Circuit arrangement to convert digital value into DC signal - has fixed and variable capacitors in AC bridge circuit with rectifiers and differential amplifier

摘要

The circuit arrangement comprises a capacitative sensor with two capacitors, an oscillator with an inductively coupled output, a rectifier circuit and an alternating current supply circuit. One capacitor (16) has a value which is variable in dependence on the value of the physical quantity and the other (18) has a fixed value. The capacitors are each coupled through a diode (D1, D2) with a secondary winding 22, 24) of the current supply circuit and with a resistor (R1, R2) forming a bridge circuit with diagonal connections to a feedback differential amplifier (38) which is followed later by a second stage amplifier (40).