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For large-area electronic applications, the mechanism of the leakage current in oxide-semiconductor thin-film transistors (TFTs) has become a critical issue. In this work, the impact of the irradiation location on the photo-leakage current of zinc oxide (ZnO) TFTs is investigated. The photo-leakage current of the ZnO TFTs is not only dependent on the light irradiation but it is also dependent on the parasitic capacitance between the drain electrode and the floating gate metal. The photo-leakage current of the source-half irradiation TFT is larger than that of the drain-half irradiation TFT. To explain this phenomenon, the profile of the electric potential and the electron concentration is analyzed by two-dimensional device simulation. It is found that the floating gate metal plays the dominant role in the photo-leakage current. This research provides insight into TFT structure optimization and high-performance TFT process development. [ABSTRACT FROM AUTHOR]

A peak-voltage detection circuit based on a differential comparison structure is proposed to synchronize the control and the input signal. The detection circuit is hence free of reset signals for the sampling capacitors. Furthermore, a two-channel parallel sample and hold structure (i.e., S/H circuit) is used, and a correlated double sampling technique is used, in combination with the ping-pong technique, to sample the signal value and offset voltage within one sample cycle. Consequently, the parallel connected S/H structure can not only extract the offset voltage of the op-amp but also effectively reduce the detection error, which is caused by circuit noise and leakage current. Measurements of the implemented peak detector show that in the case that the detection signal frequency is 20 kHz and the amplitude is 10 mV, the detection error is decreased to 30 µV with the equivalent output noise of 71 n V / H z . [ABSTRACT FROM AUTHOR]

This paper presents a proposed capacitance readout circuit that enables a quadrupled (x4) output strength. A symmetric cross-coupling structure is proposed to amplify the voltage difference between two adjacent channels; hence, the detected signal can be integrated twice every clock cycle. Compared with conventional schematics, the proposed readout circuit shows an increased output strength for integration times within dozens of μs. In addition, the measurements show that the integrator resistors should be less than 1 kΩ to suppress the resistance–capacitance delay effects. Although the proposed capacitance readout circuit is implemented using discrete transistors, it has a good signal integrity at an operating clock cycle of 100 µs. Therefore, the proposed readout circuit is a promising way to detect small capacitance variations with short integration times. [ABSTRACT FROM AUTHOR]

Though impressive advances of the extension of effective working distance for magnetic resonant coupling wireless power transfer system have been made over past decades, their applications have been severely limited by the requirement of unidirectional coaxial distribution for the transmitter and receiver. In this paper, an omnidirectional magnetic resonant coupling wireless power transfer system is proposed. The cubic spiral transmitter requires only a single power source, and the receiver receives power in all directions. The power transfer efficiency of the system is derived through an equivalent circuit model. And an impedance matching circuit which includes a pair of parallel and series capacitors is proposed for better stability and higher efficiency. In addition, geometrical parameters of the single power driven spiral transmitter structure are optimized to improve distribution uniformity for different directions. Thus the power transfer efficiency of the system, which depends on the distance between the transmitter and the receiver, is almost the same for different receiving angles. Finally, the theoretical analysis is verified by practical experimental results, which shows the power transfer efficiency of 60% at 150 mm. [ABSTRACT FROM AUTHOR]

The microwave dielectric behavior of sandwich-like Ti3C2 MXene nanosheets with efficient microwave absorption was investigated by a combination of experiments and simulations. The obvious frequency dispersion effect and the double-peaked feature of dielectric spectra in Ti3C2 MXene nanosheets could be observed over the frequency range of 2–18 GHz, giving rise to superior microwave attenuation capability. Furthermore, a revised Drude-Lorentz model was proposed to explain the peaked feature of permittivity, and simulated results were demonstrated to agree well with the experimental measurements. It was concluded that the hopping migration between Ti3C2 MXene nanosheets with longer relaxation time than “micro-dipole” relaxation within nanosheets makes a superior contribution to overall absorbing performance. [ABSTRACT FROM AUTHOR]