TransistorA devicethat acts either as a wireor a resistor, dependingon the voltage level of aninput signalSemiconductorMate-rial such as silicon that isneither a good conductornor insulator96Chapter 4Gates and CircuitsFigure 4.7Various representations of a three-input AND gateLogic Diagram SymbolBoolean ExpressionTruth Table1 0 – 6 7 6 CAB0000111100110011C01010101X00000001ABCX4.3Constructing GatesBefore we examine how gates are connected to form circuits, let’s examine,at an even more basic level, how a gate is constructed to control the flowof electricity.TransistorsA gate uses one or more transistors to establish how the input values mapto the output value. A transistoris a device that acts, depending on thevoltage level of an input signal, either as a wire that conducts electricity oras a resistor that blocks the flow of electricity. A transistor has no moving
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This note was uploaded on 01/13/2011 for the course CSE 1550 taught by Professor Marianakant during the Fall '10 term at York University.