Cse 370 spring 1999 combinational implementation 35 abc 0 1 2 3 4 5 6 7 1 0 1 0 0 0 1 1 s2 8. Half adder and full adder circuits using nand gates. Most logic gates have two inputs and one output and are based on boolean algebra. Nor flash memory technology overview page 3 nor vs. A 2input nand gate with both inputs tied together, or one input tied low, is an inverter and performs not. The number of transistors required to implement an ninput logic gate is 2n. Combinational logic implementation z twolevel logic y implementations of twolevel logic y nand nor z multilevel logic y factored forms y andorinvert gates z time behavior y gate delays y hazards z regular logic y multiplexers y decoders y palplas y roms cs 150 sringp 0012 combinational implementionta 2 implementations of twolevel logic. How to implement a boolean function and verifying its logic using only nandnor logic gates. Build the nand gate circuit from prelab on ltspice. To build an inverter, you can use nand or nor gates as follows. Finally, he must create an implementation using only nand gates or only nor gates. The circuit of sr flip flop using nor gates is shown in below figure. May 24, 2014 logic gates and, or, not, nor, nand, xor, xnor gates.
The first part is an and gate and second part is a dot after it represents a not gate. Degenerate and term nand nand example nand nand example nor gates nor implementation useful transformations graphical transformations general twolevel implementations general. To implement a boolean function using nor gate, there are basically three step. Nand and nor are universal gates university of iowa. How to draw a nand gate using only nor gates quora. This article relies largely or entirely on a single source.
Pdf implementation of not, nand and nor gate mujtaba. Random sequential easeofuse hardware easy easy complicated full system. And thus, it can be aptly termed as universal gate. The circuit output should follow the same pattern as in the truth table for different input combinations. First one is the functional completeness each boolean. B b a when both a and b are high, output is low when either a or b is low, output is high 6. The circuit diagram is similar to that of not gate made by using only nand gate. Thus, the nand gate implementation is a less expensive and faster implementation. A logic gate is a building block of a digital circuit. The realization of noninverting boolean functiona such as and or, or xor in a single stage is not possible, and requires the addition of an extra inverter stage. This means that if either of these things happen, i.
So, what were going to do is start by pondering why this class of problem should be posed in the first place. In terms of hardware efficiency, how does the nand implementation compare to the aoi implementation. A basic cmos structure of any 2input logic gate can be drawn as follows. In the aoi implementation, identify and replace every and,or, and inverter gate with its nor equivalent. Convert the products and terms and the final sum or to nands. Multilevel nand nor implementation of logical functions a. When both the set and reset inputs are low, then the output remains in previous state i. Depending on the type of logic gate being used and the. The same pattern will continue even if for more than 3 inputs. An inverter can be made from a nand gate by connecting all of the inputs together and creating, a single input as shown below. Sr flip flop can also be designed by cross coupling of two nor gates. Two and multilevel logic implementation tajana simunic rosing 2 sources.
The boolean expression for nand gate is, the boolean expression for nor gate is, this is a great advantage because a user will have. Oct 28, 2015 as mentioned earlier, a nand gate is one of the universal gates and can be used to implement any logic design. Kime nand and nor implementation nand gates nand gates cont. Cmos technology and logic gates mit opencourseware. If starting from a logic expression, implement the design with aoi logic. To achieve this, first the logic function has to be written in sum of product sop. How to implement a function using just nand or nor logic. How the logic circuits can be designed using these gates. Furthermore, demorgans theorem tells you that, with inverted inputs, a nand gate becomes functionally an or gate. The conversion from an andornot gate design to one that uses only nand gates is straightforward. Apr 12, 2017 a burglar alarm when the switch is closed one input of the nand gate is low. As it happens, if you have a collection of nand gates you are able to all of these.
Combinational logic implementation implementations of two level logic. Components and design techniques for digital systems. Discuss how nand gates can be used to perform the and, or and not logic operations. Multilevel nand nor implementation of logical functions. Implementing logic functions using only nand or nor gates. Twolevel digital circuit implementations using universal gates only. In case of nand gate, 3 pmos will be connected in parallel and 3 nmos will be connected in series, and other way around in case of 3 input nor gate. A nand gate implementation requires addition of an inverter not gate at the output. Twolevel logic using nand gates twolevel logic using. Jan 04, 2020 the above diagram is of a not gate made by using a nor gate. Next, were going to look at this students particular poser in more detail, taking it to an initial andor solution. Now we will look at the operation of nor gates and nand gates as universal gates nand gate as universal gate.
