Cmos circuits for either function can be can built from just 6 transistors, but those circuits have some undesirable features. How to make a not gate using xor gate, or gate and 2 and. In this paper we proposed a novel structure which can be used for simultaneous implementation of optical xor and xnor logic gates. But the reader may also see the simpler, more general, logic gate representations. Experiment 2 basic logic gates implementation using breadboards. I mean intuitively, to me, i should get this one if i do it step by. In fact, most gates are implemented in solidstate ttl chips transistortransistor logic. A new 5transistor xorxnor circuit based on the pass transistor logic.
Any combinational logic can be implemented using a universal gate. For example, the first embedded system, the apollo guidance computer, was built exclusively from nor gates, about 5,600 in total for the later versions. According to many sources for instance wikipedia, its possible to obtain xor gate using 4 nand gates. Schematic of xor gate using diodes and bjt npn transistor is given below. Inverters and transmission gates are particularly useful for building transmission gate exclusive or xor and xnor logic. Alloptical multiple logic gates with xor, nor, or, and nand functions using parallel soamzi structures. An or gate equivalent can also be constructed using only nand gates, by putting two shorted equivalent to not nand gates each at the input of a third nand gate as shown in figure 4. In this paper by utilizing a new concept for designing logic gates based on mobile, we have presented new threeinput xor and xnor gates which. Mosfet gate operation gate capacitance gatesubstrate parallel plate capacitor.
Now to make a nor gate, using 4 mosfets just like the nand gate. The proposed structure was designed using a nonlinear photonic crystal ring resonator. Optical xor and x nor gates can be used for designing optical adders and optical comparators, respectively. Hi, through some searching and guessing with logisim i was able to see how to build a xor gate from only nor gates. Pdf alloptical multiple logic gates with xor, nor, or, and. Export eps export svg export svgz description a xor gate using nand gates. More typically, xor and xnor logic gates are built from three nand gates and two inverters, and so take 16 transistors. If both inputs are false 0low or both are true, a false output results. But its inadvisable as each xor gate will use atleast 6 to 8 mosfets. Using ltspice and irsim, here are the simulations of the logical operation of the gate for all 4 possible input.
The old techinterview forum xor gate using nand gates. Use truth tables for a nor gate to design an xor gate. Oct 08, 2010 hi, through some searching and guessing with logisim i was able to see how to build a xor gate from only nor gates. Here pull down network consists of all ntype transistors. Rather than allowing the output to be high when either one or both of the inputs are high, an xor gate has a high output only when only one input is high. A nand gate and a nor gate are called as universal gate.
I know the answer but how to get the gate diagram from the formula. Today, contrary to popular belief, integrated circuits are not constructed exclusively from a single type of gate. Circuit diagram of a nand gate using transistors and resistors in the circuit diagram above you will notice that output is always high except when both transistors are biased. For example, the, apollo guidance computer, was built exclusively from nor gates, about 5,600 in total for the later versions. An or gate equivalent can also be constructed using only nand gates, by putting two shorted equivalent to not nand gates each at the input of a third nand gate as. The standard ntype domino xor gate dxn as shown in figure 5. How would you get from only nor gates to building a circuit equivalent to a 2 input xor. Logic gates and, or, not, nor, nand, xor, xnor gates.
A rectifier could function like a xor function, but you have to keep track of all four situations. Now we can implement the circuit of xnor gate using nor gates. To get acquainted with different standard integrated circuits ics. Digital logic basics 21 implementation using nand gates. I am not very good at ascii art so i couldnt provide gates and bubbles. This video shows the nand gate and then the nor gate implemented on the home made cpld board. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20 computer science cornell university see. Q implement 2 variable xnor gate using nor only in minimum number of gates.
Several kinds of digital logic circuits are the basic elements that form the building blocks for such complex digital system as the. Pdf a new 5transistor xorxnor circuit based on the pass. Add not gate to the output of xor gate as shown in the image above. Now i need a not gate that has to be done only with the above mentioned gates. Logic gates not, or, and, nor, nand, xor, xnor gate, pdf. The figure shows two ways in which a nor gate can be used as an inverter not gate. When the two signals being compared are completely inphase, i. Xor gate is a basic logic gate in digital system that use the combination of and and or gates. One nor input pin is connected to the input signal a while all other input. For example, a single cd4007 can be used to make three inverters, an inverter plus two transmission gates, or other complex logic functions such as nand and nor gates. Apr 19, 2018 step by step procedure to implement exor xor gate by using only nand gates.
This file is licensed under the creative commons attributionshare alike 3. I cannot follow the algebraic example and would like to have detailed steps filled in as i cannot match up rules i know to the example. As a nor gate is equivalent to an or gate leading to not gate. Xorgate is a basic logic gate in digital system that use the combination of and and or gates. An example im working on is a xor gate built from nor gates, i already know how to wire it to a breadboard and it works, but i dont understand how to derive the configuration i attached a. How to derive xor from only nor gates physics forums. All nor input pins connect to the input signal a gives an output a. May 24, 2014 logic gates and, or, not, nor, nand, xor, xnor gates. The cd4007 is a very versatile ic with many uses as we saw in the previous lab activity1.
Aug 21, 2017 i prepared xnor gate using 4 nor gates and xor gate using 5 nor gate using 2 methods. Universal gates in digital electonics nand and nor. This construction entails a propagation delay three times that of a single nor gate and uses five gates. If we look at the truth table carefully we will find that the first three results are totally satisfying the process of binary addition but in the last input sequence i. Logic gates objective to get acquainted with the analogdigital training system. A cd4011b was used as an example of a nand gate ic. The clock signal divides the circuit operation into two operating phases, precharge and.
