback network. The sensor network includes a fixed capacitor connected in series to a variable sensing capacitor. The feedback network receives the voltage generated at the junction node between the two capacitors, and the other side of the sensor capacitor is connected to system ground. The voltage driving element, responsive to a signal from the switching network, shifts the local voltage which supplies power to the feedback network. The feedback network generates a feedback signal representative of the difference in the charge stored on the series capacitors from a predetermined value. The switching network includes a control which is operative to cyclically interconnect the feedback signal and reference potentials with the sensor network and the voltage driving element, whereby the average change in the charge stored on the capacitors over each cycle is substantially equal to the predetermined value. In this configuration, the feedback signal is a predetermined function of capacitance of the sensing capacitor.