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. 04, 2008
Filed:
Aug. 17, 2005
Christopher G. Regier, Austin, TX (US);
Christopher G. Regier, Austin, TX (US);
National Instruments Corporation, Austin, TX (US);
Abstract
In one embodiment, a differential filter is configured using a differential operational amplifier (op-amp) with two feedback RC networks, each RC network coupled between a respective input and a respective output of the op-amp. Two capacitive elements may each provide mid-band positive feedback from a respective output of the op-amp to the midpoint of a respective corresponding resistive element, where each resistive element is coupled to a respective input of the op-amp. The mid-band positive feedback may operate to convert a first-order response of the filter to a second-order response. In one set of embodiments, dielectric absorption (DA) cancellation may be implemented with positive RC feedback from a divided version of a respective one of the op-amp outputs. For cascaded filters, DA cancellation may be implemented with positive RC feed-forward. Transistors coupled across the feedback RC networks may be used to disable the filter, decoupling the filter from other circuit components when the filter is not in use.