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:
Jan. 21, 2003
Filed:
Jun. 04, 2001
Applicant:
Inventor:
Rongtai Wang, Edina, MN (US);
Assignee:
Rosemount Inc., Eden Prairie, MN (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01R 2/726 ;
U.S. Cl.
CPC ...
G01R 2/726 ;
Abstract
An industrial process control transmitter has a capacitive sensor having at least three outputs each responsive in differing amounts to a process condition and to sensor hysteresis. An excitation circuit charges the sensor and pumps the charges to a sigma-delta capacitance-to-digital converter. The excitation circuit includes a charge amplifier coupling one of the sensor outputs to a summing node for summing with a charge on at least one other output. An auto-zeroing switch re-sets the charge amplifier on each cycle of operation of the charge amplifier.