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:
Apr. 04, 2017
Filed:
Nov. 20, 2015
Freescale Semiconductor, Inc., Austin, TX (US);
FREESCALE SEMICONDUCTOR, INC., Austin, TX (US);
Abstract
In a touch interface, a sensor provides an output signal that is a function of a sensed capacitance. The sensor includes a charger for repetitively applying first and second voltages to charge the sensed capacitance to first and second charge values in first and second phases respectively. A sampler includes a first current mirror for providing first and second sample current signals that are a function of the first and second charge values respectively. An accumulator uses an accumulator signal to provide the output signal. The accumulator repetitively uses the first and second sample current signals differentially to modify a charge on an accumulator capacitor and provide the accumulator signal. The accumulator signal is a progressive function of the sensed capacitance but cancels noise in the first and second sample signals at frequencies less than a repetition rate of operation of the accumulator.