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Topic: Logical effort

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In the News (Tue 25 Jun 19)

  Logical effort - Wikipedia, the free encyclopedia
The method of logical effort, a term coined by Ivan Sutherland and Robert Sproull in 1991, is a straightforward technique used to estimate delay in a CMOS circuit.
The logical effort of an inverter is defined to be g = 1 by noting that the input capacitance of a minimum size inverter has an NMOS input capacitance of 1, while the PMOS input capacitance is two.
The logical effort of a two-input NAND gate is calculated to be g = 4/3.
en.wikipedia.org /wiki/Logical_effort   (433 words)

 Logical Effort Review
The logical effort of a gate is denoted by g, and is the average of the rising logical effort g
The falling logical effort of a gate is determined by setting the conductivity of the N transistor to be equal to the reference inverter's, scaling the P transistor size, and using the ratio of the input capacitance.
For the rising logical effort, the P transistor size is set equal to µ which means that the N transistor must be scaled down to µ/γ.
www.vlsitechnology.org /html/le_iv1.html   (760 words)

 Illinois Institute of Technology
Logical Effort can be used for both, the comparative analysis of existing circuits or topologies, as well as design guidance for the sizing of transistors and the optimum number of stages during circuit design.
The electrical effort H from c-out to c-in is 1 as both signals are connected back to back to form the carry chain.
Logical Effort has been utilized to both, estimate the delay and provide transistor sizes for the full-adder that is used to construct the ripple carry adder.
www.ece.iit.edu /~jgrad/ece583/report.htm   (1915 words)

 Principle of logical effort - Wikipedia, the free encyclopedia
The principle of logical effort is a guideline in VLSI design to determine the preferred design of several that implement a logical statement - it states that the design with the minimum propagation delay is preferred.
the electrical effort, defined as the ratio of capacitance at the output of a logic gate compared to the capacitance of the input (where the capacitance is directly proportional to the width of the CMOS gate)
These values are calculated for inverters (designed using static CMOS logic) and the values for other logic gates are defined in terms of this value.
en.wikipedia.org /wiki/Principle_of_logical_effort   (205 words)

 What is logical topology? - A Word Definition From the Webopedia Computer Dictionary
The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
Logical topologies are bound to the network protocols that direct how the data moves across a network.
The Ethernet protocol is a common logical bus topology protocol.
www.webopedia.com /TERM/L/logical_topology.html   (304 words)

 [No title]
Only 15 logical bugs, all unobtrusive, were detected in the first-pass design, and the operating system booted with first-pass chips in a prototype system.
However, because the booting simulation effort could not be restarted from the beginning, several utilities were developed that allowed the code to be replaced in the system disk image file and in simulated memory during a pause in the simulation.
Even though this effort identified no bugs in the design, it did provide a high degree of confidence that the design was ready to be released for fabrication of first-pass chips.
www.hpl.hp.com /hpjournal/dtj/vol4num3/vol4num3art3.txt   (5378 words)

 ECE 583
branching effort (b) is important in multistage design, because it allows us to model a branch in a given network as its single-path equivalent.
Estimate the total effort along each path, for example, by working backward from the outputs, combining efforts at each branch point.
Verify the number of stages for the network is appropriate for the total effort that the network bears.
www.iit.edu /~upadsau/ece583/report.htm   (878 words)

 Logical Effort Review
The calculation of the logical effort of NOR gates follows a parallel path to the one used for NAND gates.
For the rising logical effort, we scale the P transistor of the equivalent inverter to P=µ.
The P transistor conductivity coefficient is slightly different, leading to a difference in the logical efforts.
www.vlsitechnology.org /html/le_nr.html   (669 words)

 Magma Design Automation, Inc. - FixedTiming Methodology
where g is the 'logical effort', h is the 'electrical effort', and p is the basic parasitic delay.
The logical effort captures the delay due to the logical complexity of the gate: the more complex the gate, the slower it becomes.
The 'electrical effort' h is called the gain of the gate: it is the ratio of the output and the input capacitances.
www.magma-da.com /fixedtiming.html   (4689 words)

 [No title]
The value of this attribute is the logical effort of that port.
For example, a NAND gate typically has a logical effort on each input of 4/3, and an output logical effort of 2.
An inverter is defined to have an input logical effort of 1, and an output logical effort of 1.
www.staticfreesoft.com /jmanual/mchap09-09.html   (925 words)

 TAU 2006 - Stochastic Logical Effort: Designing for Timing Yield on the Back of an Envelope
Considerable effort has been expended in the EDA community during the past several years in trying to cope with the so-called statistical timing problem.
However, most of this effort has been aimed at generalizing the static timing analyzers to the statistical case in an EDA tool centric manner.
In the spirit of the standard logical effort formalism, the stochastic gate delay model we propose separates the characterization of statistical variability from the gate topology, type, size and loading information.
www.tauworkshop.com /papers06/26.html   (397 words)

