Low power read operation for programmable resistive memories

• US 10,535,413 B2
• Filed: 04/14/2018
• Issued: 01/14/2020
• Est. Priority Date: 04/14/2017
• Status: Active Grant

• Current Assignee: Attopsemi Technology Co., Ltd.
• Original Assignee: Attopsemi Technology Co., Ltd.
• Inventors: Chung, Shine C.
• Primary Examiner(s): Tran, Michael T
• Application Number:
  US15/953,422
• Publication Number:
  US 20180301198A1
• Time in Patent Office: 640 Days
• Field of Search: 365 96, 365158
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/2273 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 16/0408 comprising cells containing floating gate transistors G11C16/0483, G11C16/0491 take precedence
• CPC Class Codes: G11C 16/28 using differential sensing or reference cells, e.g. dummy cells
• CPC Class Codes: G11C 17/165 Memory cells which are electrically programmed to cause a change in resistance, e.g. to permit multiple resistance steps to be programmed rather than conduct to or from non-conduct change of fuses and antifuses digital stores using resistance random access memory elements G11C13/0002
• CPC Class Codes: G11C 17/18 Auxiliary circuits, e.g. for writing into memory

Abstract

A programmable resistive memory has a plurality of programmable resistive devices (PRD) and at least one sensing circuit. The at least one of the programmable resistive device can include at least one programmable resistive element (PRE). The sensing circuit can include one PRD unit and a reference unit. Each unit has at least one capacitor to charge to a second supply voltage line and to discharge to the first supply voltage line through the PRE and the reference element, respectively. The capacitors are also coupled to comparators to monitor discharging voltages with respect to a reference voltage. By comparing the time difference when the comparators change their outputs, the magnitude of the PRE resistance with respect to the reference element resistance can be determined and converted into logic states.

Claims

1. A programmable resistive memory, comprises:

a primary cell including at least;

a selector controlled by a control signal, the selector having a first end and a second end, the second end being coupled to a first conductive line;

a capacitor selectively coupled to a second conductive line; and

a programmable resistive element (PRE) having a first end able to be coupled to the capacitor and a second end coupled to the first end of the selector; and

a reference cell including at least;

a reference selector controlled by the control signal, the reference selector having a first end and a second end, the second end being coupled to the first conductive line;

a reference capacitor selectively coupled to the second conductive line; and

a reference resistance element having a first end able to be coupled to the reference capacitor and a second end coupled to the first end of the reference selector,

wherein a discharge time of the PRE relative to a discharge time of the reference resistance element is used to determine resistance of the PRE.

2. A programmable resistive memory as recited in claim 1, wherein the programmable resistive memory comprises:

a primary logic device able to be coupled to the first end of the PRE and operable to provide a primary logic state of the primary cell, and

a reference logic device able to be coupled to the first end of the reference resistance element and operable to provide a reference logic state of the reference cell.

3. A programmable resistive memory as recited in claim 2, wherein the programmable resistive memory includes at least one reference cell and a plurality of programmable resistive device (PRD) cells, each of the PRD cells including the primary cell, and

wherein the programmable resistive memory comprises:

an output logic device to output a logic state of the at least one of the PRD cells, the output logic device being coupled to the primary logic device and the reference logic device.

4. A programmable resistive memory as recited in claim 1, wherein the programmable resistive element comprises one-time programmable (OTP) element in OTP memory, magnetic tunnel junction (MTJ) in an MRAM or RRAM element in an RRAM.

7. A programmable resistive memory as recited in claim 1, wherein the programmable resistive memory comprises:

a primary switch coupled to the first end of the PRE, and

a reference switch coupled to the first end of the reference resistance element.

5. A programmable resistive memory, comprises:

a plurality of programmable resistive device (PRD) cells; and

a time-based sensing circuit including at least;

a selector controlled by a control signal, the selector having a first end and a second end, the second end being coupled to a first conductive line;

a capacitor selectively coupled to a second conductive line;

a programmable resistive element (PRE) having a first end coupled to the capacitor and a second end coupled to the first end of the selector; and

a comparator coupled to the first end of the PRE,

wherein the time-based sensing circuit using different discharge time to determine resistance of the PRE,

wherein the programmable resistive element is an one-time programmable (OTP) element that comprises at least one of an anti-fuse, fuse or floating-gate device.

