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. 15, 2011
Filed:
Sep. 04, 2008
Robert Remmers, Altdorf, DE;
John Vogt, Denton, TX (US);
Robert Remmers, Altdorf, DE;
John Vogt, Denton, TX (US);
Texas Instruments Deutschland GmbH, Freising, DE;
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A switched capacitor measurement circuit is provided for measuring the capacitance of an input capacitor with a parallel parasitic resistor. The circuit comprises a switching arrangement, a reference capacitor, a steered current sink and an operational amplifier with an output, a non-inverting input connected to a reference voltage source and an inverting input connected to a first terminal of the input capacitor. The current sink is steered to compensate for a charge current due to the parasitic resistor. Still further, the circuit comprises a digital adder and an analog-to-digital converter with an analog input connected to the output of the operational amplifier and a digital output connected to a first input of the digital adder. A second input of the digital adder receives a negative digital error signal and the output of the digital adder provides a digital capacitance measurement signal corrected for an error current which is integrated across the reference capacitor in the gain mode due to the slewing of the operational amplifier.