Abstract pass transistor logic ptl can be a promising alternative to static cmos for deep submicron design. A new passtransistor circuit synthesis method is presented in this paper. This presentation discusses the basics of pass transistor logic, its advantages, limitation and finally implementation of boolean functionscombinational logic. Decision diagrams and pass transistor logic synthesis. Pass transistor logic xor gate using pass transistor logic. Mar 15, 2017 pass transistor logic ptl are generally superior to cmos circuits interms of delay and power consumption. It realizes a logic function using nmos pass transistors with cmos restoring buffers. Logic synthesis for large pass transistor circuits premal buch amit narayan a. After we finish bdds, we will study the boolean satisfiability sat problem. Apr, 2018 pass transistor dual value logic for lowpower cmos the increasing prominence of portable systems and the need to limit power consumption in very high density vlsi chips have led to rapid and innovative developments in. A logic synthesis system for the passtransistor logic spl. In rsp bdd, the signal flow direction is opposite to that of the forward bdd.
Sapatnekar, fellow, ieee, abstracts we address the problem of synthesizing pass transistor logic ptl, with the specic objective of delay reduction, through binary. Librarybased pass transistor logic ptl synthesis, like lean integration with pass transistors leap synthesis, has drawn significant attention to the vlsi research community. Oct 09, 2012 pass transistor logic october 9, 2012 7 8. The small circle, or bobble, on the control input of transistor tr1 indicates a pmos transistor. Spl has special two features that are the use of a long series of nmos pass transistors without intermediate buers and its \singlerail circuit structure. Several pass transistor logic families have been introduced recently, but no systematic synthesis method is available that takes into account the impact of. As integrated circuit supply voltages decrease, the disadvantages of pass transistor logic become more significant.
Highperformance multiplexerbased logic synthesis using pass. As an example application of how to synthesize circuits using bdds, here is a paper on synthesis with pass transistor logic. In recent times, the cost function of logic synthesis needs to be revisited, due to the significant impact of wiring delays. Modeling, synthesis, and simulation using vhdl book. Symbolic algorithms for layoutoriented synthesis of pass. Pass transistor logic ptl the application of ptl to nmos transistors. Application of genetic learning to pass transistor logic design and optimization in recent advances in simulated evolution and learning, edited by kay chen tan, meng hiot lim, xin yao and lipo wang, world scientific series on advances in natural computation, 2003. Sapatnekar, fellow, ieee, abstracts we address the problem of synthesizing pass transistor logic ptl, with the specic objective of delay reduction, through binary decision diagram bdd decomposition. Some logical circuits using ptl pass transistor logic october 9, 2012 8 9.
The output remains in high impedance state when gate voltage is zero. Xor has the worstcase karnaugh mapif implemented from simple gates, it requires more transistors than any other function. This paper describes a dedicated logic synthesis system for a new pass transistor logic spl which we have proposed for a highly power conscious mobile computing use. First, the transistor sizing for the special inverter circuit in the cell library is addressed, which is quite different from the. As for nmos logic circuits, selection from introduction to digital systems. Ececs 57406740 cad of digital circuits and systems utah ece.
Citeseerx document details isaac councill, lee giles, pradeep teregowda. It is a simple matter to design a series pass voltage regulator circuit like this. Differential and passtransistor cmos digital circuits. Pdf logic synthesis for large passtransistor circuits. Xor has the worstcase karnaugh mapif implemented from simple gates, it requires more transistors. Nmos devices passes a strong 0 but a weak 1 while pmos transistors pass a strong 1 but a weak 0. The simplest logic function to implement in cmos is a not gate. The book highlights the basic principles, methodologies and techniques that are common to most cmos digital designs.
An efficient logic synthesis based on passtransistor logic ptl is developed which can generate both combinational and sequential circuits. Cmos versus passtransistor logic reto zimmermann and wolfgang fichtner, fellow, ieee abstract recently reported logic style comparisons based on fulladder circuits claimed complementary passtransistor logic cpl to be much more poweref. This paper compares the use of complementary pass transistor logic cpl as more powerefficient than conventional cmos design. The entire scheme is called leap lean integration with pass transistors. In this paper, we will design a new logiccircuit synthesis. A transmission gate tg is an analog gate similar to a relay that can conduct in both directions or block by a control signal with almost any voltage potential. A general method in synthesis of passtransistor circuits. Complementary pass transistor logic a b a b b a b a b. The source and drain switch whenever the transistor is either charging or discharging the load capacitance. Bdd decomposition for delay oriented pass transistor logic.
