A bridge technique for memristor state programming

Abstract

ABSTRACTIn order to effectively use a memristor in analog circuits, its memristance should be adjusted to a desired value between its limits. Since the maximum and minimum required memristance typically varies considerably between different types of memristors, it is almost impossible to tune the resistance of each memristor based on a reference resistor. Which is mostly done using some programmer circuits. Moreover, those programming strategies involving pulses are time-consuming and they impose high hardware headroom. In this paper, a novel CMOS circuit is presented for programming memristors. A Wheatstone bridge circuit is used to measure the current memristance, while the programming current is flowing through the device. Using such an approach reading the state and its adjustment are done simultaneously, which reduces the programming latency. In the proposed method, instead of tuning the memristance, the state of the memristor will be set to the desired value, which is proportional to a control voltage. The low programming latency, six-bit accuracy, and use of a simple circuit for programming, are the main advantages of our solution. The proposed circuit is designed and laid out in 0.35 µm CMOS technology and takes 0.0273mm2. Furthermore, the proposed approach is applied to a memristor emulator to demonstrate its correct operation in real applications.