武汉大学射频电路第九次作业

第九次作业电子与通信工程王世杰20142821201881.已知晶体管在2.0+0.188GHz处的S参量为S11＝0.65∠－25,S12＝0.11∠9,S21＝5.0∠110,S22＝0.65∠-36。用输入不匹配输出匹配方案设计放大器，在圆图上分别画出增益为最大可能增益的90％，80%，50％的等资用功率增益圆。若源阻抗及负载阻抗均为50欧，对于增益是50％的情况设计具体的匹配网络。解：计算K和D值为：K=1.0007，D=0.9725,由此可以看出该晶体管绝对稳定。计算可得该放大器的最大增益maxTG=43.8，化为分贝表示为：maxTG=16.4147dB,画出资用功率分别为15.9572dB，15.4456dB，13.4044dB的等资用功率圆如图所示：取0.20410.9152sj，则：122122110.88-0.4i1SoutSSSSS，得到ГL=Гout*=0.88+0.4i。根据s和L设计匹配电路：输入端：并联4.1nH的电感，然后串联11.8nH的电感输出端：并联523.5pF的电容，然后串联30.7nH的电感function[k,delta,u]=K_factor(s_param)%Usage:[k,delta]=K_factor(s_param)%%Purpose:returnskfactorforagivens-parametermatrix%ifk1anddelta1thencircuitisuncoditionallystable%otherwisecircuitmightbeunstables11=s_param(1,1);s12=s_param(1,2);s21=s_param(2,1);s22=s_param(2,2);D=det(s_param);delta=abs(D);k=(1-abs(s11)^2-abs(s22)^2+delta^2)/(2*abs(s12.*s21));u=(1-abs(s11)^2)/(abs(s22-s11*conj(D))+abs(s12)*abs(s21));Endfunction[Gamma_S,Gamma_out]=ZiYongGain(s_param,G_goal)%UNTITLED11Summaryofthisfunctiongoeshere%Detailedexplanationgoeshereholdon;s11=s_param(1,1);s12=s_param(1,2);s21=s_param(2,1);s22=s_param(2,2);G_goal_dB=10*log10(G_goal);%findconstantoperatingpowergaincirclesdelta=det(s_param);K=(1-abs(s11)^2-abs(s22)^2+abs(delta)^2)./(2*abs(s12.*s21));ga=G_goal/abs(s21)^2;%normalizedtheoperatingpowergain%findthecenteroftheconstantoperatingpowergaincircledga=ga*conj(s11-delta*conj(s22))/(1+ga*(abs(s11)^2-abs(delta)^2));%findtheradiusofthecirclerga1=sqrt(1-2*K*ga*abs(s12*s21)+ga^2*abs(s12*s21)^2);rga=rga1/abs(1+ga*(abs(s11)^2-abs(delta)^2));%plotacircleintheSmithCharta=(0:360)/180*pi;holdon;plot(real(dga)+rga*cos(a),imag(dga)+rga*sin(a),'r','linewidth',2);text(real(dga)-0.1,imag(dga)+rga+0.05,strcat('\bf',sprintf('G=%gdB',G_goal_dB)));plot(real(dga)+rga*cos(105),imag(dga)+rga*sin(105),'bo');text(real(dga)+rga*cos(105)-0.05,imag(dga)+rga*sin(105)-0.07,'\bf\Gamma_S');Gamma_S=(real(dga)+rga*cos(105))+1j*(imag(dga)+rga*sin(105));Gamma_out=s22+s12*s21*Gamma_S/(1-s11*Gamma_S);endcloseall;clearall;smith_chart;s11=0.65*exp(1j*(-25)*pi/180);s12=0.11*exp(1j*9*pi/180);s21=5*exp(1j*110*pi/180);s22=0.65*exp(1j*(-36)*pi/180);s_param=[s11,s12;s21,s22];[K,delta,u]=K_factor(s_param)%checkstabilityG_Tmax=abs(s21)*(K-sqrt(K^2-1))/abs(s12)G_Tmax_dB=10*log10(G_Tmax)G1=G_Tmax*0.9G1_dB=10*log10(G1)G2=G_Tmax*0.8G2_dB=10*log10(G2)G3=G_Tmax*0.5G3_dB=10*log10(G3)ZiYongGain(s_param,G1);ZiYongGain(s_param,G2);[Gamma_s,Gamma_out]=ZiYongGain(s_param,G3)