CN-121983099-A - Multi-value RRAM read-write circuit and read-write method thereof

CN121983099ACN 121983099 ACN121983099 ACN 121983099ACN-121983099-A

Abstract

The invention belongs to the technical field of analog integrated circuits and storages, and relates to a multi-value RRAM read-write circuit and a read-write method thereof, wherein the multi-value RRAM read-write circuit comprises a RRAM control unit, a low dropout linear voltage regulator, a standard resistance unit, a leakage current sampling unit, a read-write conversion unit, a CMOS switch and an operational amplifier, the low dropout linear voltage regulator is used for providing stable grid voltage for the RRAM control unit and the standard resistance unit, the standard resistance unit is used for adjusting the resistance value of the RRAM, the leakage current sampling unit is used for sampling and compensating leakage current, the read-write conversion unit receives a read-write conversion signal, the CMOS switch is controlled based on the read-write conversion signal to switch the read mode or the write mode of the multi-value RRAM read-write circuit, and the operational amplifier is connected in the write mode and used for maintaining the voltage stability at two ends of the RRAM. The invention can sample and compensate leakage current, and greatly reduce the influence of the leakage current on RRAM reading and writing.

Inventors

LIU ZICHENG
WANG HAITAO
YANG YIMING
HU TINGTING
LIU YONGCHEN

Assignees

重庆北理芯研科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260407

Claims (9)

1. A multi-value RRAM read-write circuit is characterized by comprising an RRAM control unit, a low dropout linear voltage regulator, a standard resistance unit, a leakage current sampling unit, a read-write conversion unit, a CMOS switch and an operational amplifier; the low dropout linear regulator is connected with the RRAM control unit and the standard resistance unit and is used for providing stable grid voltage for the RRAM control unit and the standard resistance unit; The RRAM control unit comprises an RRAM and a control circuit, and the standard resistance unit is used for adjusting the resistance value of the RRAM; The current sampling unit is connected with the RRAM control unit and the standard resistor unit and is used for sampling and compensating leakage current, receives a state control signal and a current mirror control signal, has a sampling state and a compensation state, and is in the sampling state when the state control signal is in a high potential and the current mirror control signal is in a low potential so as to sample the leakage current; The read-write conversion unit is connected with the CMOS switch and is used for receiving the read-write conversion signal, and controlling the on-off state or the on-state of the CMOS switch based on the read-write conversion signal so as to switch the read mode or the write mode of the multi-value RRAM read-write circuit; The operational amplifier is connected to the RRAM control unit in a writing mode and used for maintaining voltage stability at two ends of the RRAM.
2. The multivalue RRAM read/write circuit of claim 1, wherein the leakage current sampling unit includes a CMOS switch group, a state transition circuit, a current mirror, and a current mirror state control circuit; The state switching circuit is connected with the CMOS switch group and used for controlling the on/off of the switches in the CMOS switch group, the CMOS switch group comprises four switches, two of the four switches are used for changing the working state of the transistors in the current mirror, the other two of the four switches are used for changing the feedback path of the low-dropout linear voltage regulator, the current mirror state control circuit is connected with the current mirror and used for controlling the current mirror to be in a diode state or a current mirror state, when the current mirror is in the diode state, the leakage current sampling unit enters a sampling state, and when the current mirror is in the current mirror state, the leakage current sampling unit enters a compensation state.
3. The multi-value RRAM read-write circuit of claim 2, wherein the feedback path of the low dropout linear regulator is changed by feeding back the voltage across the RRAM to the low dropout linear regulator in a sampling state to maintain the voltage across the RRAM stable to sample the current across the RRAM at a certain voltage, and feeding back the voltage across the standard resistor unit to the low dropout linear regulator in a compensation state to maintain the voltage across the standard resistor unit stable to allow the current across the RRAM to be fully controlled.
4. The multi-value RRAM read-write circuit of claim 2, further comprising a write verification unit, wherein when the leakage current sampling unit is in the compensation state, the multi-value RRAM read-write circuit enters a read-write mode, and the read mode and the write mode are switched based on a read-write switching signal, and the multi-value RRAM read-write circuit specifically comprises: When the read-write conversion signal is in a high potential, the multi-value RRAM read-write circuit enters a write mode, the read-write conversion unit controls the CMOS switch to be switched on, and the operational amplifier and the write verification unit are simultaneously connected into the multi-value RRAM read-write circuit so as to maintain the voltage stability at two ends of the RRAM and monitor the write state, and after the write is finished, the state control signal is pulled to the high potential; When the read-write conversion signal is in low potential, the multi-value RRAM read-write circuit enters a read mode, the read-write conversion unit controls the CMOS switch to be disconnected, the operation amplifier and the write verification unit are disconnected from the multi-value RRAM read-write circuit, voltages at two ends of the RRAM are directly read, and the state control signal is pulled to high potential after the reading is completed.
5. The multi-value RRAM read/write circuit of claim 1, wherein the standard resistor unit includes a plurality of parallel standard resistors, the current in the RRAM is a mirror image of the current in the standard resistor unit, so that the resistance of the RRAM is the total resistance of the parallel standard resistors, the number of parallel standard resistors is equal to the data width required to be written into the RRAM, each parallel standard resistor has two states of on and off, and the total resistance of the parallel standard resistor is changed by controlling the on or off of each standard resistor, so as to adjust the resistance of the RRAM, thereby realizing multi-value writing.
6. A reading and writing method of a multi-value RRAM reading and writing circuit, based on the multi-value RRAM reading and writing circuit implementation of any one of claims 1 to 5, characterized by comprising: S1, initializing a multi-value RRAM read-write circuit, and providing stable grid voltage for an RRAM control unit and a standard resistor unit; S2, setting a state control signal to be high potential and setting a current mirror control signal to be low potential, so that a leakage current sampling unit is in a sampling state, and sampling leakage current; s3, setting the state control signal and the current mirror control signal to be low potential, so that the leakage current sampling unit is in a compensation state, and generating compensation current to counteract leakage current; S4, adjusting the potential of the read-write conversion signal to control the multi-value RRAM read-write circuit to enter a write mode or a read mode; S5, after the writing operation or the reading operation is completed, the state control signal is pulled back to the high potential.
7. The method for reading and writing a multi-valued RRAM read-write circuit of claim 6, wherein the compensation current is generated by: and recording the gate voltage when the leakage current sampling unit is in a sampling state, and driving a current mirror included in the leakage current sampling unit based on the recorded gate voltage when the leakage current sampling unit is in a compensation state to generate compensation current.
8. The method for reading and writing a multi-valued RRAM read-write circuit of claim 6, wherein S4 specifically includes: the read-write conversion signal is adjusted to be high potential, the multi-value RRAM read-write circuit enters a write mode, voltage stability at two ends of the RRAM is maintained based on an operational amplifier, and the write state is monitored based on a write-in verification unit; and adjusting the read-write conversion signal to be low potential, and enabling the multi-value RRAM read-write circuit to enter a read mode to directly read the voltages at two ends of the RRAM.
9. The method according to claim 8, wherein after entering the write mode, controlling the on/off of each standard resistor changes the total resistance of the parallel standard resistors in the standard resistor unit to adjust the resistance of the RRAM, thereby realizing the multi-value writing.

