场效应管放大电路 课件.ppt

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1、Chapter4Field-EffectTransistorAmplifiers4.1Field-EffectTransistors4.2FETAmplifiers第四章场效应管放大电路4.1Field-EffectTransistorsTwotypes:junctionfield-effecttransistor(JFET)andthemetal-oxide-semiconductorFET(MOSFET)。4.1.1JunctionField-EffectTransistors(结型场效应管)1.StructureandOpera

2、tion(结构及工作）1)BasicStructureandSymbol(基本结构及符号)4.1场效应管StructureofN-channelJFET(N沟道结型场效应管结构)SymbolofN-channelJFET(N沟道结型场效应管符号)(c)SymbolofP-channelJFET(P沟道结型场效应管符号)4.1场效应管gateDepletionlayerdrainsource2)Operation4.1场效应管4.1场效应管2．Characteristics(特性)1)TransferCharacteristic(转移

3、特性)TherelationbetweeniDanduGSforacertainuDS(在uDS一定时,漏极电流iD与栅源电压uGS之间的关系)。4.1场效应管TransferCharacteristicofN-channelJFETUP2)DrainCharacteristic(漏极输出特性)ForUP≤uGS≤0,4.1场效应管DrainCharacteristicofN-channelJFET4.1场效应管4.1.2Metal-oxide-semiconductorFETs(绝缘栅型场效应管)1.Enhancement-mode

4、MOSFET(增强型绝缘栅场效应管)1)StructureandSymbol(结构及符号)4.1场效应管StructureofN-channelenhancement-modeMOSFETSymbolofN-channelenhancement-modeMOSFETSymbolofP-channelenhancement-modeMOSFET2)Characteristics(特性)（1）TransferCharacteristicofN-channelEnchancement-modeMOSFETwhenuGS≥UT,（2）Drai

5、nCharacteristicofN-channelEnchancement-modeMOSFET4.1场效应管（a）TransferCharacteristic（b）DrainCharacteristic4.1场效应管UTStructureofN-channeldepletion-modeMOSFETSymbolofN-channeldepletion-modeMOSFETSymbolofP-channeldepletion-modeMOSFET4.1场效应管2.Depletion-modeMOSFETN-channeldepletio

6、n-modeMOSFET（a）Transfercharacteristic（b）DraincharacteristicWhenuGS≥UP,4.1场效应管Up4.2FETAmplifiersThecommon-sourceamplifierThecommon-drainamplifierThecommon-gateamplifier4.2场效应管放大器Thecommon-sourceJFETamplifierSmall-signalJFETparametersDefinetransconductanceas:4.2场效应管放大器Calc

7、ulategmalgebraicallyandgraphically4.2场效应管放大器Small-signalmodelofJFET4.2场效应管放大器Acommon-sourceJFETamplifierwithfixedbias4.2场效应管放大器Thesmall-signalequivalentcircuit4.2场效应管放大器ExampleTheJFETintheamplifiercircuithasIDSS=12mA,VP=-4V,andrd=100k.1.FindthequiescentvaluesofIDandVDS.2.F

8、indgm.3.Drawtheequivalentcircuit.4.Findthevoltagegain.4.2场效应管放大器Solution:4.2场效应管放大器Bias-s