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Logic Design La bora lory Manuał

EXPERIMENT: 1    LOGIC GATES

A IM: To study and verify tlie truth tablc of logie gates

LEARNING OBJECTIYE:

♦    Idenlify various ICsand llieir specification.

COMPONTiNTS RIXH;IRMD:

» I ,ogic gales (IG) (rainer kii.

♦    ConnecLmg palch cliords.

♦    IC 7400, IC 7408, IC 7432, IC 7406, IC 7402, IC 7404, IC 7486 THEORY:

The basie logie gates are the building bloeks of morę complcx logie circuits. Hicse logie gates pc.rtbrm the basie Boolcan funetions, snch as AND, OR, NAND, NOR, Invcrsion, Excliisive-OR, Exclusivc-NOR. Fig. below shows the circnit symbol, Booleau funeriou, and truth. It is scen from tlie Fig tliat eaeh gate has one or two binaiy inpnts, A and B, and one binary output, C. The smali circle on tlie outpm of the Circuit symbols designates the logie complcmcnt. The AND, OR, NAND, and NOR gates can be cxtcndcd to havc moic. than two inpnts. A gate can be cxtcnded to have multiple inpnts if the binary operation it represents is commutative and associativc.

The.se basie logie gates anc impleinented as small-scale integrated circuits (SSICs) or as part of morę complcx medium scalę (MSI) or vcry largc-scalc (VLSI) integrated circuits. Digital IC gates are elassified not only by tlick logie operation, bnt also the speeifie logic-ciicnit family to wlńch tliey belong. Eaeh logie family has its own basie eleerronic circnit npon wliich morę compIex digital cirenits and funetions are developcd. Tlie following logie familics are the uiost hcciucntly used.

TTL ->Transistor-rransistor logie

ECL -^Emitter-conpled logie

MOS Metal-oxide semicondnetor

CMOS -^Complementary metal-oxidc semiconduetor

TTL and ECL are based npon bipoLar transistors. TTL has a wcll established popularity among logie familics. ECL is ttsed only in systems reqniring lugh-speed operation. MOS and CMOS, are based on field effect transistors. Tliey are widcly nsed in largo scalę integrated circuits bccause of their high component density and relatively Iow power consnmption. CMOS logie consnmes far less power than MOS logie. Tliere are varions commereial