A positive correlation between set voltage, V-set, and the preceding reset voltage, vertical bar V-reset vertical bar, has been observed in resistive RRAM memory arrays and explained in terms of mechanisms responsible for forming and rupturing of the conductive Cu filament. This correlation can be reproduced on a single device by generating a spread in V-reset values by varying the linear voltage ramp rate. The dependence of V-reset on voltage ramp rate can be modeled by assuming that critical Joules heat is needed to trigger the rupture of the filament. Mechanisms are proposed to explain why higher vertical bar V-reset vertical bar necessarily leads to a higher V-set value during a subsequent set operation. The resulting dependence of V-set and V-reset on the voltage ramp rate during the reset operation can be used to tighten V-set and V-reset distributions, by applying low voltage ramp rates to cells with high V-set and high ramp rates to cells with low V-set values. (C) 2015 Elsevier B.V. All rights reserved.