Title :
A digital readout technique for capacitive sensor applications
Author :
Kung, Joseph T. ; Lee, Hae-Seung ; Howe, Roger T.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., MIT, Cambridge, MA, USA
Abstract :
The difference between two capacitors is measured digitally using a charge redistribution technique incorporating a comparator, MOS switches, a successive approximation register, and a digital-to-analog converter. The technique is insensitive to comparator offset and parasitic capacitance, and the effect of MOS switch charge injection is measured and canceled. Extensive measurements have been made from test chips fabricated in 3- mu m CMOS technology. Detection of percent differences of <0.5% on 20-100-fF capacitors has been successfully demonstrated.<>
Keywords :
CMOS integrated circuits; capacitance measurement; digital readout; electric sensing devices; 20 to 100 fF; 3 micron; CMOS technology; D/A convertor; MOS switch charge injection; MOS switches; capacitive sensor; charge redistribution technique; comparator; digital readout technique; monolithic type; successive approximation register; CMOS technology; Capacitive sensors; Charge measurement; Current measurement; Digital-analog conversion; MOS capacitors; Parasitic capacitance; Registers; Semiconductor device measurement; Switches;
Journal_Title :
Solid-State Circuits, IEEE Journal of
