The multiplexer used for digital applications, also called digital multiplexer, is a. Digital integrated circuits combinational logic prentice hall 1995 overview static cmos conventional static cmos logic ratioed logic pass transistortransmission. A 54spl times54b multiplier using pass transistor multiplexers has been fabricated by 0. Although the cml multiplexer worked faster than the pass transistor based counterpart, it exhibited problems. 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. Vec i tno tn increases of pass transistor due to body effect. Jan 26, 2018 multiplexer mux 2 x 1mux design watch more videos at lecture by. Digital integrated circuits combinational logic prentice hall 1995 combinational logic. We design the reversible circuit using dualline pass transistor logic 1 and. To design a 2 input multiplexer using pass transistor logic. The inverters are then inserted all along the mux paths in order to improve the speed performance and to alleviate the voltagedrop problem. The result calculates in active mode with voltage variation.
In this paper several multiplexer based pass transistor full adder topologies are presented. 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. On the generation of multiplexer circuits for pass transistor. Article pdf available in vlsi design 151 august 2002 with 183 reads. Vlsi design pass transistor logicpass transistor logic. Cmos logic families many families of logic exist beyond static cmos comparison of logic families for a 2input multiplexer briefly overview pseudonmos differential cvsl dynamicdomino complementary passgate. Pass transistor logic has attracted more and more in terest during last years, since it has proved to be an attrac tive alternative to static cmos designs with. Nmos devices passes a strong 0 but a weak 1 while pmos transistors pass. Comparison of logic families for a 2input multiplexer briefly overview pseudonmos.
In earlier works using ptl the main disadvantage was that the ptl circuits were designed by hand and there was a lack of automatic synthesis tools. Design and performance analysis of barrel shifter using. When control signal c is logic low the output is equal to the input a and when control signal c is logic high the output is equal to the input b. In this lesson we will study digital multiplexing in which the number of inputs is a power of two 2, 4, 8, 16, and there is one output.
But there are some circuits which are made using other logics like pass transistor logic, dynamic cmos logic etc. In this lecture, we will talk about another way to implement logic functions using transistors. Full adder using modified branch based logic style, ieee european modelling symposium, 20, pp. Every cpl gate has two output wires, both the positive signal and the complementary signal, eliminating the need for inverter six transistor cmos sram cell. Each node in the bdd trees is realized by using a 2to1 multiplexer mux of proper driving capability designed passtransistor logic. Low power 8bit alu design using full adder and multiplexer. To enhance the speed performance, a new 42 compressor and a carry lookahead adder cla, both featuring pass transistor multiplexers, have been developed. On the generation of multiplexer circuits for pass transistor logic.
Transmission gate an overview sciencedirect topics. Other authors use the term complementary pass transistor logic cpl to indicate a style of implementing logic gates using dualrail encoding. For digital application, they are built from standard logic gates. Thus the final circuit for barrel shifter using conventional design i. Pdf on the generation of multiplexer circuits for pass. The different logics are compared with respect to area and. Though it has high speed due to low input capacitance, it has limited capacity to drive a load. Implementing multiplexers with passtransistor logic. 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. For some types of functions, this can lead to much more efficient implementations than using gates.
This paper compares the use of complementary pass transistor logic cpl as more powerefficient than conventional cmos design. Some logical circuits using ptl pass transistor logic october 9, 2012 8 9. From switches to transistors, logic gates and logic circuits. An efficient passtransistorlogic synthesizer using multiplexers and. Furthermore, a comparison between the performances of both the configurations in terms of power dissipation, chip area, power supply and drive current levels are analyzed. In the pass transistor logic the input to the gate acts as the controlling input and depending on the value of control variable,the input at the source end of transistor appears at the drain end or in other words the control variable controls a pass tran.
