Design of a window comparator with adaptive error threshold for online testing applications

This paper presents a novel window comparator circuit whose error threshold adjusts adaptively with respect to its input signal levels. Advantages of adaptive error thresholds over constant or relative error thresholds in analog testing applications are discussed. Analytical equations for guiding the design of the comparator circuitry are derived. The proposed comparator circuit has been designed and fabricated using a CMOS 0.18μm technology. Measurement results of the fabricated chip are presented.