Post on 07-Jan-2016
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STT-RAM Project
Initial Estimates and Results of Cell Sizing
Expected MTJ Parameters (Ilya/Pedram)
I-STT– RP ≈ 500-700Ω
– TMR ≈ 100-120%– Lowest write energy:
● VWRITE ≈ 0.6-1V
● tPULSE ≈ 1-5ns
C-STT– RP ≈ 600-800Ω
– TMR ≈ 30-50%– Lowest write energy:
● VWRITE ≈ 1.2-2.0V
● tPULSE ≈ 0.2-0.5ns
2
Reference SRAM Cell
For IBM65: F = 0.1μm SRAM Size: 0.625μm2 = 62.5F2
3
~0.
575μ
m
~1.087μm
STT-RAM Cell Sizing
For a 2 finger device, cell area is approx:0.61μm x (WFINGER + 0.2μm)
– 50F2 → 620nm/50nm x2
– 35F2 → 380nm/50nm x2
– 25F2 → 220nm/50nm x2
4
WL
BL
SL
fingersnm
m
L
W2
80
27.1
52.5 F2
27.5 F2
(OLD CELLS)
I-STT Results for “Balanced” Voltage
VWL = 1.0V
– VDD = 1V; RP ≈ 500-700Ω; TMR ≈ 100-120%
VWL = 1.2V (15-40% increase in IWRITE/VWRITE)
– VDD = 1V; RP ≈ 500-700Ω; TMR ≈ 100-120%
5
VAP→P [mV] VP→AP [mV]
50F2 300-350 410-540
35F2 250-300 270-360
25F2 190-240 160-220
IAP→P [μA] IP→AP [μA]
50F2 230-310 760-820
35F2 200-250 520-540
25F2 160-190 320-330
VAP→P [mV] VP→AP [mV]
50F2 410-470 540-667
35F2 360-480 340-410
25F2 260-330 220-300
IAP→P [μA] IP→AP [μA]
50F2 300-410 950-1100
35F2 260-340 690-730
25F2 210-260 430-450
I-STT Results for “Balanced” Current
VWL = 1.0V
– VDD = 1V; RP ≈ 500-700Ω; TMR ≈ 100-120%
VWL = 1.2V (15-40% increase in IWRITE/VWRITE)
– VDD = 1V; RP ≈ 500-700Ω; TMR ≈ 100-120%
6
VAP→P [mV] VP→AP [mV]
50F2 680-800 230-260
35F2 490-660 175-210
25F2 310-450 120-160
IAP→P [μA] IP→AP [μA]
50F2 520-680 380-460
35F2 430-490 300-350
25F2 290-310 220-250
VAP→P [mV] VP→AP [mV]
50F2 770-850 310-360
35F2 620-750 240-290
25F2 420-580 170-210
IAP→P [μA] IP→AP [μA]
50F2 550-770 510-620
35F2 490-620 410-480
25F2 380-420 300-340
C-STT Results for “Balanced” Voltage
VWL = 1.0V
– VDD = 1V; RP ≈ 600-800Ω; TMR ≈ 30-50%
VWL = 1.2V (15-40% increase in IWRITE/VWRITE)
– VDD = 1V; RP ≈ 600-800Ω; TMR ≈ 30-50%
7
VAP→P [mV] VP→AP [mV]
50F2 280-330 480-590
35F2 220-270 320-410
25F2 170-220 200-250
IAP→P [μA] IP→AP [μA]
50F2 270-360 740-800
35F2 230-290 510-530
25F2 180-210 315-325
VAP→P [mV] VP→AP [mV]
50F2 380-440 610-710
35F2 300-370 430-540
25F2 230-290 270-340
IAP→P [μA] IP→AP [μA]
50F2 360-480 890-1020
35F2 310-390 670-710
25F2 240-290 430-440
C-STT Results for “Balanced” Current
VWL = 1.0V
– VDD = 1V; RP ≈ 600-800Ω; TMR ≈ 30-50%
VWL = 1.2V (15-40% increase in IWRITE/VWRITE)
– VDD = 1V; RP ≈ 600-800Ω; TMR ≈ 30-50%
8
VAP→P [mV] VP→AP [mV]
50F2 580-740 250-280
35F2 400-560 200-230
25F2 250-370 140-170
IAP→P [μA] IP→AP [μA]
50F2 610-740 350-410
35F2 470-510 290-330
25F2 300-320 210-230
VAP→P [mV] VP→AP [mV]
50F2 700-800 340-380
35F2 530-680 270-310
25F2 330-480 190-230
IAP→P [μA] IP→AP [μA]
50F2 670-900 480-560
35F2 570-670 390-440
25F2 400-430 290-320