CAPACITIVE PRESSURE TRANSDUCER SYSTEM

摘要

A capactive ratioing oscillator circuit utilizing a prior art pressure capsule, but through modification of the stable variable oscillator circuit achieves a digital output which varies with the square root of the capacitance ratio C35 Cp/Cr. In this sensor the dielectric constant of the pressure media is measured in time with the pressure difference measurement. The oscillator includes a differentiator inverter step herein each of capacitors Cr and Cp are connected to a common point and resistors are connected in parallel with each of said capacitors and with the common point connected to the inverting terminal of a first operational amplifier, a feedback line is connected from the output of the operational amplifier to the second resistor opposite the common point, first and second integrator circuits are connected to the output of said operational amplifier, a limit circuit is connected across the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit to the input of the inverter stage.