Pressure and temperature measurement of a piezo-resistive device using differential channel of a ratiometric analog to digital converter

Abstract

A temperature and pressure measuring circuit is provided. The circuit comprises an uncompensated pressure transducer, an analog-to-digital converter, a reference resistive device, and first and second switches. The transducer has variable resistive devices between first, second, third, and fourth bridge nodes. The analog-to-digital converter has first and second reference inputs and first and second differential inputs. When the first switch couples the first differential input and the third bridge node and the second switch couples the second differential input and a ground, a bridge voltage is measurable and a bridge resistance is ratiometrically determinable. The bridge resistance is employed to calculate a temperature. When the first switch couples the first differential input and the first bridge node and the second switch couples the second differential input and the second bridge node, a differential voltage is measurable. The differential voltage is employed to calculate a pressure.