Electronically Tunable Emulation Circuit for TiO2 Memristor with Its Illustrative Applications

The fourth fundamental passive circuit element i.e., the Memristor, since its inception has been associated with several promising applications. However, memristor-based circuit design has not been able to take off as expected because of the non-availability of actual memristive devices. Researchers have therefore looked forward to memristor-emulator circuits to carry out the design of memristor applications. This paper is one such attempt to present a tunable memristor emulator circuit using other CMOS integrated circuits. The proposed memristor emulator mimics the signature characteristics of the nanoscale TiO2 memristor. By virtue of the use of a CMOS building block known as Current Controlled Differential Difference Current Conveyor (CCDDCC), the proposed circuit is able to use to its advantage a parasitic resistance available at one of the input ports of the CCDDCC. This facilitates a reduction in the number of passive components besides providing an additional feature of electronic tunability of the obtained memristance. Extensive SPICE simulations along with a breadboard experiment have been performed to validate the theoretical analysis. Besides the routine V-I characteristics plots, non-ideal and Monte-Carlo analyses have also been performed to demonstrate the robustness of the circuit. Additionally, the behavior of memristor for the variations in capacitance, frequency, temperature and supply voltage has been analyzed. Once the correct working of the proposed memristor emulator is established, the paper goes on to provide two illustrative application examples. Firstly, it is shown that the proposed memristor emulator can be used as a controlled synaptic weight in neuromorphic circuits. Secondly, a simple first-order passive high-pass filter using the proposed memristor emulator is presented, which although simplistic, goes on to highlight the advantages of the proposed circuit.