Nov 23, 2016 the main and just about only advantage is that pass transistors make significantly denser multiplexers than using only static cmos 2 transistors per input compared to 6 transistors per input for a nand based mux. This paper presents the design and implementation of a lowenergy asynchronous logic topology. Cmos and pass transistor logic 2 institute of microelectronic systems nchannel transistors produce a logic 0 at the output when a logic 1 is apllied on its gate. 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. The main and just about only advantage is that pass transistors make significantly denser multiplexers than using only static cmos 2 transistors per input compared to 6 transistors per input for a nand based mux. For various values of frequency the power characteristics of three pass transistor logic styles are compared at vdd0. Complementary pass transistor logics cpl has provided a drastic reduction in the power compared to cmos logic. Design of low power reversible decoder using cmos pass. Various circuit and logic design styles used in contemporary high performance processors have been. Index terms adder circuits, cpl, complementary cmos, lowvoltage lowpower logic styles, pass. Pass transistor logic department of computer science.
Automated design for currentmode passtransistor logic blocks. Testing complementary passtransistor logic circuits a. Slide set 3 pass transistor logic transmission gates. Indeed, designing highspeed lowpower circuits with. To explain the properties of complementary cmos gates. Pass transistor logic pass transistor logic involves nmos or pmos transistors to transfer the charge from one node of a circuit to another node under the control of mos gate voltage. 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.
Testing complementary pass transistor logic circuits a. 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. Pass transistor logic the variation of the node voltage vx as a function of time shows that if the voltage at node x cannot exceed a maximum of the above expression assumes that vsb is at logic 0. It passes logic value from input to output when device is on and goes to high impedance state i. Passtransistor logic is most effective in the implementation of boolean functions when the vectors are in the same format. A selfchecking cmos full adder in double pass transistor logic. Differential and passtransistor cmos logic for high. This study uses differential pass transistor methodology for implementing and evaluating boolean functions.
We shall develop the characteristics of cmos logic through the inverter structure, and later discuss. Transistors are used as switches to pass logic levels between nodes of a circuit, instead of as switches connected directly to supply voltages. Pass transistor logic xor gate using pass transistor logic. A srplceu has the same disadvantages as a cplcell 6. Lowvoltage lowpower logic styles, pass transistor logic, vlsi circuit design. National central university ee6 vlsi design logic gate design 8input and gate approach comparison of approaches to designing an 8input and gate delay stage 1ns delay stage 2ns delay stage 3ns delay stage 4ns total delay spice ns 1 nd8inv 2 nd4nr2 3 nd2nr2 nd2inv 2. What is the logic function implemented by the cmos transistor network. Complementary passtransistor logic 7 consists of complementary inputs outputs, a nmos passtransistor network, and cmos output inverters. Implementation of low power cmos full adders using pass. What is the main differencepoint of using passtransistor. Vtn vtp vdd vdd vctrl vdd vout cout vin vctrl cmos transmission gate vctrl vctrl vin vout symbol. This paper has spread the focus on low power adder design based on ptls and achieved 2.
Vlsi design pass transistor logicpass transistor logic adapted from rabaeys digital integrated circuits, 2002, j. Design of dynamic pass transistor logic circuits using 123 decision diagrams, ieee trans. The truth table of xor gate is as shown in table below. Cmos and pass transistor logic solution suggestions 4. Other authors use the term complementary pass transistor logic cpl to indicate a style. In this lecture, we will talk about another way to implement logic functions using transistors. In electronics, pass transistor logic ptl describes several logic families used in the design of. Differential and passtransistor cmos logic for high performance systems. It reduces the count of transistors used to make different logic gates, by eliminating redundant transistors. Oct 09, 2012 in electronics pass transistor logic ptl describes several logic families used in the design of integrated circuits.
In ptl, use of either nmos or pmos is enough to send the data. Figure below shows the implementation of xor function using pass transistors. For some types of functions, this can lead to much more efficient implementations than using gates. One of the first papers examining passtransistor logic and formalizing passtransistor design style was published by whitaker, in 1983 whitaker, electronics. Raju institute of technology, narsapur, medak, india. Nmos devices passes a strong 0 but a weak 1 while pmos transistors pass a strong 1 but a weak 0.
Introduction conventional static cmos has been a technique of choice in most processor design 1. Implementation of full adder using cmos logic styles based. It is one of the logic styles which use less number of transistors than the regular cmos logic style. Alternatively, static pass transistor circuits have also been suggested for lowpower applications 2. This technique uses the complementary properties of nmos and pmos transistors. Problem on complex cmos logic gates gate ece 2012 solved paper electron devices duration. Differential and passtransistor cmos digital circuits. The design has been modelled and analyzed using tanner eda with tsmc. To explain the issues related to passtransistor design. Hello and welcome original pdf to todays lecture on passtransistor logic circuits this is the page replacement policies. Design of sequential circuit using low power adiabatic. In electronics pass transistor logic ptl describes several logic families used in the design of integrated circuits. The pass transistor logic ptl describes numerous logic used in the design of integrated circuits.
Asynchronous computing in low power based sense amplifier pass transistor logic john pragasam. Design of dynamic passtransistor logic circuits using 123 decision diagrams, ieee trans. It shows some fundamental pass transistor building blocks which became. Testing complementary passtransistor logic circuits.