The dtl nand gate combines the dtl inverter with a simple dioderesistor logic. Like nand gates, nor gates are socalled universal gates that can be combined to form any other kind of logic gate. Digital circuitsnor logic wikibooks, open books for an. If it used nand gates i would of completed this problem already haha. So yes you are correct, it does function like a xor gate except youll have the diode voltage drop included rectifier. To derive the rules of boolean algebra related to an xor gate, i take the basic point of standard rules and substitutes the standard rules with an xor gate function.
However, when i try to do so step by step by replacing all gates using nand and cancelling two nand gates that are in cascade, i always end up getting 5. Nand and nor gates are called universal gate because you can construct any gate using nand gate or nor gate. Exclusiveor gate tutorial the exclusiveor logic function is a very useful circuit that can be used in many different types of computational circuits in the previous tutorials, we saw that by using the three principal gates, the and gate, the or gate and the not gate, we can build many other types of logic gate functions, such as a nand gate. Xor and and form a universal set of gates which i completed a proof of. Xor gate sometimes eor, or exor and pronounced as exclusive or is a digital logic gate that gives a true 1 or high output when the number of true inputs is odd.
Also, i will be assuming open drain gate designs so that we can use wired anding. To study and verify the truth tables of and, or, not, nand, nor. The importance of nand nand gates are considered to be the universal gate, because any other gate can be synthesized eve engels, 2006 slide 22 of 20 using nand. Thanks for the a2a yes, we can make other gates using just xor gate. Note that we already know that a not gate is equivalent to a nor gate with its inputs joined.
This is the large expression i came up with to express the schematic. A phase detector for square wave signals can be made from an exclusiveor xor logic gate. The clock signal divides the circuit operation into two operating phases, precharge and evaluation phase. Logic gate actually the term logic is applied to digital circuits used to implement logic functions. See supplementary power point file for animated cmos process flow. Exclusiveor gate tutorial with exor gate truth table. Lab6 designing nand, nor, and xor gates for use to. But still i cannot see how to transform the equation into the xor expression i expect. U can also implement a combinationla logic or basic gates using muxes. Nov 16, 2014 use truth tables for a nor gate to design an xor gate. Inputs and outputs of logic gates can occur only in two levels.
The restrictions for this problem are that the nor gate only excepts 2inputs and it must only use and and xor gates. It produces a 1 output only when even number of 1 is present at the input. Im trying to understand how to design simple gates using boolean algebra and im getting nowhere. It produces a 1 output only when its two inputs are equal i. The logic gate nor takes two or more input and works as per the following truth table. Switch circuit diagram of nor gate edit xor and xnor gates there exist two other basic logic gates xor exclusiveorand xnor exclusivenor. Exor gate xor and exnor gate xnor using nand gates. Otherwise either if both the inputs are false 0 or if both are true 1 then a false output 0 is received as a resultant. Xor logic gate using other logic gate and other logic gate. It is implemented as an exclusive or gate in which a true output 1 is received as the resultant output if one of the inputs to the logic gate is true 1. I would like to know what the process for deriving this would look like. Step by step procedure to implement exorxor gate by using only nand gates. The jed file is for configuring the home made cpld board.
Pdf a new 5transistor xorxnor circuit based on the. Implementing comb logic using muxes is useful in the cases of fpgas, if you are having a shortage of comb gates. Wire and operate logic gates such as and, or, not, nand, nor, xor. This construction has a propagation delay 3 times that of a single gate and uses 5 gates. Hence we need only 4 nor gates to implement xnor gate and we require 5 nor gates to implement xor gate with 5 th nor gate used as inverter and placed in front of 4 th nor gate. Im just starting boolean algebra and am following an example given in the text that shows the configuration of nor gates to create an xor. A nor gate is a universal gate, meaning that any other gate can be represented as a combination of nor gates.
Tamas kovacs thursday, august 19, 2004 i want it plant marwa aly monday, october 11, 2004 please provide us the logic circuit for implementing xor gate using nand and nor gate. All structured data from the file and property namespaces is available under the creative commons cc0 license. Cmos logic gates nor schematic x x y gx,y x y x x y. In which we have used two npn transistors, 4 diodes and the resistor between diode bridge and npn is used in series configuration because bjts operates on input current, not input voltages. To understand formulation of boolean function and truth table for logic circuits. The dynamic node gives xnor gate logic and output node gives xor gate logic. Help me understand xor gate with diode logic electrical. Dec 6 general 1726 views no comments on xor logic gate using other logic gate the xor gate is a digital logic gate. We can create and, or and not gate using the nor gate. I prepared xnor gate using 4 nor gates and xor gate using 5 nor gate using 2 methods. To make it easy, just copy and change the schematic file used for the nand gate, to avoid tediuos work.
A nor gate is a logic gate which gives a positive output only when both inputs are negative. A nor gate is a logic gate which gives a positive output only when both inputs are negative like nand gates, nor gates are socalled universal gates that can be combined to form any other kind of logic gate. The main application of the exclusive or gate is in the operation of half and full adder. Exclusiveor xor digital logic gate electrical technology. Like nand gates, nor gates are socalled universal gates that can be. Universal logic gate nor logic gate dyclassroom have. Pdf realization of alloptical xor, nor, and nand gates in. A novel proposal for alloptical xorxnor gate using a. Oct 27, 2009 files are available under licenses specified on their description page.