Realization and AC modeling of electronic circuits with water-gated field effect transistors (WG-FETs) based on gate probe distance

We present AC modeling of WG-FET devices based on gate probe distance. Small- and large-signal models are proposed. It is shown that unity gain frequency is inversely proportional to gate distance. Also, common source amplifier, inverter, and ring oscillator circuits are fabricated with WG-FET devices, which use 16 nm-thick mono-Si film as channel layer, for the first time. Circuit simulations are performed based on AC models. Results are verified with experimental measurements using de-ionized (DI) water. For common source amplifier, f _UG is measured as 21 Hz for 2 mm gate distance, and it is increased to 1.2 kHz when gate distance is decreased to 200 μm. For inverter, rail-to-rail operation is observed with t _PLH of 24 ms and t _PHL of 58 ms for 1 square-wave input signal at 1 Hz. Gain is measured as  −11 V/V at switching threshold. Ring oscillator is realized with five inverters. A square-wave output signal with amplitude of 840 and frequency of 2.6 Hz is obtained. AC modeling of WG-FET enables realization of advanced circuits which are inherently compatible with fluidic systems. Therefore, they can be valuable assets especially in microfluidic applications. (paper)