US Patent 9423438 Dielectric constant measurement circuit and dielectric constant measurement method

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.