武汉大学射频电路第九次作业(共4页)

1、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S110.6525, S120.119, S215.0110, S220.65-36。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=43.8，化为分贝表示为：= 16.4147 dB,画出资用功率分别为15.9572 dB，15.445

2、6 dB，13.4044 dB的等资用功率圆如图所示：取 ，则：，得到 L=out*=0.88+0.4 i。根据和设计匹配电路：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: returns k factor for a given s-parameter matrix% if k>1 and delta<1 then circuit is un

3、coditionally stable% otherwise circuit might be unstable s11=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+delta2)/(2*abs(s12.*s21);u=(1-abs(s11)2)/(abs(s22-s11*conj(D)+abs(s12)*abs(s21);Endfunction Gamma_S,Gamma_out = ZiYongGai

4、n(s_param,G_goal)%UNTITLED11 Summary of this function goes here% Detailed explanation goes here hold on;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);% find constant operating power gain circlesdelta=det(s_param);K=(1-abs(s11)2-abs(s22)2+abs(delta)2).

5、/(2*abs(s12.*s21);ga=G_goal/abs(s21)2; % normalized the operating power gain% find the center of the constant operating power gain circledga=ga*conj(s11-delta*conj(s22)/(1+ga*(abs(s11)2-abs(delta)2); % find the radius of the circle rga1=sqrt(1-2*K*ga*abs(s12*s21)+ga2*abs(s12*s21)2);rga=rga1/abs(1+ga

6、*(abs(s11)2-abs(delta)2); % plot a circle in the Smith Charta=(0:360)/180*pi;hold on;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=%g dB',G_goal_dB);plot(real(dga)+rga*cos(105),imag(dga)+

7、rga*sin(105),'bo');text(real(dga)+rga*cos(105)-0.05,imag(dga)+rga*sin(105)-0.07,'bfGamma_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);endclose all;clear all;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) % check stabilityG_Tmax=abs(s21)*(K-sqrt(K2-1)/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*log1