Pass transistor logic families complementary pass transistor logic family dual pass transistor logic family swing restored pass transistor logic family 31. A cmos transmission gate can be constructed by parallel combination of nmos and pmos transistors, with complementary gate signals. Tie the input logic of i0 to 1 and i1 to 0 and calculate. Design of gdi based power efficient combinational circuits. The device features independent enable inputs ne and common data select inputs s0 and s1. The output of the cpllike multiplexer, as shown in fig. Feb 11, 2016 skip bayless reacts to the dallas cowboys week 10 loss to the vikings nfl undisputed duration. Highperformance multiplexerbased logic synthesis using pass. Figure6 shows the circuit level diagram of the 2x1 mux. This paper compares the use of complementary passtransistor logic cpl as more powerefficient than conventional cmos design. Implement an xor gate using minimum number of transistors. Its not super easy to see how this works by just staring at it, but i suggest you play with the inputs and see the results at each stage of the circuit to get a handle of how it works. The main advantage of using transmission gate logic is that it minimizes the number of transistors used for implementation of any logic circuit by. In this paper, we present a selfchecking full adder based on the double pass transistor technology.
Tie the input logic of i0 to 1 and i1 to 0 and calculate the output on the basis of select line and mux truth table. The most basic type of multiplexer device is that of a oneway rotary. 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. On the generation of multiplexer circuits for pass transistor. Skip bayless reacts to the dallas cowboys week 10 loss to the vikings nfl undisputed duration. Its not super easy to see how this works by just staring at it, but i suggest you play with the inputs and see the results at each stage of.
And the full adder is implemented using 8 transistors. 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. How to design a 4 by 1 multiplexer using nand or nor. Implementing logic in cmos the university of texas at. In 1 kang has proposed an adder design with pulldown and pullup network using 28 transistors 3. Vlsi design pass transistor logicpass transistor logic. In earlier works using ptl the main disadvantage was that the ptl circuits were designed by hand and there was a. If you will write down the logic equations for a 4 to 1 multiplexor, then the logic will become obvious. Double pass transistor logic dpl the basic difference of pass transistor logic compared to the cmos logic style is that the source side of the logic transistor networks is connected to some input signals instead of the power lines. Problems design 4 to 1 multiplexor using transmissiongates. Implementing multiplexers with passtransistor logic. The pass transistor logic reduces the parasitic capacitance and gdi logic increase the speed of the operation. Pass transistor logic families there are two main pass transistor circuit styles.
Multiplexers and demultiplexers are often confused with one another by students. Although they appear similar, they certainly perform di. If youve read the previous articles on pass transistor logic ptl, you know that this approach to digital design is good and bad. In this design i use and, a not gate, and an or gate. Design the 2x1 mux with 2t logic and comparing the. Highperformance multiplexerbased logic synthesis using passtransistor logic article pdf available in vlsi design 151 august 2002 with 200 reads how we measure reads. Multiplexers, or muxs, can be either digital circuits made from high speed logic gates used to switch digital or binary data or they can be analogue types using transistors, mosfets or relays to switch one of the voltage or current inputs through to a single output. 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. Full adder using xorxnor ptl cell with 16 transistors is reported in 4. Now that you have been exposed to analog signals as they appear in the digital world, this should make sense.
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. Alternatively, this function can also be realized by an 8x1 mux using the three variables a, b, and c as the three selections, and the function values corresponding to the eight minterms as the eight mux inputs. The aim of the project is to drive the current from the fet with selected wl to the output of the multiplexer. A multiplexers mux is a combinational logic component that has several inputs and only one output. The first thing to do is to get a 2 x 1 mux working. As integrated circuit supply voltages decrease, the disadvantages of pass transistor logic become more significant. In this lecture, we will talk about another way to implement logic functions using transistors. Passtransistor multiplexers can be built using transmission gates or the lone nmos type of switch. How do voltage levels at the output of this gate differ from that of the passtransistor multiplexer in the. A multiplexer can be designed using various logics.
