Трансимпедансный преобразователь для высокоомных сенсоров, использующий МОП-фотоварикап

<jats:p>Multielement sensors sensitive to various types of radiation, particle fluxes, and gas concentrations with high resistance are currently being actively developed. To record low current signals from resistive sensors, a specialized interface — an electrometric amplifier — is proposed. This interface utilizes a metal–oxide–semiconductor (MOS) structure, which acts as a dynamic capacitor in an optocoupler as a modulating device. This study analyzes the key characteristics of a new dynamic capacitor using a surface-mounted MOS photovaricap as a modulating element for detecting signals from high-resistance sensors. The surface-mounted MOS photovaricaps were fabricated on high-resistance p-type silicon substrates with a thin insulating SiO₂ layer and a translucent metal electrode. Capacitance modulation during transimpedance conversion was achieved by illuminating the photovaricap optocoupler with a light-emitting diode, resulting in an alternating voltage across a load resistor, which was subsequently amplified and recorded. The results show that MOS-photovaricaps can be effectively used to record low DC currents and voltages from high-impedance sensors. This approach allows this electrometric amplifier to be used for, for example, recording slowly changing value, for example, gas concentrations, several species of radiation, particle beams et cetera.</jats:p>