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Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes

Qiao Wang1, 2, Donglin Zhang1, 2, Yulin Zhao1, 2, Chao Liu1, Xiaoxin Xu1, 2, Jianguo Yang1, 3, and Hangbing Lv1, 2

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 Corresponding author: Jianguo Yang, yangjianguo@ime.ac.cn

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Abstract: In this work, two process-variation-tolerant schemes for a current-mode sense amplifier (CSA) of RRAM were proposed: (1) hybrid read reference generator (HRRG) that tracks process-voltage-temperature (PVT) variations and solve the nonlinear issue of the RRAM cells; (2) a two-stage offset-cancelled current sense amplifier (TSOCC-SA) with only two capacitors achieves a double sensing margin and a high tolerance of device mismatch. The simulation results in 28 nm CMOS technology show that the HRRG can provide a read reference that tracks PVT variations and solves the nonlinear issue of the RRAM cells. The proposed TSOCC-SA can tolerate over 64% device mismatch.

Key words: RRAMdouble sensing margindevice mismatch cancellationnonlinearity of RRAM resistancehybrid reference-cell



[1]
Yeh C W S, Wong S S. Compact one-transistor-N-RRAM array architecture for advanced CMOS technology. IEEE J Solid-State Circuits, 2015, 50, 1299 doi: 10.1109/JSSC.2015.2402217
[2]
Woo J, Yu S M. Two-step read scheme in one-selector and one-RRAM crossbar-based neural network for improved inference robustness. IEEE Trans Electron Devices, 2018, 65, 5549 doi: 10.1109/TED.2018.2875937
[3]
Chang M F, Wu C W, Kuo C C, et al. A 0.5 V 4 Mb logic-process compatible embedded resistive RAM (ReRAM) in 65 nm CMOS using low-voltage current-mode sensing scheme with 45 ns random read time. 2012 IEEE International Solid-State Circuits Conference, 2012, 434
[4]
Jain P, Arslan U, Sekhar M, et al. 13.2 A 3.6 Mb 10.1Mb/mm2 embedded non-volatile ReRAM macro in 22 nm FinFET technology with adaptive forming/set/reset schemes yielding down to 0.5 V with sensing time of 5 ns at 0.7 V. 2019 IEEE International Solid-State Circuits Conference, 2019, 212
[5]
Chen W H, Dou C M, Li K X, et al. CMOS-integrated memristive non-volatile computing-in-memory for AI edge processors. Nat Electron, 2019, 2, 420 doi: 10.1038/s41928-019-0288-0
[6]
Chou C C, Lin Z J, Lai C A, et al. A 22nm 96K × 144 RRAM macro with a self-tracking reference and a low ripple charge pump to achieve a configurable read window and a wide operating voltage range. IEEE Symposium on VLSI Circuits, 2020, 1
[7]
Na T, Song B, Kim J P, et al. Offset-canceling current-sampling sense amplifier for resistive nonvolatile memory in 65 nm CMOS. IEEE J Solid-State Circuits, 2017, 52, 496 doi: 10.1109/JSSC.2016.2612235
[8]
Dong Q, Wang Z H, Lim J, et al. A 1Mb 28nm STT-MRAM with 2.8ns read access time at 1.2V VDD using single-cap offset-cancelled sense amplifier and in situ self-write-termination. IEEE International Solid-State Circuits Conference, 2018, 480
[9]
Chang M F, Shen S J, Liu C C, et al. An offset-tolerant current-sampling-based sense amplifier for sub-100nA-cell-current nonvolatile memory. IEEE International Solid-State Circuits Conference, 2011, 206
[10]
Huang Y L, Huang R, Cai Y M, et al. A TaOx based threshold switching selector for the RRAM crossbar array memory. 12th Annual Non-Volatile Memory Technology Symposium Proceedings, 2012, 85
[11]
Chou C C, Lin Z J, Tseng P L, et al. An N40 256K × 44 embedded RRAM macro with SL-precharge SA and low-voltage current limiter to improve read and write performance. IEEE International Solid-State Circuits Conference, 2018, 478
[12]
Chakrabarti S, Jana D, Dutta M, et al. Impact of AlOx interfacial layer and switching mechanism in W/AlOx/TaOx/TiN RRAMs. 2014 IEEE 6th Int Mem Work IMW, 2014, 1
[13]
Na T, Kim J, Kim J P, et al. Reference-scheme study and novel reference scheme for deep submicrometer STT-RAM. IEEE Trans Circuits Syst I, 2014, 61, 3376 doi: 10.1109/TCSI.2014.2327337
[14]
Durlam M, Naji P J, Omair A, et al. A 1-Mbit MRAM based on 1T1MTJ bit cell integrated with copper interconnects. IEEE J Solid-State Circuits, 2003, 38, 769 doi: 10.1109/JSSC.2003.810048
[15]
Chang M F, Sheu S S, Lin K F, et al. A high-speed 7.2-ns read-write random access 4-mb embedded resistive RAM (ReRAM) macro using process-variation-tolerant current-mode read schemes. IEEE J Solid-State Circuits, 2013, 48, 878 doi: 10.1109/JSSC.2012.2230515
[16]
Trinh Q K, Ruocco S, Alioto M. Dynamic reference voltage sensing scheme for read margin improvement in STT-MRAMs. IEEE Trans Circuits Syst I, 2018, 65, 1269 doi: 10.1109/TCSI.2017.2749522
[17]
Kang W, Pang T T, Lv W, et al. Dynamic dual-reference sensing scheme for deep submicrometer STT-MRAM. IEEE Trans Circuits Syst I, 2017, 64, 122 doi: 10.1109/TCSI.2016.2606438
[18]
Zhou Y L, Cai H, Xie L, et al. A self-timed voltage-mode sensing scheme with successive sensing and checking for STT-MRAM. IEEE Trans Circuits Syst I, 2020, 67, 1602 doi: 10.1109/TCSI.2019.2960028
Fig. 1.  The TEM images of 1T1R RRAM cells.

