Abstract: A fixed reference capacitance (10) and a variable, pressure sensitive capacitance (12) are defined by a common conductive layer (14), and a common dielectric layer (16). A peripheral conductive layer 20 completes the reference capacitor and a central conductive layer (22) completes the variable capacitor. A peripheral supporting layer or structure (18) prevents the thickness or the dielectric constant of the dielectric layer peripheral portion but not the central portion from varying in response to pressure changes. In this manner, the reference and variable capacitors may be placed closely adjacent without pressure isolating the reference capacitor. An oscillator (30) provides an AC, such as square wave, driving signal to first and second temporary storage capacitors (52, 54). A bridge (70) of CMOS transistors selectively connects the first and second storage capacitors with the reference and variable capacitors.