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Transistor diagram for a nand gate12/26/2023 ![]() ![]() ![]() We can realize a logic gate by 2 methods. ![]() This cause to occur more delay, as the time required for the input to reach output becomes high.Īnother reason for opting NAND gate is its low “logic effort”. As the occupied area is high, the capacitance associated with the NOR gate is also high. The area occupied by NOR gate is more than that of the area occupied by NAND gate. Why we prefer NAND gate over NOR, to design basic logic circuits? Let’s see why these are preferred and how we can design other gates by using NAND gate. Mostly, we prefer NAND gates over NOR gates for designing the other basic logic gates. This is because, This gate can function as any of the basic logic gates by just making some changes at its input side. At the end of the clock pulses in the above, the output is at high level as one of the inputs is low. When both inputs are high, then the output of the NAND gate will be LOW and when either of the inputs is low, then the output goes to HIGH level. If we apply 2 different clock signals as the inputs of NAND gate X and Y, then the output of the NAND gate is shown below (X, Y are inputs and Z is output) The resistors connected at the input side are of each 10K ohms. the emitter of the first transistor is connected to the collector of the second transistor and the emitter of the second transistor is grounded. The 2 transistors are connected in series i.e. The output is collected across the collector of the transistor and the resistor. The supply voltage of +6 V is passed to the collector of first transistor, through a resistor. NAND gate can be designed by using transistors also.To design a 2 –input transistor NAND gate, we connect two resistors to bases of the two transistors. It will become HIGH if both the inputs are High.īack to top 2 – Input Transistor NAND Gate Nand Gate Truth Tableįrom the truth table, it can be observed that NAND gate output will be high if any of its input is at low state. Where, bar “ ̅“represents the reverse operation. Mathematical expression for NAND gate operation is given as Z =(X.Y) ̅. The circuit and logic symbol for NAND gate is given below. 0, then no current flows through the transistor, so it will become OFF. In the same way, if we apply the low voltage supply to both the diodes (logic low) i.e. This makes the transistor to be in ON state, so the voltage at the output Vce (Sat) will be 0. At this condition, transistor Q1 is capable for driving the supply voltage from the resistor. Since the diodes don’t conduct, they both will be in OFF state. +5 V (logic HIGH), then the 2 diodes will be reverse biased. When the inputs of both diodes of NAND gate are connected to a high voltage level i.e. The inputs to the NAND gate is applied through the diodes and these diodes are connected to BJT. The equivalent circuit of NAND Gate using diodes and transistors is shown below. It has 2 inputs X, Y and single output, Z. One should know the fact that AND gate is constructed from the AND gate. The outputs of AND gate and NAND gates are inverse to each other. ![]() It has the capability to perform the operations of 3 logic gates such as OR, AND gate and NOT gate. NAND gate is the combination of AND gate and NOT gate. NAND gate Logic Symbol and equivalent circuit Commonly available TTL and CMOS logic NAND gate IC.Basic Logic Gates using only NAND Gates.Why we prefer NAND gate over NOR, to design basic logic circuits?.NAND gate Logic Symbol and equivalent circuit. ![]()
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