6. A programmable resistive memory, comprises:

a plurality of programmable resistive device (PRD) cells; and

a time-based sensing circuit including at least;

a selector controlled by a control signal, the selector having a first end and a second end, the second end being coupled to a first conductive line;

a capacitor selectively coupled to a second conductive line;

a programmable resistive element (PRE) having a first end coupled to the capacitor and a second end coupled to the first end of the selector; and

a comparator coupled to the first end of the PRE,

wherein the time-based sensing circuit using different discharge times to determine resistance of the PRE,

wherein the programmable resistive element comprises at least one of RRAM or MRAM device.

8. An electronic system, comprises:

a processor; and

a programmable resistive memory operatively connected to the processor, the programmable resistive memory includes at least a plurality of programmable resistive device (PRD) cells for providing data storage, each of the programmable resistive device cells comprising;

a programmable resistive element (PRE) coupled to a first supply voltage line through a selector with an enable signal; and

a time-base sensing circuit coupled to at least one PRD cell unit and a reference unit having a PRE and a reference resistor, respectively;

each of the PRD cell unit and the reference unit are coupled to capacitors that can be charged to a second supply voltage line and discharged through the PRE and the reference resistor, respectively, to the first supply voltage line;

the PRD cell unit and the reference unit are coupled to at least one comparator to change output logic state when the voltages are discharged to a reference voltage,

wherein the capacitors in both units are charged to the second supply voltage approximately and discharged to the first supply voltage line by turning on the enable signal at the same time, and

wherein the PRE resistance can be converted into logic state based on different discharge rates by the PRD cell unit and the reference unit.

9. An electronic system as recited in claim 8, wherein the comparator outputs of the cell and reference units are coupled to latches or flip-flops, respectively, and an output of the latch or flip-flop depends on whether the PRE resistance is larger or smaller than the reference resistance.

10. An electronic system as recited in claim 8, wherein the reference voltage for the comparator is approximately half way between the first and the second supply voltages.

11. An electronic system as recited in claim 8, wherein the programmable resistive element comprises at least one of floating-gate device, electrical-fuse, phase-change film in PCRAM, resistive film in RRAM, ferroelectric film in FeRAM, or magnetic tunnel junction in MRAM.

12. An electronic system as recited in claim 8, wherein the programmable resistive element comprises at least one of polysilicon, silicided polysilicon, silicide, metal, metal alloy, thermal isolated active region, trench silicide in FinFET, FinFET itself, or MOS gate.

13. An electronic system as recited in claim 8, wherein the programmable resistive element is an anti-fuse fabricated by a single or plural of contacts or vias with dielectrics in between, or an anti-fuse comprising of a CMOS gate and a CMOS body with gate oxide in between.

14. An electronic system as recited in claim 8, wherein the comparator is an inverter.

15. A method for providing a programmable resistive memory, comprising:

providing a plurality of programmable resistive device cells, at least one of the programmable resistive device cells include at least (i) a programmable resistive element coupled to a first supply voltage line through a selector with an enable signal; and

(ii) a time-base sensing circuit coupled to at least one PRD cell unit and a reference unit having a PRE and a reference resistor, respectively;

the PRD cell unit and the reference unit are coupled to at least one capacitor that can be charged to a second supply voltage line and discharged through the PRE and the reference resistor, respectively, to the first supply voltage line;

the PRD cell and the reference unit are coupled to at least one comparator, and wherein the comparator changes output logic states based on a comparison of the voltage discharged to a reference voltage;

turning on the enable signal of the PRD unit and reference unit, after the capacitors are charged to the second supply voltage approximately, to discharge the capacitors through the PRE and reference element respectively; and

converting the PRE resistance into logic states by the time difference of the comparator output changes.

16. A method as recited in claim 15, wherein the programmable resistive device cells are one-time programmable memory cells.

17. A method as recited in claim 16, wherein a discharge rate is dependent on capacitance of the capacitor and the resistance value.

18. A method as recited in claim 17, wherein the programmable resistive element comprises at least one MRAM device.

19. A method as recited in claim 17, wherein the programmable resistive element comprises at least one RRAM.