Fig. 2.  (Color online) RRAM cell basic operations: CFs forming, Reset and Set.

Fig. 3.  (Color online) Measured I–V curve and ideal I–V curve of RRAM cell. Ideal IMP is the mid-point current of the ideal value of IHRS and ILRS. Actual IMP is the mid-point current of the measured value of IHRS and ILRS. The actual IMP is 18.4% lower than the ideal IMP.

Fig. 4.  (Color online) Reference cell structure diagrams for SP scheme, PSRC scheme and HRRG scheme.

Fig. 5.  (Color online) The distributions of cell current and the reference current.

Fig. 6.  (Color online) The maximum latency of the CSA with different reference cells.

Fig. 7.  (Color online) Schematic diagram of TSOCC-SA.

Fig. 8.  (Color online) The timing of TSOCC-SA.

Fig. 9.  (Color online) CSB-SA and proposed TSOCC-SA. Bit-cell state 1 (Icell > Iref) is assumed in the VA and VB waveforms.

Fig. 10.  (Color online) (a) Simulated ∆V [= min |VAVB|] and ∆I [= min |IAIB|] vs. VTH mismatch between transistors M1 and M2. (b) The maximum VTH mismatch that can be tolerated by TSOCC-SA at different operation voltage.

Fig. 11.  (Color online) The extra area overhead and sensing margin of several offset-cancellation techniques.

Table 1.   RRAM cell operating conditions.

LevelFormingSetResetRead
WLVG_Forming (1.8 V)VG_Set (1.0 V)VG_Reset (1.5 V)VDD (1.8 V)
BLVForming (2 V)VSet (0.68 V)0Vread (0.3 V)
SL00VReset (1.0 V)0
StateLRS(RL)LRS(RL)HRS(RH)“1”/”0”
DownLoad: CSV

Table 2.   Performances of several offset-cancellation techniques.

