Narrow Results

Many researchers have focused on molecular electronics, and this field can progress faster by applying semiconductors to molecular modeling. In this work, two middle rings of a bipyridine–biborinine molecular diode are rotated from 25^∘ to 90^∘ such that the current along the molecule is reduced. The current is minimum and almost zero at 90^∘, while it is maximum at 25^∘. Accordingly, considering these two angles, the molecule can act as a switching device when the two middle rings are rotated. The bipyridine–biborinine molecular diode is modeled considering the effect of rotation by including two resistors in the model. Two parallel diodes are used in this modeling for pyridine and borinine rings. The ideality factors of these diodes are varied based on the electronegativity of pyridine and borinine rings. This model is then applied to consider different molecular logic gates such as NAND, NOR, NOT, OR and AND gates, as well as molecular logic circuits (half adder and full adder), using the unique capabilities of the LTspice software.

In this paper, a current-mode (CM) proportional integral derivative (PID) controller based on second-generation voltage conveyor (VCII) is presented. The proposed circuit consists of two-plus type VCIIs, two resistors, and two capacitors. There is no need of critical matching condition. Considering the parasitic impedance, the operating frequency ranges of the proposed PID network are examined. The magnitude and phase responses, Monte Carlo, temperature and input-output noise analyses have been simulated. The simulation results are obtained with the LTspice program using AD844 SPICE macro-model under $\pm$9V DC supply voltages. The total power consumption of the proposed CM PID controller is 235mW.

We develop a tri-state memristive system based on composable binarized memristors, from both a dynamical systems construction to the development of in-house fabricated devices. Firstly, based on the SPICE model of the binary memristor, the series and parallel circuits of binary memristors are designed, and the characteristics of each circuit are analyzed in detail. Secondly, through the analysis of the connection direction and parameters of the two binary memristors, an effective method to construct a tri-state memristor is proposed, and verified using SPICE simulations. Finally, the characteristics of the constructed equivalent tri-state memristor are analyzed, and it is concluded that the amplitude, frequency and type of the input signal can affect the characteristics of the equivalent tri-state memristor. Predictions from this modeling were validated experimentally using Au/${\mathrm{\text{Nb}}}_2{\mathrm{\text{O}}}_5$/Nb cross-point devices.