EEL6323S12-HLec05-LogicalEffort-4spp

Assume now that an inverter template has the

Info icon This preview shows pages 2–4. Sign up to view the full content.

Assume now that an inverter template has the following R INV : Pull-up and pull-down resistance C INV : Input capacitance Multiply and divide by R inv C inv Delay in a Logic Gate Express delays in terms of process-independent unit d abs = d τ Logical Effort Logical Effort Captures the properties of the gate topology on it s ability to produce current Measure of how much more input capacitance a gate must present to deliver the same output current as an inverter Defined such that an inverter has logical effort of 1 d = f + p = gh + p
Image of page 2

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

3 Computing Logical Effort DEF: of a gate to the input capacitance of an inverter delivering the same output current Measure from delay vs. fanout plots Or estimate by counting transistor widths A Y A B Y A B Y 1 2 1 1 2 2 2 2 4 4 C in = 3 g = 3/3 C in = 4 g = 4/3 C in = 5 g = 5/3 Logical Effort Use delay versus fanout curves Slope of lines is the logical effort ElectricalEffort: h = C out / C in NormalizedDelay:d Inverter 2-input NAND g = p = d = g = p = d = EffortDelay:f Parasitic Delay: p 0 1 2 3 4 5 0 1 2 3 4 5 6 d = f + p = gh + p Catalog of Gates
Image of page 3
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.
  • Spring '10
  • bashir
  • Transistor, Logic gate, logical effort

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern