A MOSFET-only second order delta-sigma modulator for capacitive sensor interfaces

A 14-bit MOSFET-only 2/sup nd/ order /spl Delta/-/spl Sigma/ modulator has been implemented in a 0.7 /spl mu/m CMOS process for capacitive sensors interfaces. A switched capacitor architecture that allows the substitution of linear capacitors by MOS capacitors has been developed. These circuits have low cost fabrication, small area, and high matching. This proposal was tested comparing two different /spl Delta/-/spl Sigma/ modulators, one with linear capacitors and the MOS-only version. Similar results were obtained for both modulators.