 [No title]
When the Logical Effort tool runs, it annotates each digital schematic gate with a fanout ratio that can be used to size the transistors inside of that gate.
In whole-facet analysis, the Logical Effort tool iteratively applies capacitive loading constaints until the circuit fanout is determined.
It is possible to override the default calculation of the logical effort on a single node by using the Set Node Effort...
www.resultspk.net /elect_vlsi_design/chap09-12.html   (483 words)

 Logical Date Effort
It soon became apparent that all illogical forms of the date were just that, and to be abandoned because their use required longer sorts and more computer time reformatting.
I sent them a letter explaining and asking them to support logical dates by publishing the letter and changing their method of adorning their magazine with dates.
Failure to use logical, standard measurement systems recently resulted in the loss of a $300 million project to place a climate mapping satellite in orbit around Mars.
www.cowaro.com /Date/Endeavour.html   (1858 words)

 Facts about logical effort   (Site not responding. Last check: 2007-10-10)
The stage effort can be further divided into two components: a logical effort, g, which captures the intrinstic properties of the gate, and and electrical effort, h, which describes the load.
{cellspacing=10 + Logical effort for inputs of static CMOS gates, with gamma = 2
Logical Effort : Designing Fast CMOS Circuits by Ivan Sutherland, Robert...
www.supercrawler.com /Facts/logical_effort.html   (447 words)

 Logical Imagination - Technology Training, Web Design, Custom Software Development
Logical Imagination can help you develop a brand identity as well as an integrated marketing program for your business.
When Logical Imagination works with you, everything is managed using project management software and detailed schedules.
Without action plans that include timelines, budgets and clear responsibilities, all of the effort to create a coordinated marketing campaign will be lost.
www.logicalimagination.com /coordinatedcampaigns.cfm   (366 words)

 Logical Effort Review
This review of logical effort examines the values of logical effort used in the book Logical Effort, Designing Fast CMOS Circuits by Ivan Sutherland, Bob Sproull and David Harris.
Slightly different values of logical effort are proposed and have been used in the design of the cells in the vsclib.
Designing cells in a good way so as to minimise logical effort is important because the delay directly depends on it.
www.vlsitechnology.org /html/le_intro.html   (192 words)

 Criminal Justice Policy Foundation: Books: Logical Effort: Designing Fast CMOS Circuits (The Morgan Kaufmann Series in ...
The remaining chapters delve into details such as applying the method to domino circuits, passgate logic, cells with unequal rise/fall times, and a complete derivation of the method.
This book is a long overdue explanation of the "Logical Effort" approach to MOS circuit design invented by two of the authors, Sutherland and Sproull, in the late 80's.
A section contrasting the uses of the logical effort method in synchronous and asynchronous designs would also be welcome.
www.cjpf.org /shop.php?mode=Books&item=1558605576   (962 words)

 Chapman University - WCLS - Math & CS - Students - Activities - ICD Lectures - Adder
The Adder is one of the most important units in digital design for microprocessors, microcontrollers, etc. This talk will survey the different adder design topologies and analyze the advantages/disadvantages in view of the power, delay metrics.
High speed logic designers need to know where time is going in their logic.
Logical Effort is a method of answering these questions.
www.chapman.edu /wcls/MathCS/ICD/Circuits.asp   (281 words)

 what is logical effort of AND & OR gate ???
   do you mean the logical effort of  NAND gate and an AND gate is same for the same topology.....if this is true that in that case i can make two circuits of different topologies having the same logical effort.....please explain in detail......
i agree with sreeker...the logic effort for AND gate is 4/3 and for OR gate is 5/3...
The logic effort for all the gates can be buit by using the NAND gate, NOR gates.....with respect to that of inverter....and for multistage logic effort(for example, AND gate....which is formed by the combination of NAND and inverter..u just need to multiply the indivisule logic efforts of each gate...)
www.vlsibank.com /sessionspage.asp?titl_id=3507   (563 words)

 Project 1   (Site not responding. Last check: 2007-10-10)
The goal of this semester-long project is to apply the principles of skew-tolerant design and logical effort to the implementation of a 16-bit Carry Lookahead Adder (CLA) in the TSMC35 process.
The project will be spilt into three parts: (1) a “gate-level” simulation using schematics or an HDL to demonstrate an understanding of the CLA; (2) a “transistor-level” simulation of a design using skew-tolerant domino; and (3) a transistor-level simulation of an optimized netlist, applying the theory of logical effort.
For Project 1, the emphasis is on demonstrating functionality, not modeling circuit delays.
www.mrc.uidaho.edu /mrc/people/jff/545/proj1.html   (152 words)

 [No title]
The logical effort technique follows the adage “pick the lowest hanging fruit”, in that it allows for gate-level improvements after the architecture has been chosen.
Logical Effort Modeling Logical effort is an easy way to estimate the minimum possible delay in a CMOS circuit.
The stage effort is the logical effort (g) of the gate multiplied by the electrical effort (h).
www.iit.edu /~upadsau/ece583/report.doc   (2197 words)

