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An equivalent circuit representation for the conduction characteristics of TiO 2 -based resistive switches based on the generalized diode equation is reported. The proposed model consists of two antiparallel diodes with series and parallel resistances representing the filamentary current pathway spanning the oxide layer and the possible parasitic conduction effects. The model accounts for the pulse-induced hysteretic behavior exhibited by the I-V characteristic after electroforming. Three different approaches, each one of them with increased complexity, are assessed: 1) constant; 2) nanowire-like; and 3) sigmoidal diode amplitude. In all cases, the logarithmic conductance of the diodes is modeled using a logistic-type threshold function.

Filamentary conduction in resistive switching metalinsulator-metal (MIM) devices is often modeled from the circuital viewpoint using diode-like structures with series resistances. We show in this Research Letter which arrangement of diodes and resistances is compatible with experimental multilevel set and reset I-V characteristics in electroformed TiN/SiO x /TiN structures. The proposed model is based on the solution of the generalized diode equation corresponding to N diodes arranged in parallel with a single series resistance. The model is simple yet accurate and it is able to capture the essential features exhibited by the I-V curves in the low and high bias regimes, revealing that a single equation can deal with both the low and high resistancestates. An exact expression for the differential conductance suitable for small-signal analysis and circuit simulators is also provided.

The hysteresis current-voltage (I-V) loops in Pt/BiFeO3/SrRuO3 structures are simulated using a Schottky diode-like conduction model with sigmoidally varying parameters, including series resistance correction and barrier lowering. The evolution of the system is represented by a vector in a 3D parameter space describing a closed trajectory with stationary states. It is shown that the hysteretic behavior is not only the result of a Schottky barrier height (SBH) variation arising from the BiFeO3 polarization reversal but also a consequence of the potential drop distribution across the device. The SBH modulation is found to be remarkably lower (<0.07 eV) than previously reported (>0.5 eV). It is also shown that the p-type semiconducting nature of BiFeO3 can explain the large ideality factors (>6) required to simulate the I-V curves as well as the highly asymmetric set and reset voltages (4.7 V and −1.9 V) exhibited by our devices.

Soil Moisure and Ocean Salinity (SMOS) was the first ESA satellite relying on a complete optical harness, which was initially selected for the mechanical properties of optical fibre, what facilitated the deployment of the 3 arms of the instrument. In addition, other interesting advantages of the optical harness, as immunity to electromagnetic interference, high bandwidth, low losses and mass, etc., played an important role in the instrument performance.In the frame of the the ESA ITI contract No 4000120740/17/NL/AI, based on the advantages of optical cables and the good results obtained in SMOS mission, DAS team along with Airbus DS is studying different optical harness configurations as an evolution towards a full optical harness system for a future SMOS Operational (SMOS-OPS) Lband radiometer. In particular, different Optical Harness (OHA) configurations have been studied in order to select the two most promising options.The first configuration aims at solving some identified issues as well as at improving performance of SMOS thanks to lessons learnt from the in-orbit operation, but without attempting novel techniques of calibration or signal distribution.The second configuration explores the application of alternative techniques like the use of WDM or multi-RF over fibre. The main goals of this second configuration are the improvement of the electrical performance and the optimization of the optical harness in terms of layout, i.e, to reduce number of cables/fibres, size, weight, as well as power consumption.