Patent ID: 7078961
Filing Date: 2006-07-18
Classification: H03H

Abstract:
1. A calibration unit for generating a calibration signal for calibrating a filter circuit that has resistor means, capacitor means and amplifier means, wherein the calibration unit comprises: an oscillator circuit comprising reference resistor means, reference capacitor means and reference amplifier means; and means for generating the calibration signal such that the calibration signal is functionally related to a frequency of the oscillator circuit, wherein the means for generating the calibration signal is operatively coupled to the oscillator circuit, wherein: the oscillator circuit further comprises comparator means for generating comparator output pulses based on the frequency of the oscillator circuit, an output of the reference resistor means is coupled to an input of the reference amplifier means and to an input of the reference capacitor means, an output of the reference amplifier means is coupled to an output of the reference capacitor means and to an input of the comparator means, the input of the reference resistor means is selectively coupled to one of two different constant electrical supply potentials, and the comparator means is connected to the calibration-signal generating means.