 EDACafe: ASICs .. the Book   (Site not responding. Last check: 2007-10-10)
Find the logical effort at each input for A, B, C. Assume a logic ratio of 2.
Using logical effort, compare this with an implementation using an AOI21 cell and a NOR cell.
The branching effort is the ratio of the on-path plus off-path capacitance to the on-path capacitance.
www.edatoolscafe.com /books/ASIC/Book/CH03/CH03.a.php   (1868 words)

Logical Aspects of Computational Linguistics: 5th International Conference, LACL 2005, Bordeaux, France, April 28-30, 2005, Proceedings
Logical Aspects of Computational Linguistics: Proceedings of the 4th International Conference, Lacl 2001, Le Croisic, France, June 27-29, 2001
Logical Foundations for Cognitive Agents: Contributions in Honor of Ray Reiter
www.shopping.com /xCC-logical--media_nonfiction_category_computers   (587 words)

 Using Electric 9-12: Logical Effort
In whole-cell analysis, the Logical Effort tool iteratively applies capacitive loading constaints until the circuit fanout is determined.
There are three commands that analyze the circuit as an aid to doing Logical Effort.
This information is not generally useful, and is provided for future Logical Effort analyses.
www.staticfreesoft.com /manual/text/chap09-12.html   (583 words)

 Bookpool: Logical Effort: Designing Fast Cmos Circuits
He has made logical effort an integral part of his approach to teaching high-speed CMOS circuit design.
A detailed example of logical effort applied to the design of a multiplier.
It measures the logical effort and parasitic delay of each gate using the test setup described in Chapter 5.
www.bookpool.com /.x/iscimdet24/ss/1?qs=logical+effort   (509 words)

 plz answer these interview questions
Really, Nand is prefered over Nor, jus for its lower logical effort.
Logical effort is a measure of the ratio of output to input capacitance of a CMOS circuit.
Logical effort of Nand gate happens to be 4/3 for a nand gate, whereas 5/3 for a Nor gate, compared to that of a standard inverter.
www.vlsibank.com /sessionspage.asp?titl_id=6147   (456 words)

 Computer books at discount prices - nerdbooks.com
Designers of high-speed integrated circuits face a bewildering array of choices and too often spend frustrating days tweaking gates to meet speed targets.
Logical Effort: Designing Fast CMOS Circuits makes high speed design easier and more methodical, providing a simple and broadly applicable method for estimating the delay resulting from factors such as topology, capacitance, and gate sizes.
Offers in-depth coverage of specialized areas of application for logical effort: skewed or unbalanced gates, other circuit families (including pseudo-NMOS and domino), wide structures such as decoders, and irregularly forking circuits
www.nerdbooks.com /item.php?id=1558605576   (279 words)

 Cobb: Ethnic Socialism   (Site not responding. Last check: 2007-10-10)
Part of the problem with being one of a scientific mind is that you tend to believe that other people do things for logical reasons.
A scientist without a mean streak tends to believe the best of people, which means that he equates their passion and conviction with a commensurate amount of logical effort.
Millions of dipdunks just don't think, and it does nothing to suppress their volume or influence on others of their ilk.
www.mdcbowen.org /cobb/archives/004857.html   (344 words)

 Amazon.com: Logical Effort: Designing Fast CMOS Circuits (The Morgan Kaufmann Series in Computer Architecture and ...   (Site not responding. Last check: 2007-10-10)
electrical effort, best stage effort, parasitic delay, logical effort, branching effort, reference inverter, domino buffers, same output drive, transmission gate circuits, pulldown transistor, capacitance transformation, domino paths, pullup transistors, falling delays, evaluation transistor, domino circuits, dynamic gates, arbitration circuit, favored input, tristate inverter, dynamic inverter, unit inverter, static gates, effort borne, logic gate types
The fact that the authors picked, somewhat arbitrarily, a new definition of the technology delay parameter tau (instead of sticking to the definition established by Mead and Conway in their 1980 book) is annoying.
You will find yourself a lot logically thinking about sizing CMOS gates than before when you just try to tweak the numbers and repeat simulations.
www.amazon.com /Logical-Effort-Designing-Circuits-Architecture/dp/1558605576   (1705 words)

 Publisher description for Library of Congress control number 98053860
Publisher description for Logical effort : designing fast CMOS circuits / Ivan Sutherland, Robert Sproull, David Harris.
The brainchild of circuit and computer graphics pioneers Ivan Sutherland and Bob Sproull, "logical effort" will change the way you approach design challenges.
* Offers in-depth coverage of specialized areas of application for logical effort: skewed or unbalanced gates, other circuit families (including pseudo-NMOS and domino), wide structures such as decoders, and irregularly forking circuits.
www.loc.gov /catdir/description/els033/98053860.html   (290 words)

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