Patent ID: 7545181
Filing Date: 2009-06-09
Classification: H03K

Abstract:
1. A comparator system for sensing an analog input signal level and for producing a digital output signal, the comparator system comprising: first reference means for providing a first reference level to which said analog input signal level is to be compared, second reference means for providing a second reference level different from said first reference level, first comparator means for comparing said analog input signal level to said second reference level, a control signal responsive to said first comparator means, amplifier system means responsive to said control signal that selects said amplifier system operation in either amplify mode or offset zero mode, said amplifier system means having an offset voltage, said amplifier system means when in said amplify mode amplifying with error caused by said offset voltage the difference in level between said input signal and said first reference level, second comparator means for producing a digital output signal with value dependent on said amplifier system means' output level when in said amplify mode, storage means for storing when said amplifier system means is in said offset zero mode a correction signal at a level that reduces said error, and circuit means for applying said correction signal to said amplifier system means when in said amplify mode to reduce said error whereby the said comparator system has reduced offset voltage.