CMOS stress sensor circuits using piezoresistive field-effect transistors (PIFETs)

CMOS analog stress sensor circuits based upon the piezoresistive behavior of MOSFETs are proposed. On the (100) surface, these circuits provide temperature compensated output voltages and currents that are proportional to the inplane normal stress difference (/spl sigma//sub 11//sup -/-/spl sigma//sub 22//sup -/) and the in-plane shear stress /spl sigma//sub 12//sup -/ The circuits offer high sensitivity to stress, highly localized stress measurement and provide direct voltage or current outputs, eliminating the need for tedious /spl Delta/R/R measurements required with more traditional resistor rosettes.