A Digital Readout Technique for Capacitive Sensor Applications
نویسنده
چکیده
The difference between two capacitors is measured digitally using a charge redistribution techrdque incorporating a comparator, MOS switches, a successive approximation register (SAR), and a dlgital-to-anaIog converter (DAC). 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-pm CMOS technology. Detection of percent dit’fereuces of less than 0.5 percent on 20100-fF capacitors has been successfully demonstrated.
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