Accurate capacitor matching measurements using floating gate test structures

Abstract

This paper discusses a new method for characterization of matching of capacitors using the so-called floating gate capacitance measurement method. The paper explains this (DC!!) measurement method and then discusses modifications that were implemented to improve the measurement accuracy and repeatability from its original thousands of ppms (0.1 to 0.3%) to values down to 50 ppm. This improved accuracy is necessary for correct characterization of capacitor matching. The method is demonstrated with results from double-polysilicon capacitor matching measurements.