The output of combinational logic circuits is dependent on the combination of the inputs. Pass transistor chain can be used in design of regular array based structures such as roms plas, multiplexers etc strength of output signal the strength of a. Logic synthesis for large pass transistor circuits premal buch amit narayan a. In electronics, pass transistor logic ptl describes several logic families used in the design of integrated circuits. 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 circuit design techniques 6. Passtransistor logic how is passtransistor logic abbreviated. The twophase powerclock scheme is more suitable for the design of. To explain the issues related to pass transistor design. Pass transistor logic is most effective in the implementation of boolean functions when the vectors are in the same format. Static cmos circuit at every point in time except during the switching transients each gate output is connected to either v dd or v ss via a lowresistive path the. Microelectronic systems vlsi design of integrated circuits 4. Hello and welcome original pdf to todays lecture on pass transistor logic circuits this is the page replacement policies.
Automated design for currentmode passtransistor logic blocks by matthew david pierson research project submitted to the department of electrical engineering and computer sciences, university of california at berkeley, in partial satisfaction of the requirements for. Thumb rules are then used to convert this design to other more complex logic. Complementary pass transistor logic complementary pass transistor logic 7 consists of. Journal of chemical and pharmaceutical sciences issn. Digital multiplier design using cmos and pass transistor logics. Although generating differential signals require extra circuitry, complex gates such as. Therefore, new logic families that address the power and performance challenges must be explored 1. Elsevier microelectronics journal 29 1998 679688 differential and passtransistor cmos logic for high performance systems vojin g. The transmission gate logic is used to solve the voltage drop problem of the pass transistor logic. Bdd decomposition for delay oriented pass transistor logic. Design of low power reversible decoder using cmos pass transistor logic shaik raffiq 1, t. V s will initially charge up quickly, but the tail end of the transient is slow.
The paper describes how the logic functions can be efficiently and optimally built using passtransistor logic. The 3t nand and nor gates design is based on cmos inverter and ptl. Elsevier microelectronics journal 29 1998 679688 differential and pass transistor cmos logic for high performance systems vojin g. Pass transistor logic ptl are generally superior to cmos circuits interms of delay and power consumption. Free download cmos logic circuit design ebook circuitmix. Combinational logic gates in cmos purdue university.
The paper investigates low power characteristics of complementary pass transistor logic cpl circuits using ac power supply. Passtransistor logic families there are two main passtransistor circuit styles. Passtransistorlogic xor gate using pass transistor logic. The twophase powerclock scheme is more suitable for the design of flipflops and sequential. Output voltage degradation occurs across the pmos and nmos pass transistors due to threshold voltage drop while passing the logic zero or logic one respectively in relation to the input. On pass transistor logic design computer science csu. Solution the logic function is the transistor sizes are given in the figure above. Logic network employs input signals at both gate and drain terminals. A selfchecking cmos full adder in double pass transistor. So the change in state of one of its input condition from logic 0 to logic 1 or logic 1 to logic 0. A general method in synthesis of passtransistor circuits. Design of low power multiplier with energy efficient full adder using.
Automated design for currentmode passtransistor logic. Cmos is the logic style of choice for the implementation of arbitrary combinational circuits if low voltage, low power, and small powerdelay products are of concern. Automated design for currentmode pass transistor logic blocks by matthew david pierson research project submitted to the department of electrical engineering and computer sciences, university of california at berkeley, in partial satisfaction of the requirements for the degree of master of science, plan ii. Among low power logic families, pass transistor logic ptl has great potential due to its ability to implement logic functions with a lower transistor count, smaller capacitance, and hence better performance, perhaps at the same. An advantage of passtransistor logic is its simplicity, but a disadvantage of srpl is similar to a disadvantage of standard cmos, namely the spikes on the powersupply that occur during switching.
Aziz abstruct behavior of basic and complex logic gates using complementary passtransistor. Disadvantage that output levels are always lower than the input level. Pass transistor logic if we integrate the expression describing cx we can solve for vx. Aziz abstruct behavior of basic and complex logic gates using complementary pass transistor. Nmos devices passes a strong 0 but a weak 1 while pmos transistors pass a. Since circuit is differential, complimentary inputs and outputs are available. Vlsi design pass transistor logicpass transistor logic. Pass transistor logic families there are two main pass transistor circuit styles. All exploit passtransistors to implement general logic functions nov2309 e4. Usha rani 3 1pg scholar, dept of vls system design, padmasri dr. 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. Transmissiongate digitalcmosdesign electronics tutorial.
Logic functions implemented using cmos transmission gates provide a moderate improvement in area and speed over logic gate implementations. In this paper, we present a selfchecking full adder based on the double pass transistor technology. The current drive of the transistor gatetosource voltage is reduce significantly as v. Transistors are used as switches to pass logic levels between nodes of a circuits, as. A cmos circuit generator using differential pass transistors. Adiabatic logic style is proving to be an attractive solution for low power digital design.
Cmos and pass transistor logic 2 institute of microelectronic systems nchannel transistors produce a logic 0 at the output when a logic 1. By evasion combinational logic circuits have no memory, timing, feedback loops contained by their design. Designing combinational logic circuits lesson learning outcome. The main goal is investigation of cmos and nmos approaches in pass transistor logic design. The voltage degradation caused by threshold drop can be.