Analysis of resistance variations and variance-aware read circuit for cross-point ReRAM

An adaptive reference control is proposed to adjust the reference current of current-mode sense amplifier (SA) for optimum read margin along with spatial distribution and temporal drift of the resistance of ReRAM cells. An ADC-based SA for distributed dummy cell is used to examine the distribution data, and binary SA with regulated reference for memory cells provides fast and reliable read in cross-point cell array. The adaptive reference control prevents yield drop due to resistance degradation after 10⁶ times read disturbance. Maximum read speed of disturbed ReRAM is also improved from 50ns to 28.4ns. The circuit is fabricated using 350nm CMOS technology and mounted with 1-Kb HfOx cross-point array to verify the control.