Patent ID: 6194946
Filing Date: 2001-02-27
Classification: G06G,G11C

Abstract:
A lossy integrator comprising in combination:(a) an operational amplifier having an inverting input coupled to a summing conductor, a non-inverting input coupled to receive a first reference voltage, and an integrating capacitor coupled between the inverting input and an output conductor of the operational amplifier;(b) a switched capacitor feedback circuit coupled between the output conductor and the inverting input of the operational amplifier, the switched capacitor feedback circuit includingi. first and second feedback capacitors,ii. first and second sampling switches coupling the first feedback capacitor between the summing conductor and the output conductor during a first clock signal, and first and second reset switches respectively coupling the terminals of the first feedback capacitor to the first reference voltage during a second clock signal,iii. third and fourth sampling switches coupling the second feedback capacitor between the summing conductor and the output conductor during the second clock signal, and third and fourth reset switches coupling the terminals of the second feedback capacitor to the first reference voltage during the first clock signal,the orientations of the first and second feedback capacitors being opposite to effectuate cancelling of voltage coefficient error charge contributions into the summing conductor from the first and second feedback capacitors.