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STT-RAM Project. Initial Estimates and Results of Cell Sizing. Expected MTJ Parameters (Ilya/Pedram). I-STT R P ≈ 500-700 Ω TMR ≈ 100-120% Lowest write energy: V WRITE ≈ 0.6-1V t PULSE ≈ 1-5ns C-STT R P ≈ 600-800 Ω TMR ≈ 30-50% Lowest write energy: V WRITE ≈ 1.2-2.0V
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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
Reference SRAM Cell • For IBM65: F = 0.1μm • SRAM Size: 0.625μm2 = 62.5F2 ~1.087μm ~0.575μm
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 27.5 F2 52.5 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%
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%
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%
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%