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. Several logic signals that perform a common function may be grouped together to form a bus. 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. Conference paper pdf available february 2000 with 371 reads. 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. This gate selects either input a or b on the basis of the value of the control signal c. In this post we will be learning about the operation and dc characteristics of pass transistor logic ptl. Pass transistors produce degraded outputs transmission gates pass both 0 and 1 well 4 7. Digital integrated circuits combinational logic prentice hall 1995 combinational logic. Performance comparison of pass transistor and cmos logic.
Highperformance multiplexerbased logic synthesis using pass. Oct 09, 2012 pass transistor logic october 9, 2012 7 8. 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. On pass transistor logic design computer science csu. 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.
On the generation of multiplexer circuits for pass transistor. For analog application, multiplexer are built of relays and transistor switches. Pass transistor multiplexers can be built using transmission gates or the lone nmos type of switch. The result calculates in active mode with voltage variation. To enhance the speed performance, a new 42 compressor and a carry lookahead adder cla, both featuring pass transistor multiplexers, have been developed. In digital processor logical and arithmetic operation executes using alu. 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. Highperformance multiplexerbased logic synthesis using. Digital integrated circuits combinational logic prentice hall 1995 overview static cmos conventional static cmos logic ratioed logic pass transistortransmission. In this paper we describes 8bit alu using low power 11 transistor full adder fa and gate diffusion input gdi based multiplexer. Binod kumar, an implementation of 1bit low power full adder based on multiplexer and pass transistor logic, ieee international conference on. Used to build logic functions there are seven basic logic gates. Design and performance analysis of barrel shifter using. The proposed multiplexer is designed and simulated using dsch 3.
Low power 8bit alu design using full adder and multiplexer. From switches to transistors, logic gates and logic circuits. Design of ltps tft current mode multiplexer and muxbased. Power and delay analysis of a 2to1 multiplexer implemented. Highperformance multiplexerbased logic synthesis using passtransistor logic.
A 54spl times54b multiplier using pass transistor multiplexers has been fabricated by 0. Four inputs are selected by two select lines and one input goes to output. This technique uses the complementary properties of nmos and pmos transistors. 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. Mos transistors silicon substrate doped with impurities. Design the 2x1 mux with 2t logic and comparing the. Tech assistant professor department of ece, krishna murthy institute of technology and engineering. Slide set 3 pass transistor logic transmission gates. Each node in the bdd trees is realized by using a 2to1 multiplexer mux of proper driving capability designed pass transistor logic. 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. It is a cmosbased switch, in which pmos passes a strong 1 but poor 0, and nmos passes strong 0 but poor 1. The pass transistor concept is based on the use of relay switches. 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.
Some logical circuits using ptl pass transistor logic october 9, 2012 8 9. For digital application, they are built from standard logic gates. It can only be connected to the sourcedrain input of another mos. Passtransistor network realizations of logic functions in general result in area. 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. The different logics are compared with respect to area and power. Though these comprise a small part of the vlsi circuit it is necessary to understand them. 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. Article pdf available in vlsi design 151 august 2002 with 183 reads. Multiplexing is the generic term used to describe the operation of sending one or more analogue or digital signals over a common transmission line at different times or speeds and as such, the device we use to do just that is called a multiplexer the multiplexer, shortened to mux or mpx, is a combinational logic circuit designed to switch one of several input lines through to a. Some use the term complementary pass transistor logic to indicate a style of implementing logic gates using dualrail encoding. From the above expression of the output, a 4to1 multiplexer can be implemented by using basic logic gates. 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.
The proposed design consists of 31 nmos and 15 pmos. To design a 2 input multiplexer using pass transistor logic. Pdf this paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. Reduction of power and current of power gating technique is less as compared to transmission gate logic tgl. Complementary pass transistor logic a b a b b a b a b. The output of the cpllike multiplexer, as shown in fig. We design the reversible circuit using dualline pass transistor logic 1 and. Abstract pass transistor logic has attracted more and more in. Transmission gate an overview sciencedirect topics. Every cpl gate has two output wires, both the positive signal and the complementary signal, eliminating the need for inverters. Transistor dflip flop based shift registers using gdi technique. On the generation of multiplexer circuits for pass transistor logic conference paper pdf available february 2000 with 21 reads how we measure reads. 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.
