Dielectric Constant Measurement Circuit and Dielectric Constant Measurement Method

摘要

A dielectric constant measurement circuit includes a dielectric constant sensor, an oscillator controlling circuit, a waveform converting circuit, and a counting readout circuit. The oscillator controlling circuit generates an oscillation waveform according to the response of the dielectric constant sensor to a dielectric material. The waveform converting circuit converts the oscillation waveform into frequency division square waves. The counting readout circuit includes a switching counter, a switching circuit, a reference current source, and a current integrator. The reference current source charges the current integrator through the switching circuit controlled by the frequency division square waves, and the switching counter counts the number of the turned-on states of the switching circuit and stops counting the number of the turned-on states when a value of the output voltage from the current integrator reaches a value of the reference voltage, and the number of the turned-on states is related to the oscillation frequency.

主权项

1. A dielectric constant measurement circuit, comprising:
a dielectric constant sensor; an oscillator controlling circuit electrically connected to the dielectric constant sensor, and comprising an oscillator configured to generate an oscillation waveform according to a variation of a real number part and an imaginary number part in a dielectric constant of a dielectric material when the dielectric constant sensor senses a dielectric material; a waveform converting circuit electrically connected to the oscillator controlling circuit, and configured to convert the oscillation waveform into a plurality of frequency division square waves; and a counting readout circuit electrically connected to the waveform converting circuit, and comprising a switching counter, a switching circuit, a reference current source, and a current integrator, wherein the turned-on/off states of the switching circuit are controlled by the frequency division square waves so that the reference current source charges the current integrator intermittently through the switching circuit, the switching counter counts the number of the turned-on states of the switching circuit, and the switching counter stops counting the number of the turned-on states of the switching circuit when an value of an output voltage from the current integrator reaches a value of a reference voltage, and the number of the turned-on states of the switching circuit is related to an oscillation frequency.