DiodeCircuits

LectureOutline

•  Introduc2ontoDiode•  PowerSupply•  Rec2fica2on– HalfWaveRec2fier– FullWaveRec2fier

•  CenterTapeTransformer

•  BridgeRec2fier– Rec2fierwithacapaci2veFilter

Ques2on

Ques2onWhatisadiode?

Ques2onsAnswerSemiconductorunidirec2onalswitch

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 4

Figure3.1Theidealdiode:(a)diodecircuitsymbol;(b)i–v characteris2c;(c)equivalentcircuitinthereversedirec2on;(d)equivalentcircuitintheforwarddirec2on.

Ques2on

•  Whatdoyouthinkoftheapplica2onofdiode?

Ques2on

•  Answer– Applica2on

•  NE344Courserequirement•  Powersupplyasrec2fiers•  Reverseblockagecurrent•  Clippercircuit•  ClamperCircuit

• 

PowerSupplyBlockDiagram

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 7

Blockdiagramofadcpowersupply.

Rec2fierCircuits

•  Rec2fierCircuits– Halfwaverec2fier– Fullwaverec2fier

•  UsingCentertapeTransformer

•  BridgeRec2fier

HalfWaverec2fiers

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 9

Figure3.25(a)Half‐waverec2fier.(b)Equivalentcircuitofthehalf‐waverec2fierwiththediodereplacedwithitsbaWery‐plus‐resistancemodel.(c)Transfercharacteris2coftherec2fiercircuit.(d)Inputandoutputwaveforms,assumingthatrD!R.

FullWaveRec2fiers

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 10

Figure3.26Full‐waverec2fieru2lizingatransformerwithacenter‐tappedsecondarywinding:(a)circuit;(b)transfercharacteris2cassumingaconstant‐voltage‐dropmodelforthediodes;(c)inputandoutputwaveforms.

BridgeRec2fier

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 11

Figure3.27Thebridgerec2fier:(a)circuit;(b)inputandoutputwaveforms.

Rec2fierwithCapacitorFilter

Figure3.28(a)Asimplecircuitusedtoillustratetheeffectofafiltercapacitor.(b)Inputandoutputwaveformsassuminganidealdiode.Notethatthecircuitprovidesadcvoltageequaltothepeakoftheinputsinewave.Thecircuitisthereforeknownasapeakrec2fierorapeakdetector.

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 13

Figure3.29Voltageandcurrentwaveformsinthepeakrec2fiercircuitwithCR@T.Thediodeisassumedideal.

MicroelectronicCircuits‐FiJhEdi2onSedra/Smith 14

Figure3.30Waveformsinthefull‐wavepeakrec2fier.