Lecture 4 Two-Port Circuits and Power Gain

《Lecture 4 Two-Port Circuits and Power Gain》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、EECS142Lecture4:Two-PortCircuitsandPowerGainProf.AliM.NiknejadUniversityofCalifornia,BerkeleyCopyrightc2005byAliM.NiknejadA.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.1/23–p.1/23AGenericAmplifierYS+·¸y11y12vsYLy21y22−Considerthegenerictwo-portamplifiershownabove.Notethat

2、anytwo-portlinearandtime-invariantcircuitcanbedescribedinthisway.Wecanuseanytwo-portparameterset,includingadmittanceparametersY,impedanceparametersZ,orhybridorinverse-hybridparametersHorG.A.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.2/23–p.2/23ChoosingTwo-PortParameter

3、sFeedbackYSYout+vsAmpYL−YinThechoiceofparametersetisusuallydeterminedbyconvenience.Forinstance,ifshuntfeedbackisapplied,Yparametersaremostconvenient,whereasseriesfeedbackfavorsZparameters.Othercombinationsofshunt/seriescanbeeasilydescribedbyHorG.ABCDparametersareusefulforcascadingtwo

4、-ports.A.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.3/23–p.3/23YParametersWe’llprimarilyusetheYparameters!!!i1y11y12v1=i2y21y22v2Butinfactthechoicedependslargelyonconvenience.Oftentheformoffeedbackdeterminesthebestchoice.All2-portparametersareequivalent.Manyoftheresult

5、sthatwederivecarryintermsofY-parameterscanbeappliedtoothertwo-portparameters(inputimpedance,outputimpedance,gain,etc).A.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.4/23–p.4/23AdmittanceParametersNoticethaty11istheshortcircuitinputadmittancei1y11=v1v2=0Thesamecanbesaidof

6、y22.Theforwardtransconductanceisdescribedbyy21i2y21=v1v2=0whereasthereversetransconductanceisdescribedbyy12.Ifatwo-portamplifierisunilateral,theny12=0A.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.5/23–p.5/23Hybrid-ΠAdmittanceParametersCµYπYo+YµRinCinvingmvinroCo−Let’scom

7、putetheYparametersforthecommonhybrid-ΠmodelYi2µy11=yπ+yµ++v1YπYogmvinv2=0−−y21=gmyµA.M.NiknejadUniversityofCalifornia,BerkeleyEECS142Lecture4p.6/23–p.6/23AdmittanceParameters(cont)i1Yµy22=yo+yµ++v1=0YπYogmvinv2−−y12=yµNotethatthehybrid-πmodelisunilateralifyµ=sCµ=0.Thereforeit’sunilat

8、eralatDC.y21