Hybrid self-tracking reference circuit for rram cells
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsZheng-Jun Lin, Chung-Cheng Chou, Yu-Der Chih, Pei-Ling Tseng
Life of this patent
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Abstract
The disclosed invention presents a self-tracking reference circuit that compensates for IR drops and achieves the target resistance state at different temperatures after write operations. The disclosed self-tracking reference circuit includes a replica access path, a configurable resistor network, a replica selector mini-array and a step current generator that track PVT variations to provide a PVT tracking level for RRAM verify operation.
Claims21
A current reference circuit for a resistive random-access memory (RRAM) cell, comprising:
- a configurable resistor network, wherein the configurable resistor network is configured to emulate a resistive element of the RRAM cell;
- a replica access path, wherein the replica access path is connected to a first terminal of the configurable resistor network and wherein the replica access path emulates an access path associated with the RRAM cell;
- a replica selector circuit connected to a second terminal of the configurable resistor network and wherein the replica selector circuit emulates a selector circuit associated with the RRAM cell;
- a step current generator circuit connected to the configurable resistor network, wherein the step current generator is used to adjust the reference current level provided by the current reference circuit;
- and
- wherein the replica access path, the configurable resistor network, the replica selector circuit and the step current generator circuit are configured to track of process, voltage and temperature (PVT) variations.
A system comprising:
- a resistive random-access memory (RRAM) device wherein the RRAM device includes:
- a RRAM cell;
- a first terminal of an access path connected to a first terminal of the RRAM cell;
- and
- a selector circuit connected to a second terminal of the RRAM cell;
- a current reference circuit, wherein the current reference circuit includes:
- a configurable resistor network, wherein the configurable resistor network is configured to emulate a resistive element of the RRAM cell;
- a replica access path, wherein a first terminal of the replica access path is connected to a first terminal of the configurable resistor network and wherein the replica access path emulates the access path associated with the RRAM cell;
- and
- a replica selector circuit connected to a second terminal of the configurable resistor network and wherein the replica selector circuit emulates the selector circuit associated with the RRAM cell;
- and
- a sense amplifier circuit including two input terminals, wherein a second terminal of the access path is connected to one input terminal of the sense amplifier circuit and a second terminal of the replica access path is connected to another input terminal of the sense amplifier circuit.
A method, comprising:
- selectively connecting one of a first RRAM device or a second RRAM device to a first input of a sense amplifier, wherein the each of the first and second RRAM devices include a RRAM cell;
- configuring a reference circuit to emulate the selected first or second RRAM device;
- generating a reference current by the reference circuit that tracks process, voltage and temperature (PVT) variations;
- selectively connecting the reference circuit to a second input of the sense amplifier;
- and
- comparing a current value of the selected first or second RRAM device with reference current by the sense amplifier to read data from the first or second RRAM cell.
Dependencies are inferred from the claim text.