Mismatch Characterization of Small Metal Fringe Capacitors

Even though small metal fringe capacitors are important for the realization of a variety of circuits, including low-energy analog-to-digital converters and digitally controlled oscillators, the present literature is lacking experimental data on their mismatch characteristics. This paper describes a test structure and measurement results pertaining to the characterization of single-layer, lateral-field, 0.45-fF and 1.2-fF unit metal capacitors in a 32-nm SOI CMOS process. The measurement-inferred average standard deviations for these capacitances are 1.2% and 0.8%, respectively, confirming area scaling according to Pelgrom's matching formula.