Low Voltage Programming of RRAM-based Crossbar Arrays using MOS Parasitic Diodes

Sachin Maheshwari^*Alexantrou SerbThemis Prodromakis

• School of Engineering, University of Edinburgh, Edinburgh, Scotland, United Kingdom

The 1-Transistor-1-Resistor (1T1R) RRAM-based crossbars have been exploited mainly due to their high density, scalability, and low-power properties. However, the series resistance of the transistor is a major problem in 1T1R crossbar arrays. This limits the maximum current available for inducing resistive switching and degrades the array's performance. To mitigate this issue, we proposed a new configuration, 1-Transistor-1-Diode-1-Resistor (1T1D1R), in which we use diodes (including the bulk-source/drain parasitic diodes of the access transistor) to bypass the gating transistor during the programming operation ('write'). The proposed solution trades increased overhead in the layout area with a dramatic increase in the maximum achievable current drive on RRAM devices, resulting in the ability to deliver 1.5mA+ with a voltage supply of as low as 1.2V using minimum size devices (in our implementation). We designed a 32×32 crossbar array with on-chip peripheral circuitry in commercially available 0.18µm triple-well cmos technology for the proof of concept. We demonstrated bidirectional programming, showing a memristance change of ≈ 500Ω for 120 and 80 pulses in positive and negative directions.