Though these comprise a small part of the vlsi circuit it is necessary to understand them. Construct a 4to1 mux if you are in a classroom setting, and each lab group of students has constructed a 2to1 mux, you might find it interesting, challenging, and fun to connect three lab group 2to1 muxs together into a 4to1 mux. A report on 2 to 1 mux using tg linkedin slideshare. Highperformance multiplexerbased logic synthesis using passtransistor logic. Some use the term complementary pass transistor logic to indicate a style of implementing logic gates using dualrail encoding. These implementations are compared based on transistor power. Arithmetic logic unit alu is an important part of microprocessor. The proposed design consists of 31 nmos and 15 pmos. A multiplexer can be designed using various logics. Pass transistor adiabatic logic pal splitrail charge recovery logic scrl.
In contrast to static cmos primary inputs drive gate terminals. Design of ltps tft current mode multiplexer and muxbased. Ravi pg scholarvlsi, department of ece, krishna murthy institute of technology and engineering. Mos transistors silicon substrate doped with impurities. The proposed multiplexer is designed and simulated using dsch 3.
The transmission gate logic is used to solve the voltage drop problem of the pass transistor logic. This technique uses the complementary properties of nmos and pmos transistors. In this paper, two different mux is designed one is using universal gates and other is using pass transistor logic, in nand gate design no of transistors used are 14 while in pass transistor logic the no of transistors used are 6. Other authors use the term complementary pass transistor logic cpl to indicate a style of implementing logic gates where each gate consists of a nmos pass transistor network, followed by a cmos output inverter. Conference paper pdf available february 2000 with 371 reads. We represent a bus by a single, heavy line, with the number of lines specified near the bus line using a slash figure 9. From the above expression of the output, a 4to1 multiplexer can be implemented by using basic logic gates. Pass transistor logic ptl has proved to be an attractive alternative to static cmos designs with respect to area, performance and power consumption 23, 15, 9, 12.
Abstractan efficient logic synthesis based on pass transistor logic ptl is developed. Further, the pass transistor logic is implemented in multiplexer for pmos, nmos and cmos transistors separately. To keep the number of components required to a minimum, it is suggested that you use 2to1 muxs. Implementation using pass transistor logic cell library once the boolean functions are represented by bdd trees, we can easily realize the logic functions by replacing each node in the bdd trees with a 2to1 multiplexer designed using pass transistor logic, such as cpl or dpl. Binod kumar, an implementation of 1bit low power full adder based on multiplexer and pass transistor logic, ieee international conference on. Four inputs are selected by two select lines and one input goes to output. Reduction of power and current of power gating technique is less as compared to transmission gate logic tgl. Gowthami swarna, tutorials point india private limited. Finally a 16 bit arithmetic logic unit is designed using mixed logic families such as cmos for basic logic functions, pseudonmos for and logic and pass transistor logic for multiplexers, in order.
A multiplexer of 2 n inputs has n selected lines, are used to select. It can only be connected to the sourcedrain input of another mos. Feb, 2001 the synthesis procedure first constructs efficient binary decision diagrams bdds for these boolean functions considering both multifunction sharing and minimum width. Complementary pass transistor logic a b a b b a b a b. On pass transistor logic design computer science csu. Abstracts scaling characteristics are compared on some basic logic cells that are 2input multiplexer and 2input nand of cmos logic and pass transistor logic ptl. Pass transistors require lower switching energy to charge up a node, due to the reduces voltage swing. Highperformance multiplexerbased logic synthesis using pass. One of the key steps in the use of transmission gates and pass transistors for logic implementation is the identification of pass variables to replace the 1. Performance comparison of pass transistor and cmos logic. Passtransistor network realizations of logic functions in general result in area. Multiplexer using adiabatic logic, international journal of innovative technology and exploring engineering ijitee, vol. Transistor dflip flop based shift registers using gdi technique.
Performance comparison of proposed multiplexer with cmos, pass transistor and transmission gate logic design techniques is also presented. Based on the result of the analysis, some of the tradeoffs are made in the. It should be noted that although transmissiongate based and pass transistor based designs can reduce silicon area, placing a pass transistor on a normal signal path could lead to difficulty in testing, because a highimpedance state is introduced at the output of the pass transistor when the pass transistor is stuck at the off state. Pass transistors, transmission gates and gate diffusion input are different techniques in design of low power digital circuits. Multiplexer handle two type of data that is analog and digital.
