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درس مدارهای منطقی دانشگاه قم lc-qom.blogfa / Hazard تهیه شده توسط حسین امیرخانی

درس مدارهای منطقی دانشگاه قم http://lc-qom.blogfa.com / Hazard تهیه شده توسط حسین امیرخانی مبتنی بر اسلایدهای درس مدارهای منطقی دانشگاه امیرکبیر http://ceit.aut.ac.ir/~szamani/index_files/logic.htm. input output. input. output. time. propagation delay. Delay.

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درس مدارهای منطقی دانشگاه قم lc-qom.blogfa / Hazard تهیه شده توسط حسین امیرخانی

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  1. درس مدارهای منطقی دانشگاه قم http://lc-qom.blogfa.com/ Hazard تهیه شده توسط حسین امیرخانی مبتنی بر اسلایدهای درس مدارهای منطقی دانشگاه امیرکبیر http://ceit.aut.ac.ir/~szamani/index_files/logic.htm

  2. input output input output time propagation delay Delay • Logic gates do not produce an output simultaneously with a change in input. • There is a finite propagation delay through all gates.

  3. مثالی از هازارد • F = XZ’ + ZY • When both X & Y are 1 then F should be 1, independent of X & Y. • But because of propagation delays, if Z changes state then F will become unstable for a short time.

  4. مثالی دیگر از هازارد D B A C F A' ·A = 0 F is not always 0! D remains high for three gate delays after A changes from low to high

  5. تعریف • Glitch: • تاخيرها ممکن است باعث پالس هاي ناخواسته شوند. • Hazard: • مداري که احتمال ايجاد glitch در آن هست، هازارد دارد.

  6. 1 1 0 1 0 0 1 1 0 0 1 1 0 0 انواع • استاتيک: • استاتیک 1 • استاتیک 0 • ديناميک

  7. Definition of static hazards • A static-1 hazard is the possibility of a 0 glitch when we expect the output to remain at a nice steady 1 based on a static analysis • The same definition for static-0 hazard.

  8. مثال • تحليل کنيد:

  9. تشخيص هازارد استاتیک • A Karnaugh map can be used to detect static hazards in a two-level SOP or POS circuit.

  10. رفع هازارد استاتیک

  11. مثال

  12. Definition of dynamic hazards • The possibility of an output changing more than once as the result of a single input transition. • Detection: If there are multiple paths with different delays from the changing input to the changing output.

  13. مثال • فرض: بقية گيت ها سريعند. • سه مسير از X به F • اول تغييرات مشکي • بعد آبي غير ايتاليک • بعد آبي ايتاليک

  14. طراحي مدار بدون هازارد • Techniques for findinghazards inarbitrary circuits, are rather difficult to use. • When you require a hazard-free design, it’s best to use a circuit structurethat is easy to analyze. • In particular, two-level AND-OR circuit has no static-0 or dynamic hazards. • Static-1 hazards may exist in such a circuit but they can be found and eliminated using K-map.

  15. تمرین‌های آزمون ارشد

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