So, when the nmos is charging up the load capacitance, the source is the input signal and the drain is the output signal. Recently reported logic style comparisons based on fulladder circuits claimed complementary passtransistor logic cpl to be much more powerefficient than complementary cmos. Taki, a survey for passtransistor logic technologies, asiapacific design automation conference, pp. Practical calculation of the area occupied by the cmos circuit. Bdd decomposition for delay oriented pass transistor logic synthesis rupesh s. Pdf topdown passtransistor logic design researchgate. Introduction to nmos and cmos vlsi systems design amar. Static and dynamic types of pass transistor logic exist, with differing properties with respect to speed, power and lowvoltage operation. In this gate if the b input is low then left nmos transistor is on and the logic value of a is copied to the output f. Efficient passtransistorlogic synthesis for sequential. The proposed logic synthesis can generate both combinational and sequence circuits based on pass transistor logic.
In this paper, we first propose a modified y3 leap cell that was originally invented by k. Transistor sizing and layout merging of basic cells in pass. The output node charges from 0 v ddv tn, and the energy drawn from the power supply for charging the output of a pass transistor is given by c l. The objective of the new logic gates and the synthesis method developed for pass transistor logic is to minimize the number of transistors used in dpl and preserve the speed of the logic.
Full adder design with 10 transistors using xorxnor gates is also reported in 6. Logic synthesis for large pass transistor circuits. Several pass transistor logic families have been introduced recently, but no systematic synthesis method is available that takes into account the impact of signal. Comparison with logic synthesis, ieee transactions on vlsi systems, vol. Basic principles of logic design in cmos technology. The book provides a comprehensive coverage of different aspects of low power circuit synthesis at various levels of design hierarchy. Analysis and synthesis of digital logic circuits digital.
Designing pass transistor logic circuits 10ff, c2 50ff the following circuit shows a general function block to realize boolean gates using pass transistor logic, such that both charging and discharging paths exist. It is a cmos based switch, in which pmos passes a strong 1 but poor 0, and nmos passes strong 0 but poor 1. Practical low power digital vlsi design emphasizes the optimization and tradeoff techniques that involve power dissipation, in the hope that the readers are better prepared the next time they are presented with a low power design problem. Realizing constructing a cmos pass gate cmos transmission gate from transistors. Highperformance multiplexerbased logic synthesis using pass transistor logic shenfu hsiao, jiasiang yeh and dayen chen department of computer science and engineering, national sun yatsen university, kaohsiung, taiwan. Decision diagrams and pass transistor logic synthesis v. The operation of the circuit can be explained as follows. Highperformance multiplexerbased logic synthesis using. Analysis and synthesis of digital logic circuits digital electronic. Nov 08, 2017 hi, these videos are not a study guide nor am i an expert. A novel technology mapping technique for bddbased circuits.
The next set of lectures is dedicated to lowpower techniques which is becoming a must not only in mobile and portable environment but are equally important issue in highperformance processor design. In electronics, pass transistor logic ptl describes several logic families used in the design of integrated circuits. However, new comparisons performed on more efficient cmos circuit realizations and a wider range of different logic cells, as well as the use of realistic. Logic synthesis enables vlsi designers to rapidly lay out the millions of transistors and interconnecting wires that form the circuitry on modern chips, without having to plot each individual logic circuit. Expert discussions cover topics ranging from the basics of logic expressions and switching theory to sophisticated programmable logic devices and the design of gaas mesfet and hemt logic circuits.
Ferrandi f, macii a, macii e, poncino m, scarsi r and somenzi f symbolic algorithms for layoutoriented synthesis of pass transistor logic circuits proceedings of the 1998 ieeeacm international conference on computeraided design, 235241. Implementation of both simple and complex logic circuits are considered in detail, with special attention paid to the design of digital systems based on complementary metaloxidesemiconductor cmos and passtransistor logic ptl technologies acceptable for use in planar microelectronics technology. Xorxnor ptl cell with 16 transistors is reported in 4. Abstractthe passtransistor based cell library and synthesis tool are constructed. In the logic synthesis domain, we have developed improved twolevel logic minimization. Mar 19, 2003 in this volume drawn from the vlsi handbook, the focus is on logic design and compound semiconductor digital integrated circuit technology. Several passtransistor logic families have been introduced recently, but no systematic synthesis method is available that takes into account the impact of signal. Figure below shows the implementation of xor function using pass transistors. Knowing the maximum current required by the load, it is possible to calculate the maximum emitter current. Pdf logic synthesis for large pass transistor circuits. Instead of using traditional cmos cell library which usually contains hundred of different types of cells, the proposed ptl synthesizer uses only three types of cells. General method in synthesis of passtransistor circuits ieee xplore. Logic gates in cmos indepth discussion of logic families in cmosstatic and dynamic, pass transistor, nonran tioed and ratioed logic n optimizing a logic gate for area, speed, energy, or robustness lowpower and highperformance circuitdesign techniques 6. Pass transistor logic ptl can be a promising alternative to static cmos for deep submicron design.
