Patent ID: 9666273
Date: 2017-05-30
CPC Classifications: G11C

Claim:
1. A device for determining an actual cell state of a resistive memory cell having a plurality M of programmable cell states, the device comprising: a sensing circuit configured to sense a sensing voltage of the resistive memory cell and to output a resultant value in response to the sensing voltage which is indicative for the actual cell state, a settling circuit, including a plurality of current mirrors, configured to settle the sensing voltage to a certain target voltage representing one of the M programmable cell states, a prebiasing circuit configured to pre-bias a bitline capacitance of the resistive memory cell such that the sensing voltage is close to the certain target voltage, and a resistance circuit including a plurality of resistors connected in series and coupled in parallel to the resistive memory cell, wherein the resistance circuit is configured to reduce an effective resistance seen by the prebiasing circuit, wherein the settling circuit and the resistance circuit are configured to form a plurality of current-resistor pairs being switchable to define a linear range of detection currents corresponding to the certain target voltages, each of the plurality of current-resistor pairs including one current mirror and one resistor; wherein the plurality of resistors are coupled in series to each other and wherein the plurality of current mirrors are coupled in parallel to each other; further comprising a comparing circuit configured to provide a comparison result by comparing the sensing voltage and a reference voltage; wherein the comparing circuit includes a plurality of voltage comparators; wherein the number of voltage comparators corresponds to the number of current-resistor pairs; wherein each of the plurality of voltage comparators is allocated to one current-resistor pair; wherein each of the voltage comparators provides a comparison result and wherein each comparison result is usable as a control signal for controlling switching of a corresponding current-resistor pair; and wherein the settling circuit includes a plurality of switches, each of which is coupled in series to one of the current mirrors and is configured to receive the control signal and to deactivate the corresponding current mirror by opening the switch or to activate the corresponding current mirror by closing the switch.