Run a dc sweep of the nand circuit by sweeping vin2 from 0v to 10v with increments of 1v. Nand nor implementation boolean algebra digital electronics. Nor function implementation nand gates can implement a simplified sumofproducts form. Add a nand gate for any product with only a single literal. Nor flash was first introduced by intel in 1988, revolutionizing a market that was then dominated by eprom and eeprom devices. Implementing twolevel logic using nor gate requires the boolean expression to be in product of sum pos form. In practice, this is advantageous since nand and nor gates are economical and easier to fabricate and are the basic gates used in all ic digital logic families. For nand in the purely logical sense, see logical nand. Universal gate nand i will demonstrate the basic function of the nand gate. Nandand and andnor are equivalent and both perform the andorinvert aoi function. Nand and and and nor are equivalent and both perform the andorinvert aoi function.
Cmos vlsi is thedigital implementation technology of choice for the foreseeable future next 1020 years excellent energy versus delay characteristics high density of wires and transistors monolithic manufacturing of devices and interconnect, cheap. What is logic gate and, or, xor, not, nand, nor and xnor. Nand memory is used the most in high capacity data storage, because of its fast write cycles, large data capacity 8mb128mb and long life span of over 10 times the life span of nor memory. The nand gate is a universal gate because it can be used to produce the not operation, the and operation, the or operation, and the nor operation. Any logic function can be implemented using nand gates. Discuss how nor gates can be used to perform the and, or and not logic operations. And or nand xor xnor gate implementation and applications.
The procedure is write the boolean expression in sop form. If we want to perform n bit addition, then n number of 1 bit full adders should be used in the. When the ldr is in the light the other input is low. Aug 04, 2015 a basic cmos structure of any 2input logic gate can be drawn as follows. Pdf on transformation of a logical circuit to a circuit with nand. So, from the above discussion, it is clear that all the three basic gates and, or, not can be made by only using nor gate. In theory, the highest density nand will be at least twice the density of nor, for the same process technology and chip size. So it is clear that during the operation of nand gate, the inputs are first going through and gate and after that, the output gets reversed, and we. Nand gates are available with three inputs 74ls10 and four inputs 74ls20. How a logic circuit implemented with aoi logic gates can be reimplemented using only nand gates. A universal gate is a gate which can implement any boolean function without need to use any other gate type. Access method random on code area, sequential on data area. At any given moment, every terminal is in one of the two binary conditions false high or true low. Jun 02, 2015 sr flip flop can also be designed by cross coupling of two nor gates.
The circuit of full adder using only nand gates is shown below. In product of sum form, 1st level of the gate is or gate and 2nd level of the gate is and gate. Now lets understand how this circuit will behave like a nand gate. Degenerate and term nandnand example nandnand example nor gates nor implementation useful transformations graphical transformations general twolevel. The above drawn circuit is a 2input cmos nand gate. As mentioned earlier, a nand gate is one of the universal gates and can be used to implement any logic design. Nand or nor nand and nor memory have many different advantages and disadvantages, making one or the other more fit for a certain purpose. Any function can be implemented using only nand or only nor gates. This article is about nand logic in the sense of building other logic gates using just nand gates. The analysis of nand nor logic diagrams to determine the output functions in andor logic is also made easier by the method.
That using a single gate type, in this case nand, will reduce the number of integrated circuits ic required to implement a. Sr flip flop design with nor gate and nand gate flip flops. The nand only implementation allows us to only manipulate and worry about one kind of gate. Logic gates and, or, not, nor, nand, xor, xnor gates.
How a nand gate can be used to replace an and gate, an or gate, or an inverter gate. Nor implementation the nor operation is the dual of the nand operation the nor gate is another universal gate to implement any boolean function easy for or. Several kinds of digital logic circuits are the basic elements that form the building blocks for such complex digital system as the. A scheme for implementing multilevel nand nor network of a logical function is presented. Cmos vlsi is thedigital implementation technology of choice for. Nand 91sr012048l 2 introduction two main technologies dominate the nonvolatile flash memory market today. Logic gate actually the term logic is applied to digital circuits used to implement logic functions.
The nand gate has the property of functional completeness, which it shares with the nor gate. Nand flash density for any given lithography process, the density of the nand flash memory array will always be higher than nor flash. Nand and nor gates how circuit elements are implemented. Nor flash was first introduced by intel in 1988, revolutionizing a market that was.
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