Minimum IREAD/IWRITE for Viability Sharing MTJs Minimum IREAD/IWRITE for Viability

Definition of IREAD/IWRITE IREAD: probability of switching < threshold (i.e. 10-9, prob of switching < 0.01% for 100,000 reads) IWRITE: probability of switching > threshold (i.e. 1-10-9, prob of not switching < 0.01% for 100,000 writes)

Minimum IREAD/IWRITE for Sharing For (P→AP): For (AP→P): WL<1> WL<2> BL<1> BL<2>

Distribution of MIN IREAD/IWRITE Assuming Gaussian distributions for RP and TMR, we can derive the distribution for min IREAD/IWRITE

Results TMR = 120% Rp = 300Ω σTMR = 10% σRp = 20Ω TMR = 120% Rp = 450Ω XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.33333 0.35483 0.41691 0.52381 σAP→P 0.01691 0.02106 0.02425 0.02935 σP→AP 0.00452 0.00645 0.00839 0.01290 IREAD/IWRITE + 3σAP→P 0.38406 0.41804 0.48965 0.61187 IREAD/IWRITE + 3σP→AP 0.34690 0.37421 0.44208 0.56252 XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.33333 0.35484 0.41691 0.52381 σAP→P 0.01467 0.01848 0.02145 0.02641 σP→AP 0.00301 0.00430 0.00557 0.00857 IREAD/IWRITE + 3σAP→P 0.37736 0.41027 0.48127 0.60304 IREAD/IWRITE + 3σP→AP 0.34237 0.36772 0.43363 0.54953 Typical I-STT TMR = 200% Rp = 300Ω σTMR = 10% σRp = 20Ω TMR = 120% Rp = 300Ω σTMR = 20% σRp = 40Ω XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.34426 0.42857 0.49367 0.60000 σAP→P 0.01752 0.02099 0.02342 0.02692 σP→AP 0.00452 0.00646 0.00839 0.01291 IREAD/IWRITE + 3σAP→P 0.39683 0.49153 0.56392 0.68076 IREAD/IWRITE + 3σP→AP 0.35784 0.44795 0.51884 0.63872 XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.33333 0.35484 0.41691 0.52381 σAP→P 0.03344 0.04153 0.04767 0.05746 σP→AP 0.00921 0.01314 0.01708 0.02627 IREAD/IWRITE + 3σAP→P 0.43366 0.47942 0.55993 0.69619 IREAD/IWRITE + 3σP→AP 0.36096 0.39426 0.46816 0.60262 Higher TMR for Reading TMR = 200% Rp = 450Ω σTMR = 8% σRp = 15Ω TMR = 50% Rp = 600Ω σTMR = 5% σRp = 10Ω C-STT XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.34426 0.42857 0.49367 0.60000 σAP→P 0.01130 0.01375 0.01556 0.01836 σP→AP 0.00226 0.00323 0.00418 0.00643 IREAD/IWRITE + 3σAP→P 0.37816 0.46984 0.54036 0.65507 IREAD/IWRITE + 3σP→AP 0.35105 0.43825 0.50622 0.61929 XWRITE 0.35 0.5 0.65 1 IREAD/IWRITE 0.33333 0.42857 σAP→P 0.00728 0.00950 0.01138 0.01479 σP→AP 0.00116 0.00163 0.00211 0.00322 IREAD/IWRITE + 3σAP→P 0.35516 0.36183 0.36749 0.47294 IREAD/IWRITE + 3σP→AP 0.33681 0.33822 0.33965 0.43824

Summary Sharing Degrades Read Margin → Need Larger TMR Larger TMR → Larger IREAD/IWRITE IREAD/IWRITE ≈ 33% to 50%