The floating gate measurement technique for characterization of capacitor matching

This paper discusses a new method for characterization of matching of capacitors using the so-called floating gate capacitance measurement method. After an introduction of this measurement method, modifications are discussed that were implemented to boost the measurement accuracy and repeatability from its original thousands of ppm´s (0.1 to 0.3%) to values as low as 50 ppm (0.005%). Instrumental in these improvements are the introduction of a double slope measurement procedure to compensate for systematic offsets, as well as the use of repeated measurements and averaging to reduce the influence of the measurements system´s noise. The improved accuracy, including statistical characterization of the measurement system´s short term repeatability, are required for correct determination of capacitor matching of the extremely well-matching double-polysilicon capacitor structures that were used for this study