SOP uses the idea of summation of minterms (product of inputs for which output is high)Īccording to the truth table given above, Sum of product expression and schematic for 3-input XOR gate is given below. Sum of products (SOP) and products of the sum (POS) are two methods in combinational logic. The truth table of “3” inputs XOR gate is given below.Ĭombinational logic is the logic of making a schematic with the help of basic logic gates. XOR gate can have more than two inputs but it has only one output. XOR gate gives HIGH state “1” only when there is an odd number of HIGH state “1” inputs. And can easily be implemented with NOR gates as shown in the figure below. It can be implemented into any Logic function.Īs we have discussed before POS (product of sum) expression can be easily implemented with NOR gates, so POS expression for XOR gate is given below SOP expression can be easily implemented with NAND gates. Min terms are the product of inputs for which output is HIGH state “1”. In this expression, we use the sum of Min terms. XOR operation can be achieved with a combination of different logic gates.īoolean expression of XOR is given below. XOR Gate From other Logic Gates: (Combinational Logic) When both inputs are LOW state “0”, again there will be no potential (voltage) at the gate of NMOSFET so it will never turn ON and Vdd will flow out to the inverter and inverts into LOW state “0” as output. Hence Vdd (HIGH state “1”) will flow to the inverter and inverts into LOW state “0” as output. if both are HIGH state “1” than the HIGH state will flow to the gate of NMOSFET but there will be no potential at its source so NMOSFET will switch OFF. And the LOW state will flow out to the inverter and inverts into HIGH state “1”. When both inputs are different, then the High state will flow to NMOSFET’s gate and the LOW state will flow to NMOSFET’s source to build up potential at its gate, which will switch it ON. The resistor between Diode Bridge and 1st MOSFET is used in parallel configuration because MOSFETs operates on Gate’s voltages, not current. 2 NMOSFETs are used 1st one for switching upon input logic and the 2nd one for Inverting output of 1st NMOSFET. In this schematic 4 diodes are used in a bridge configuration for sorting out input logic. XOR schematic using N-MOSFETs and diodes is given below. XOR Gate Using MOSFET and Diodesĭiscrete XOR gate can be made with MOSFETs and diodes. So again Vcc will flow through an inverter and invert into low state”0” as output. If it’s HIGH state “1” then the NPN will turn on but there will be no Logic 0 to flow through the emitter. So Vcc will flow out to the inverter phase and it will invert into Low state “0” as output. When the inputs are same, if it’s LOW state “0” then NPN will never turn on because there be no HIGH state input at its base. The LOW state “0” flow through the emitter to the base of the 2nd NPN transistor and inverts into Logic HIGH state “1” as output. When inputs are different, the high state flow to NPN transistor’s base and turn it ON. It only inverts the output of the first NPN transistor. And the second NPN transistor is nothing more than just an Inverter. The first transistor is used for switching upon the input logic given to it. And the Low state will always flow out to the emitter of NPN transistor. The diodes are used in a bridge configuration (Rectifier) to sort out the input logic into the positive level, means if there is a High state input it will always flow to the base of NPN to switch it on. 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. Schematic of XOR gate using Diodes and BJT (NPN transistor) is given below. International Electrotechnical Commission (IEC)/EUROPEANĬonstruction and Working Mechanism of XOR Gate XOR Gate Using BJT and Diodes There are 3 types of symbols used for XOR gate all over the world.Īmerican National Standards Institute (ANSI)/ MILITARY XOR Gate Logic Symbol, Boolean Expression & Truth Table XOR Gate Symbol XOR gate can have two or more than two inputs but it has only one output. XOR gate also known as Exclusive OR gate is “A logic gate which produces HIGH state ‘ 1’ only when there is an odd number of HIGH state ‘ 1’ inputs”.įor 2-input gate it can be interpreted as “when both of the inputs are different, then the output is HIGH state ‘1’ and when the inputs are same, then the output is LOW state ‘ 0’”. ![]() XOR Gate From other Logic Gates: (Combinational Logic).Construction and Working Mechanism of XOR Gate.XOR Gate Logic Symbol, Boolean Expression & Truth Table.What is Logic XOR or Exclusive-OR Gate?.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |