Patent ID: 6930495
Filing Date: 2005-08-16
Classification: G01R

Abstract:
1. A method for sampling and digitizing a resistance measurement from an impedance-varying input sensor, comprising: applying a switched excitation source to said input sensor; generating an input voltage step at said input sensor as a result of said application of said switched excitation source, said input voltage step being indicative of the resistance of said input sensor; AC coupling said input voltage step to an integrator; integrating charges corresponding to a transition of said input voltage step on an accumulation capacitor; generating a fullscale resistance reference signal; applying said fullscale resistance reference signal to said integrator; generating a data dependent signal for deactivating or activating said integrator; integrating a reference charge packet associated with a transition of said fullscale resistance reference signal when said data dependent signal has a first value or disregarding said reference charge packet when said data dependent signal has a second value, said transition of said fullscale resistance reference signal being opposite to said transition of said input voltage step; comparing a signal corresponding to said charges accumulated on said accumulation capacitor with a reference level; and generating an output signal as a result of said comparing, said data dependent signal having said first value and said second value corresponding to respective logical levels of said output signal, wherein after a plurality of sampling cycles, said output signal forms a digital data stream having an ones density proportional to a ratio of the resistance of said input sensor to said fullscale resistance reference signal.