To get a basic idea, just browse through sections 1, 2 and 3. Pdf the passtransistor based cell library and synthesis tool are constructed, for the first time, to clarify the potential of. Several passtransistor logic families were introduced recently, but no systemat. Were upgrading the acm dl, and would like your input. The pass transistor based cell library and synthesis tool are constructed, for the first time, to clarify the potential of topdown passtransistor logic. In this work, we motivate the need for cad algorithms for ptl circuit design and propose decomposed bdds as a suitable logic level. So, when the nmos is charging up the load capacitance, the source is. The bobble is used to indicate that this transistor has an activelow control, which means that a logic 0 applied to the control input turns the transistor on and a logic 1 turns it off. It shows some fundamental pass transistor building blocks which became very popular in vlsi design practices.
Pass transistors require lower switching energy to charge up a node, due to the reduces voltage swing. Various pass transistor logic circuits have been reported. This technique uses the complementary properties of nmos and pmos transistors. This comes because in pass transistor logic the source and drain nodes are not fixed. Feb 11, 2016 skip bayless reacts to the dallas cowboys week 10 loss to the vikings nfl undisputed duration. This paper also appears as a book chapter robust window based. The feature of a pass transistor based cell is its multiplexer function and the opendrain structure. Logic synthesis for large pass transistor circuits proceedings of the. Nmos devices passes a strong 0 but a weak 1 while pmos transistors pass.
Some important issues related to the design of pass transistor cell library are discussed in this paper. Implementation of both simple and complex logic circuits are considered in detail, with special attention paid to the design of digital systems based on complementary metaloxidesemiconductor cmos and pass transistor logic ptl technologies acceptable for use in planar microelectronics technology. In 6, an efficient pass transistor logic synthesis method for sequential circuits is proposed. A general method in synthesis and signal arrangement in different pass transistor network topologies is analyzed. Secondly we propose a new technology dependent mapping technique and compare the. This book, electronic devices and circuit application, is the first of four books of a larger work, fundamentals of electronics. A hybrid cmos logic style adder with 22 transistors is reported 7. Pass transistor logic often uses fewer transistors, runs faster, and requires less power than the same function implemented with the same transistors in fully complementary cmos logic. An automatic logiccircuit synthesizer is developed which takes as. This paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. The truth table of xor gate is as shown in table below. This paper also appears as a book chapter robust windowbased.
Logic gates in cmos indepth discussion of logic families in cmosstatic and dynamic, passtransistor, nonran tioed and ratioed logic n optimizing a logic gate for area, speed, energy, or robustness lowpower and highperformance circuitdesign techniques 6. Cmos versus passtransistor logic solidstate circuits, ieee journal of. Highperformance multiplexerbased logic synthesis using passtransistor logic. The new logic gate represents an improvement over dpl family achieved by the elimination of the redundant branches and rearrangement of. An implemented 32bit adder using complementary cmos has a powerdelay product of less than half that of the cpl version. Im just trying to help a classmate understand the lectures note from a class. Logic synthesis for silicon and beyondsilicon multigate. Robustness1 with respect to voltage and transistor scaling as well as varying. In this work, we motivate the need for cad algorithms for. Lowpower 1bit fulladder cell using modified pass transistor logic n.
Differedtly from the work id 123 we focus od synthesizidg ode logic block at a time, and we do dot assume that bdds should be used to. Citeseerx logic synthesis for large pass transistor circuits. Practical low power digital vlsi design edition 1 by gary k. In addition, we have several instances of research efforts where logic synthesis is used in nonconventional areas such as optical networking, ip routing table compression and pass transistor logic ptl network synthesis. Asee 2014 zone i conference, april 35, 2014, university of. Ptl uses a nmos or pmos transistor to transfer charge from input node to the output node, under the control of gate voltage. The cascade carry array multiplier a novel structure of digital unsigned. It is comprised of four chapters describing the basic operation of each of the four fundamental building blocks of modern electronics. In this work, we motivate the need for cad algorithms for ptl circuit design and propose decomposed bdds as a suitable logic level representation for synthesis of ptl networks. A methodology for synthesis of pass transistor functions was established presenting a modified karnaugh map which employs the pass variables, not only logic zeroes and ones. In this paper, we propose the reversedsignalpropagation rsp bddbased lowpower pass transistor logic ptl synthesis. A general method in synthesis of passtransistor circuits d.
When vg selection from introduction to digital systems. Ip routing table compression and pass transistor logic ptl network synthesis. Robustness with respect to voltage scaling and transistor sizing, as well as generality and easeofuse, are additional advantages of cmos logic gates, especially when cellbased design and logic synthesis are targeted. The transmission gate logic is used to solve the voltage drop problem of the pass transistor logic. Logic synthesis and verification pp 197223 cite as. The section is followed by a set of papers on differential pass transistor logic which has been gaining importance in deep submicron technology. Xx, xx 2005 1 bdd decomposition for delay oriented pass transistor logic synthesis rupesh s. O c t o b e r 9 t h, 2 0 1 7 pass transistor logic 2. Hi, these videos are not a study guide nor am i an expert. In the past two decades, pass transistor logic has been shown to have smaller power and area cost compared to traditional cmos logic for some applications. It passes logic value from input to output when device is on and goes to high impedance state i.
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