About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
A-SSCC 2014
Conference paper
A 6-bit drift-resilient readout scheme for multi-level phase-change memory
Abstract
Multiple-Level Cell (MLC) storage provides increased capacity and hence reduced cost-per-bit in memory technologies, thereby rendering such technologies suitable for big data applications. In Phase-Change Memory (PCM), however, MLC storage is seriously hampered by the phenomenon of resistance drift. We present a readout circuit for PCM specifically designed for drift resilience in MLC operation. Drift resilience is achieved through the use of specific non-resistance-based cell-state metrics which, in contrast to the traditional cell-state metric, i.e., the low-field electrical resistance, have built-in drift robustness. The circuit provides a fast and efficient implementation of drift-resilient metric, enabling, for the first time, the performance required by non volatile memory applications. In addition, by exploiting the non linear sub-threshold I-V characteristics of PCM cells, the readout architecture promises to increase the distinguishable signal range. The proposed read circuitry is designed and fabricated in 64-nm CMOS technology. Experimental results using an integrated test resistor array for readout circuit characterization are presented, demonstrating access time of 450 ns at 6-bit raw (5-bit effective) resolution. The circuit has low-noise characteristics and does not exhibit sensitivity to bit-line parasitics. The readout circuit is co-integrated with a 16 Mb 2x-nm PCM cell array and the necessary programming electronics.