![]() ![]() There are two basic types of bipolar transistor construction, PNP and NPN, which basically describes the physical arrangement of the P-type and N-type semiconductor materials from which they are made. The word Transistor is an acronym, and is a combination of the words Transfer Varistor used to describe their mode of operation way back in their early days of development. Cut-off - the transistor is "fully-OFF" operating as a switch and Ic = 0 Saturation - the transistor is "fully-ON" operating as a switch and Ic = I(saturation)ģ. Active Region - the transistor operates as an amplifier and Ic = β.IbĢ. The fusion of these two diodes produces a three layer, two junction, three terminal device forming the basis of a Bipolar Junction Transistor, or BJT for short.ġ. If we now join together two individual signal diodes back-to-back, this will give us two PN-junctions connected together in series that share a common P or N terminal. Then bipolar transistors have the ability to operate within three different regions:ĭiodes made up from two pieces of semiconductor material, either silicon or germanium to form a simple PN-junction and we also learnt about their properties and characteristics. The transistor's ability to change between these two states enables it to have two basic functions: "switching" (digital electronics) or "amplification" (analogue electronics). Transistors are three terminal active devices made from different semiconductor materials that can act as either an insulator or a conductor by the application of a small signal voltage. The truth tables for each circuit proves that A.B = A+B. The complement of the product of variables is equal to the sum of their complementsįigure shows the logic circuit to represent the II law for two variables A and B. ![]() ![]() Since the net result of tables are same, this statements is proved for different inputs The truth table for the left and right side of the statement are represented in tables. These statements can be proved using the truth table given below.įigure shows the logic circuit to represent the 2nd law for two variables A and B. The complements of the sum of the variables are equal to the product of their complements. This statement can be proved using the truth table The Boolean expression for X-OR gate is Y=A, B+A. We know that the output of an X-OR gate will be at one level only if the inputs are at different levels. The output of an X-OR gate will stand in its defined one level if and only if all the inputs are at different levels. The output of a NOR gate will stand in its defined one level if and only if all the inputs are at zero level. It is the combination of OR gate and NOT gate. (It is nothing but the combination of AND gate and NOT gate) The output of an NAND gate will stand in the defined zero level if and only if all inputs are at one level. It inverts the input and so it is also called an inverter.The output of the NOT gate is zero if the input is 1 and the output is 1 if the input is 0. It has a single input and a single output. The output of an OR gate will stand in its defined one level if any one or more or all the inputs stand at their defined one level. The output of an AND gate will stand in its defined one level if and only if all the inputs stand at their defined one level. ![]() It is the tabulation, which represents all possible input and output conditions in logic levels. ![]()
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