We present a comparator with signal resolution in the submicrovolt range. The matched pair of transistors is important for maintaining the circuit characteristics. There are equivalents of matched pairs that can be used in this configuration. The operating circuit works without feedback generating a signal compatible with TTL. Schottky diodes act as protection against overdriving and prevent saturation of the output transistor. The circuit operates with a symmetrical 5 V source. In normal applications, one of the input terminals is grounded so that the rejection in common mode is not the greatest. However, the high gain of the OP-50 allows voltage differences of the order of microvolts to be detected. The circuit is not the fastest, but it can detect signal differences in the order of 0.3uV. To obtain more acute transitions, a Schmitt trigger can be used. In figure 1 we have a circuit for this application.
