THE MATCHING OF SMALL CAPACITORS FOR ANALOG VLSI - Circuits and Systems, 1996., ISCAS '96, 'Connecting the World'., 1996 IEEE International Symposium

The capacitor has become the dominant passive component for analog circuits designed in standard CMOS processes. Thus, capacitor matching is a primary factor in determining the precision of many analog circuit techniques. In this paper, we present experimental measurements of the mismatch between square capacitors ranging in size from 6 pm x 6 pm to 20 pm x 20 pm fabricated in a standard 2 pm double-poly CMOS process available through MOSIS. For a size of 6 pm x 6 pm, we have found that those capacitors that fell within one standard deviation of the mean matched to better than 1%. For the 20 p m x 20 p m size, we observed that those capacitors that fell within 1 standard deviation of the mean matched to about 0.2%. Finally, we observed the effect of nonidentical surrounds on capacitor matching.