A Versatile, Voltage-Pulse Based Read and Programming Circuit for Multi-Level RRAM Cells

In this work, we present an integrated read and programming circuit for Resistive Random Access Memory (RRAM) cells. Since there are a lot of different RRAM technologies in research and the process variations of this new memory technology often spread over a wide range of electrical properties, the proposed circuit focuses on versatility in order to be adaptable to different cell properties. The circuit is suitable for both read and programming operations based on voltage pulses of flexible length and height. The implemented read method is based on evaluating the voltage drop over a measurement resistor and can distinguish up to eight different states, which are coded in binary, thereby realizing a digitization of the analog memory value. The circuit was fabricated in the 130 nm CMOS process line of IHP. The simulations were done using a physics-based, multi-level RRAM model. The measurement results prove the functionality of the read circuit and the programming system and demonstrate that the read system can distinguish up to eight different states with an overall resistance ratio of 7.9.

Automated summary

An integrated read and programming circuit for RRAM cells with versatility in adapting to different cell properties was presented. The circuit is suitable for read and programming operations based on voltage pulses, and can distinguish up to eight different states, achieving digitization of analog memory values. The functionality of the circuit and system was proven through measurement results, with the ability to distinguish up to eight different states and an overall resistance ratio of 7.9.