Patent ID: 7571065
Filing Date: 2009-08-04
Classification: G01D

Abstract:
1. A method for providing calibration of capacitive sensor signals in a capacitive sensor having a capacitive measuring sensor and a capacitive reference sensor, the method comprising: receiving a capacitive sensor signal and a capacitive reference signal from the capacitive measuring sensor and the capacitive reference sensor, respectively; generating a first compensation signal to the sensor signal based on a gain characteristic wherein the gain circuit generates an output, Vout, obeying the following equation: where: Cp is a measured capacitance from the capacitive sensor; Cr is a reference capacitance from the reference sensor; α β is a gain component; and Vdd is a supply voltage; generating a second compensation signal to the reference signal based on the gain characteristic and an offset characteristic; combining the first compensation signal and the capacitive sensor signal, and the second compensation signal and the capacitive reference signal to create a compensated sensor signal; and, adjusting the compensated signal for temperature effects by coupling a component having a high thermal coefficient to the sensor.