Logic, dual pass transistor logic and nmos techniques. Pdf this paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. Thank you shrenik jain for giving this trick to implement mux using tg. The main idea is to introduce the design of high performance and low. It is a cmosbased switch, in which pmos passes a strong 1 but poor 0, and nmos passes strong 0 but poor 1. For analog application, multiplexer are built of relays and transistor switches. On the generation of multiplexer circuits for pass transistor logic conference paper pdf available february 2000 with 21 reads how we measure reads. In earlier works using ptl the main disadvantage was that the ptl circuits were designed by hand and there was a. Besides this, paper also signifies more than 50% decrement in. In this paper we describes 8bit alu using low power 11 transistor full adder fa and gate diffusion input gdi based multiplexer. Used to build logic functions there are seven basic logic gates. The multiplexer used for digital applications, also called digital multiplexer, is a circuit with many input but only one output. Power and delay analysis of a 2to1 multiplexer implemented.
From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20. In terms of pure logic functionality, these are interchangeablethey both pass or block an input signal based on the state of a control signal. Each node in the bdd trees is realized by using a 2to1 multiplexer mux of proper driving capability designed pass transistor logic. Cmos design of area and power efficient multiplexer using. In this post we will be learning about the operation and dc characteristics of pass transistor logic ptl. Block diagram of sum using pass transistor logic based multiplexer. On the generation of multiplexer circuits for pass transistor logic christoph scholl bernd becker institute of computer science albertludwigsuni versity d 79110 freiburg im breisgau, germany email.
The pass transistor logic attempts to reduce the number of transistors to implement a logic by allowing the primary inputs to drive gate terminals as well as sourcedrain terminals. A multiplexer or mux is a combinational circuits that selects several analog or digital input signals and forwards the selected input into a single output line. Transistor implementation of proposed gate is done using virtuoso tool of cadence. Abstract pass transistor logic has attracted more and more in. Tech assistant professor department of ece, krishna murthy institute of technology and engineering. Oct 09, 2012 pass transistor logic october 9, 2012 7 8. The pass transistor concept is based on the use of relay switches. This paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. Pass transistors produce degraded outputs transmission gates pass both 0 and 1 well 4 7. The aim of this experiment is to design and plot the characteristics of a 4x1 digital multiplexer using pass transistor and transmission gate logic introduction. Mos transistors silicon substrate doped with impurities adding or cutting away insulating glass sio 2 adding wires made of polycrystalline silicon polysilicon, poly or metal, insulated from the substrate by sio 2 drain source gate n n drain source gate sio 2 insulator ptype doped substrate drain source gate nmos transistor. On the generation of multiplexer circuits for pass.
Highperformance multiplexerbased logic synthesis using. The demultiplexer is a combinational logic circuit designed to switch one common input line to one of several seperate output line the data distributor, known more commonly as a demultiplexer or demux for short, is the exact opposite of the multiplexer we saw in the previous tutorial. Implementation of low power cmos full adders using pass. Slide set 3 pass transistor logic transmission gates. Mar 25, 2016 arithmetic logic unit alu is an important part of microprocessor. Every cpl gate has two output wires, both the positive signal and the complementary signal, eliminating the need for inverters. Differential cascode voltage switch logic with pass gate dcvspg, swing restored pass transistor logic srpl6, double pass transistor logic dpl, cmos transmission gate6, pushpull pass transistor logic ppl, lean integrated pass gate logic leap and 2t multiplexer are considered to implement 2to1 multiplexer. Transistor logic and dpl double pass transistor logic. In digital processor logical and arithmetic operation executes using alu. 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. Note that the circuit had been tuned to make the output change between 4. Several logic signals that perform a common function may be grouped together to form a bus. The transmission gate logic tgl using 28 transistors in the circuit is given in fig.
The different logics are compared with respect to area and power. The number of transistor count can be decreased by implementing pass transistor logic in the multiplexers. Cml multiplexer output exhibited smaller delays according to the smaller logic swing as well as the capacitive load. This gate selects either input a or b on the basis of the value of the control signal c. The output of the cpllike multiplexer, as shown in fig.
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