A fast latching current comparator for 12-bit A/D applications

Describes a novel monolithic high-speed comparator which senses the polarity of the input current rather than voltage. The new approach greatly reduces overall system conversion time for a successive approximation 12-bit A/D converter. The circuit features a single input pin for polarity discrimination, dual complementary outputs, and fast response time of 72 ns to 0.5 LSB overdrive (500 nA). The sum of the total error due to the comparator is 0.2 LSB with respect to the input. The comparator is manufactured on a bipolar, ion-implanted base, 9 /spl mu/m epi, junction-isolated process.