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. This paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. 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. Arithmetic logic unit alu is an important part of microprocessor. In contrast to static cmos primary inputs drive gate terminals. The transmission gate logic tgl using 28 transistors in the circuit is given in fig. Comparison of logic families for a 2input multiplexer briefly overview pseudonmos. 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. 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. On the generation of multiplexer circuits for pass. Jan 26, 2018 multiplexer mux 2 x 1mux design watch more videos at lecture by. 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. The multiplexer used for digital applications, also called digital multiplexer, is a. Pass transistors require lower switching energy to charge up a node, due to the reduces voltage swing.
The multiplexer used for digital applications, also called digital multiplexer, is a circuit with many input but only one output. Cml multiplexer output exhibited smaller delays according to the smaller logic swing as well as the capacitive load. A report on 2 to 1 mux using tg linkedin slideshare. Full adder using modified branch based logic style, ieee european modelling symposium, 20, pp. 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. Cmos design of area and power efficient multiplexer using. Besides this, paper also signifies more than 50% decrement in. 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.
These implementations are compared based on transistor power. Transistor implementation of proposed gate is done using virtuoso tool of cadence. Ravi pg scholarvlsi, department of ece, krishna murthy institute of technology and engineering. The inverters are then inserted all along the mux paths in order to improve the speed performance and to alleviate the voltagedrop problem.
We represent a bus by a single, heavy line, with the number of lines specified near the bus line using a slash figure 9. Thank you shrenik jain for giving this trick to implement mux using tg. 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. 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.
Block diagram of sum using pass transistor logic based multiplexer. Feb, 2001 the synthesis procedure first constructs efficient binary decision diagrams bdds for these boolean functions considering both multifunction sharing and minimum width. But there are some circuits which are made using other logics like pass transistor logic, dynamic cmos logic etc. For some types of functions, this can lead to much more efficient implementations than using gates. Logic, dual pass transistor logic and nmos techniques. Vlsi design pass transistor logicpass transistor logic. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20. Multiplexer using adiabatic logic, international journal of innovative technology and exploring engineering ijitee, vol. On the generation of multiplexer circuits for pass transistor logic. 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. Further, the pass transistor logic is implemented in multiplexer for pmos, nmos and cmos transistors separately. Each node in the bdd trees is realized by using a 2to1 multiplexer mux of proper driving capability designed passtransistor logic. Note that the circuit had been tuned to make the output change between 4. A multiplexer of 2 n inputs has n selected lines, are used to select.
The different logics are compared with respect to area and. 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. In this paper several multiplexer based pass transistor full adder topologies are presented. In earlier works using ptl the main disadvantage was that the ptl circuits were designed by hand and there was a. Performance comparison of proposed multiplexer with cmos, pass transistor and transmission gate logic design techniques is also presented. A multiplexer can be designed using various logics. Mar 25, 2016 arithmetic logic unit alu is an important part of microprocessor. 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. Vec i tno tn increases of pass transistor due to body effect.
Spice simulation reveals that ptl is superior to cmos logic in speed and power dissipation. To keep the number of components required to a minimum, it is suggested that you use 2to1 muxs. Although the cml multiplexer worked faster than the pass transistor based counterpart, it exhibited problems. The number of transistor count can be decreased by implementing pass transistor logic in the multiplexers.
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. This paper compares the use of complementary pass transistor logic cpl as more powerefficient than conventional cmos design. An efficient passtransistorlogic synthesizer using multiplexers and. In terms of pure logic functionality, these are interchangeablethey both pass or block an input signal based on the state of a control signal. 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. Abstractan efficient logic synthesis based on pass transistor logic ptl is developed. Pdf on the generation of multiplexer circuits for pass. Gowthami swarna, tutorials point india private limited. In this lecture, we will talk about another way to implement logic functions using transistors. 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. 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. The transmission gate logic is used to solve the voltage drop problem of the pass transistor logic.