Slide set 3 pass transistor logic transmission gates. Implementing multiplexers with passtransistor logic technical. 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. Passtransistor logic families there are two main passtransistor circuit styles. Some logical circuits using ptl pass transistor logic october 9, 2012 8. Mar 03, 2014 pass transistor logic families complementary pass transistor logic family dual pass transistor logic family swing restored pass transistor logic family 31. Efficient design of low power alu using ptlgdi logic full adder. Design of arthematic logic unit using gdi adder and multiplexer. Demultiplexer design using transmission gate on 90nm technology. The voltage on a node is a logic one, the complementary logic zero is applied to activelow a node. The advantages of cmos logic are 1 robustness, 2 transistor sizing, 3 reliable operation at low speed.
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. The multiplexers were designed using pass transistor logic. The advantage is that one passtransistor network either nmos or pmos is sufficient to perform the logic operation, which results in a smaller number of transistors and smaller input loads 3. The pass electronic transistor logic reduces the parasitic capacitance and modified gdi logic increase the speed of the operation. The multiplexers were designed mistreatment pass electronic transistor logic. Static and dynamic types of pass transistor logic exist, with differing properties with respect to speed, power and lowvoltage operation. These implementations are compared based on transistor power. Four transmission gates square measure are used to create an mux structure.
A somewhat more complex 2to1 mux has one additional input often called. Can someone please explain me how to design a logic circuit of 4x1 mux using 2x1 muxes and logic gates. The passtransistor 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. It permits each transistor to conduct and pass the signal from in to out. This gate selects either input a or b on the basis of the value of the control signal c. Efficient design of low power alu using ptlgdi logic full. Vlsi design pass transistor logicpass transistor logic adapted from rabaeys digital integrated circuits, 2002, j. For some types of functions, this can lead to much more efficient implementations than using gates. The output of the 4x1 multiplexer stage is passed as input to the full adder. In existing methodology alu is intended mistreatment 4x1 mux, 2x1 mux and full adder. The pass transistor logic reduces the number of transistor.
The inverters are then inserted all along the mux paths in order to improve the speed performance and to alleviate the voltagedrop problem. For example, a 21 mux with select line s, output y, and inputs a and b might be y s and a or not s and b and the obvious implementation. Once the voltage on activelow node a is a logic zero, the. A selfchecking cmos full adder in double pass transistor.
The aim of this experiment is to design and plot the characteristics of a 4x1 digital multiplexer using pass transistor and transmission gate logic. Virtual lab indian institute of technology guwahati. Mux directs one of the inputs to its output line by using a control bit word selection line to its select lines. Complementry pass transistor logic style traditionally, handcrafted ptl has been successfully used to implement digital systems which are. Demultiplexer design using transmission gate on 90nm. Introduction 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. In general the bad outweighs the good, as demonstrated by the preponderance of inverterbased logic in digital ics of all kinds. 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 advantage is that one pass transistor network either nmos or pmos is sufficient to perform the logic operation, which results in a smaller number of transistors and smaller input loads 3. This design is simple and efficient in terms of area and timing. In existing method alu is designed using 4x1 mux, 2x1 mux and full adder. Some logical circuits using ptl pass transistor logic october 9, 2012 8 9. 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. The conventional cmos transistor representation of an 8.
Complementary pass transistor logic complementary pass transistor logic 7 consists of. Pdf highperformance multiplexerbased logic synthesis using. A selfchecking cmos full adder in double pass transistor logic. Highperformance multiplexerbased logic synthesis using.
Area, power, delay performance analysis of logic element. If any one of the select line is to be on means the. Each node in the bdd trees is realized by using a 2to1 multiplexer mux of proper driving capability designed passtransistor logic. Double passtransistor logic dpl the basic difference of pass transistor logic compared to the cmos logic style is that the source side of the logic transistor networks is connected to some input signals instead of the power lines. A 16x1 mux is created using 5 4x1 mux as shown in the fig 7. Implementation using passtransistor 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 passtransistor logic, such as cpl or dpl. Some use the term complementary pass transistor logic to indicate a style of implementing logic gates using dualrail encoding. A 2to1 mux is commonly diagrammed as follows, in a way that hides its innerworkings, giving us a new building block from which more complex multiplexers can be built.
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