Patent ID: 7385547
Filing Date: 2008-06-10
Classification: H03M

Abstract:
1. A method of operating an image sensor, said method comprising: applying a first analog input signal to the first side of a first crow bar capacitor, and a second analog input signal to the first side of a second crow bar capacitor; applying a voltage common reference signal to the second side of the first crow bar capacitor, and to the second side of the second crow bar capacitor; generating a first differential input signal from the voltages on the first crow bar capacitor and a second differential input signal from the voltages on the second crow bar capacitor; applying the first differential input signal to a first input line of a differential comparator; applying the second differential input signal to a second input line of the differential comparator; generating a first digital-to-analog converter analog output value based on an output from the differential comparator; generating a second digital-to-analog converter analog output value based on said output from the differential comparator; generating a third differential input signal based on the first digital-to-analog converter analog output value and a fourth differential input signal based on the second digital-to-analog converter analog output value; applying the third differential input signal to a third input line of the differential comparator; applying the fourth differential input signal to a fourth input line of the differential comparator; and generating a digital output value from the differential comparator based on a comparison of the first differential input signal and the second differential input signal.