Description

Multi-value RRAM read-write circuit and read-write method thereof Technical Field The invention relates to the technical field of analog integrated circuits and storages, in particular to a multi-value RRAM read-write circuit and a read-write method thereof. Background Resistive random access memory (RESISTIVE RANDOM ACCESS MEMORY, RRAM) is an emerging memory in which information is stored in the resistance of memory cells, which are typically composed of very thin dielectric layers on the nanometer scale, the material of which is typically an insulator. By forcing a current through the dielectric layer, small conductive filaments consisting of ionic vacancies (as well as positive charges) are formed in the dielectric material, resulting in a change in resistance. By applying current in the opposite direction, the filaments may break, resulting in an increase in resistance. The difference in resistance between the formed and ruptured filaments can be interpreted as a different cell state and used as memory, and the stored data is nonvolatile and will not be lost after power failure. The multi-value read-write of the RRAM means that more than 1 bit of information is stored in one memory cell by precisely controlling the resistance state of the resistive switching layer. The multi-value read-write RRAM can improve the storage density of data, reduce the operation energy consumption of each bit of data and naturally adapt to the analog calculation (such as weight mapping) of a neural network, and is a key technology for improving the RRAM storage density and reducing the cost. The current leakage current exists in the RRAM array and can have the following effects on the read-write of the RRAM, namely, firstly, the current leakage can form shunt through the low-resistance paths when the target unit is in a high-resistance state and surrounding unselected units are in a low-resistance state, so that the actual read current is far greater than the actual current of the target unit. The system may erroneously recognize a high resistance state as a low resistance state, the system may erroneously write, if the voltage received by an unselected cell exceeds its threshold value when writing a certain row or column, the unselected cell may also be accidentally set or reset, causing ‌ data to be accidentally modified, the read/write margin may be reduced, the leakage current may interfere with the current signal of the target cell, the current difference between the high resistance state and the low resistance state (i.e., the read margin) may be reduced, the signal-to-noise ratio may be reduced, the sense amplifier may be difficult to accurately determine the state, the power consumption may be increased, the leakage current may continuously flow in the unselected path, causing additional static power consumption, especially the cumulative effect in a large-scale array may be significant ‌, the fifth may cause write failure or require multiple verifications, the leakage current may disturb the programming accuracy in an analog memory integrated application, the write value may deviate from the target, the "write-verify" operation may need to be repeatedly performed, the delay may be increased, and the energy efficiency may be reduced ‌. In view of this, it is desirable to provide a multi-value RRAM read/write circuit and read/write method capable of reducing the influence of leakage current on RRAM read/write. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a multi-value RRAM read-write circuit and a read-write method thereof, wherein a leakage current sampling unit is adopted for sampling and compensating leakage current, so that the influence of the leakage current on RRAM read-write is greatly weakened, only one operational amplifier and a low-dropout linear voltage stabilizer are used in the whole circuit, the read-write mode is switched by adjusting a CMOS switch, the read-write function is achieved, a large area is not occupied, and the low-dropout linear voltage stabilizer provides stable voltage for the whole circuit, so that the influence of voltage fluctuation is effectively restrained. In addition, the resistance value of the RRAM is adjusted by setting the reference resistor and the mirror current, so that the process of adjusting the resistance value in a feedback way is avoided, and the writing speed is improved. In order to achieve the above purpose, the invention adopts the following technical scheme: In a first aspect, the invention provides a multi-value RRAM read-write circuit, which comprises an RRAM control unit, a low dropout linear voltage regulator, a standard resistance unit, a leakage current sampling unit, a read-write conversion unit, a CMOS switch and an operational amplifier; the low dropout linear regulator is connected with the RRAM control unit and the standard resistance unit and is used for providing stable grid voltage for the RRAM control unit