SAAreaStageTechnologyCancellation ability
SCOC-SA [8]One Cap128 nm60%
OCCS-SA [7]Two Caps165 nm75% or more
CSB-SA [9]Two Caps190 nm7%
TSOCC-SATwo Caps228 nm64%; 60%
DownLoad: CSV
[1]
Yeh C W S, Wong S S. Compact one-transistor-N-RRAM array architecture for advanced CMOS technology. IEEE J Solid-State Circuits, 2015, 50, 1299 doi: 10.1109/JSSC.2015.2402217
[2]
Woo J, Yu S M. Two-step read scheme in one-selector and one-RRAM crossbar-based neural network for improved inference robustness. IEEE Trans Electron Devices, 2018, 65, 5549 doi: 10.1109/TED.2018.2875937
[3]
Chang M F, Wu C W, Kuo C C, et al. A 0.5 V 4 Mb logic-process compatible embedded resistive RAM (ReRAM) in 65 nm CMOS using low-voltage current-mode sensing scheme with 45 ns random read time. 2012 IEEE International Solid-State Circuits Conference, 2012, 434
[4]
Jain P, Arslan U, Sekhar M, et al. 13.2 A 3.6 Mb 10.1Mb/mm2 embedded non-volatile ReRAM macro in 22 nm FinFET technology with adaptive forming/set/reset schemes yielding down to 0.5 V with sensing time of 5 ns at 0.7 V. 2019 IEEE International Solid-State Circuits Conference, 2019, 212
[5]
Chen W H, Dou C M, Li K X, et al. CMOS-integrated memristive non-volatile computing-in-memory for AI edge processors. Nat Electron, 2019, 2, 420 doi: 10.1038/s41928-019-0288-0
[6]
Chou C C, Lin Z J, Lai C A, et al. A 22nm 96K × 144 RRAM macro with a self-tracking reference and a low ripple charge pump to achieve a configurable read window and a wide operating voltage range. IEEE Symposium on VLSI Circuits, 2020, 1
[7]
Na T, Song B, Kim J P, et al. Offset-canceling current-sampling sense amplifier for resistive nonvolatile memory in 65 nm CMOS. IEEE J Solid-State Circuits, 2017, 52, 496 doi: 10.1109/JSSC.2016.2612235
[8]
Dong Q, Wang Z H, Lim J, et al. A 1Mb 28nm STT-MRAM with 2.8ns read access time at 1.2V VDD using single-cap offset-cancelled sense amplifier and in situ self-write-termination. IEEE International Solid-State Circuits Conference, 2018, 480
[9]
Chang M F, Shen S J, Liu C C, et al. An offset-tolerant current-sampling-based sense amplifier for sub-100nA-cell-current nonvolatile memory. IEEE International Solid-State Circuits Conference, 2011, 206
[10]
Huang Y L, Huang R, Cai Y M, et al. A TaOx based threshold switching selector for the RRAM crossbar array memory. 12th Annual Non-Volatile Memory Technology Symposium Proceedings, 2012, 85
[11]
Chou C C, Lin Z J, Tseng P L, et al. An N40 256K × 44 embedded RRAM macro with SL-precharge SA and low-voltage current limiter to improve read and write performance. IEEE International Solid-State Circuits Conference, 2018, 478
[12]
Chakrabarti S, Jana D, Dutta M, et al. Impact of AlOx interfacial layer and switching mechanism in W/AlOx/TaOx/TiN RRAMs. 2014 IEEE 6th Int Mem Work IMW, 2014, 1
[13]
Na T, Kim J, Kim J P, et al. Reference-scheme study and novel reference scheme for deep submicrometer STT-RAM. IEEE Trans Circuits Syst I, 2014, 61, 3376 doi: 10.1109/TCSI.2014.2327337
[14]
Durlam M, Naji P J, Omair A, et al. A 1-Mbit MRAM based on 1T1MTJ bit cell integrated with copper interconnects. IEEE J Solid-State Circuits, 2003, 38, 769 doi: 10.1109/JSSC.2003.810048
[15]
Chang M F, Sheu S S, Lin K F, et al. A high-speed 7.2-ns read-write random access 4-mb embedded resistive RAM (ReRAM) macro using process-variation-tolerant current-mode read schemes. IEEE J Solid-State Circuits, 2013, 48, 878 doi: 10.1109/JSSC.2012.2230515
[16]
Trinh Q K, Ruocco S, Alioto M. Dynamic reference voltage sensing scheme for read margin improvement in STT-MRAMs. IEEE Trans Circuits Syst I, 2018, 65, 1269 doi: 10.1109/TCSI.2017.2749522
[17]
Kang W, Pang T T, Lv W, et al. Dynamic dual-reference sensing scheme for deep submicrometer STT-MRAM. IEEE Trans Circuits Syst I, 2017, 64, 122 doi: 10.1109/TCSI.2016.2606438
[18]
Zhou Y L, Cai H, Xie L, et al. A self-timed voltage-mode sensing scheme with successive sensing and checking for STT-MRAM. IEEE Trans Circuits Syst I, 2020, 67, 1602 doi: 10.1109/TCSI.2019.2960028
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    Received: 11 March 2021 Revised: 22 May 2021 Online: Accepted Manuscript: 29 April 2021Uncorrected proof: 14 May 2021Published: 01 August 2021

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      Qiao Wang, Donglin Zhang, Yulin Zhao, Chao Liu, Xiaoxin Xu, Jianguo Yang, Hangbing Lv. Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes[J]. Journal of Semiconductors, 2021, 42(8): 082401. doi: 10.1088/1674-4926/42/8/082401 Q Wang, D L Zhang, Y L Zhao, C Liu, X X Xu, J G Yang, H B Lv, Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes[J]. J. Semicond., 2021, 42(8): 082401. doi: 10.1088/1674-4926/42/8/082401.Export: BibTex EndNote
      Citation:
      Qiao Wang, Donglin Zhang, Yulin Zhao, Chao Liu, Xiaoxin Xu, Jianguo Yang, Hangbing Lv. Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes[J]. Journal of Semiconductors, 2021, 42(8): 082401. doi: 10.1088/1674-4926/42/8/082401

      Q Wang, D L Zhang, Y L Zhao, C Liu, X X Xu, J G Yang, H B Lv, Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes[J]. J. Semicond., 2021, 42(8): 082401. doi: 10.1088/1674-4926/42/8/082401.
      Export: BibTex EndNote

      Low-cost dual-stage offset-cancelled sense amplifier with hybrid read reference generator for improved read performance of RRAM at advanced technology nodes

      doi: 10.1088/1674-4926/42/8/082401
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      • Author Bio:

        Qiao Wang received her BS degree in 2017 from the School of Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China. Now she is an MS student at the School of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences. Her research interests include novel non-volatile memories and their key circuit design

        Jianguo Yang received the PhD degree in microelectronics from Fudan University, Shanghai, China, in 2016. In 2019, he joined The Institute of Microelectronics of Chinese Academy of Sciences, Beijing, China, as an Associate Professor. His research interests include memory circuit design, hardware security, high performance AI chips, and in-memory computing

      • Corresponding author: yangjianguo@ime.ac.cn
      • Received Date: 2021-03-11
      • Revised Date: 2021-05-22
      • Published Date: 2021-08-10

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