武漢大學(xué)射頻電路第八次作業(yè)

1、電子與通信工程 王世杰 第八次作業(yè)1、一晶體管的S參量如下：f=750MHz：s11=0.114-j*0.551，s12=0.044+j*0.029，s21=-4.608+j*7.312，s22=0.490-j*0.449;f=1000M：s11=-0.058-j*0.452，s12=0.054+j*0.022，s21=-2.642+j*6.641，s22=0.379-j*0.424; 畫出晶體管在兩個(gè)頻率下的輸出及輸入穩(wěn)定圓并計(jì)算各自，K,D值。解：當(dāng)f=750MHz，編程畫出輸出及輸入穩(wěn)定圓，并計(jì)算，K,D的值。程序如下：close all; % close all opened grap

2、hsclear all; % clear all variables s11=0.114-1j*0.551;s12=0.044+1j*0.029;s21=-4.608+1j*7.312;s22=0.490-1j*0.449; s_param=s11,s12;s21,s22; % convert the S-parameters into matrix notationsmith_chart; % create a Smith Chartinput_stability(s_param, r); % plot input stability circle in red colorsmith_cha

3、rt; % create a Smith Chartoutput_stability(s_param, b);% plot output stability circle in blue color d,k,u=K_factor(s_param);輸入輸出穩(wěn)定圓如下：|D|=|S11S22-S12S21|=0.5561；可知在該頻率下晶體管不是絕對(duì)穩(wěn)定的當(dāng)f=1000MHz時(shí)，輸入輸出穩(wěn)定圓如下圖：|D|=|S11S22-S12S21|=0.4535；可知在該1000MHz頻率下晶體管不是絕對(duì)穩(wěn)定的2、已知晶體管的S參量在傳輸線特性阻抗為50測(cè)得為S110. 57170，S120.06669，

4、S212.9771，S220.46-26。其輸入端與VS30，ZS50的電壓源連接，輸出端口接Zin40的天線。求放大器的入射功率Pinc，電源的資用功率PA，負(fù)載的吸收功率PL，轉(zhuǎn)換功率增益GT，資用功率增益GA及功率增益G。解：編程計(jì)算放大器的入射功率，電源的資用功率，負(fù)載的吸收功率，轉(zhuǎn)換功率增益，資用功率增益及功率增益：close all; % close all opened graphsclear all; % clear all variablesZ0=50;s11=0.57*exp(j*(170)/180*pi);s12=0.066*exp(j*(69)/180*pi);s21=

5、2.97*exp(j*(71)/180*pi);s22=0.46*exp(j*(-26)/180*pi);Vs=3;Zs=50;Zl=40;GamaS=(Zs-Z0)/(Zs+Z0);GamaL=(Zl-Z0)/(Zl+Z0);D=s11*s22-s12*s21;GamaIn=s11-GamaL*D/(1-s22*GamaL);GamaOut=s22-GamaS*D/(1-s11*GamaS);Pinc=1/2*(Z0/(Zs+Z0)*abs(Vs)2/abs(1-GamaIn*GamaS)2Pa=1/2*(Z0/(Zs+Z0)*abs(Vs)2/(1-abs(GamaS*GamaS)2)Gt

6、=(1-abs(GamaL)2)*abs(s21)2*(1-abs(GamaS)2)/(abs(1-GamaL*GamaOut)2*abs(1-s11*GamaS)2)Ga=abs(s21)2*(1-abs(GamaS)2)/(1-abs(GamaOut)2)*abs(1-s11*GamaS)2)G=(1-abs(GamaL)2)*abs(s21)2/(1-abs(GamaIn)2)*abs(1-s22*GamaL)2)Pl=Pa*Gt計(jì)算結(jié)果如下： 3. 已知晶體管在2.0+0.xxxGHz處的S參量為S110.6525, S120.119, S215.0110, S220.65-36。用輸

7、入不匹配輸出匹配方案設(shè)計(jì)放大器，在圓圖上分別畫出增益為最大可能增益的90，80%，50的等資用功率增益圓。若源阻抗及負(fù)載阻抗均為50歐，對(duì)于增益是50的情況設(shè)計(jì)具體的匹配網(wǎng)絡(luò)。解：計(jì)算K和D值為：K=1.0007，D=0.9725,由此可以看出該晶體管絕對(duì)穩(wěn)定。計(jì)算可得該放大器的最大增益=43.8，化為分貝表示為：= 16.4147 dB,畫出資用功率分別為15.9572 dB(90%)，15.4456 dB(80%)，13.4044 dB(50%)的等資用功率圓如圖所示：取 ，則：，得到 L=out*=0.838+j0.485。根據(jù)和設(shè)計(jì)匹配電路,頻率為2.137GHz：輸入端：并聯(lián)2.3n

8、H的電感，然后串聯(lián)8.0H的電感輸出端：并聯(lián)586.4pF的電容，然后串聯(lián)29.3nH的電感function k,delta = K_factor(s_param) % Usage: k,delta = K_factor(s_param)% Purpose: returns k factor for a given s-parameter matrix% if k1 and delta1 then circuit is uncoditionally stable% otherwise circuit might be unstable s11=s_param(1,1);s12=s_param(

9、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);endfunction = ZiYongGain(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=

10、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)./(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*

11、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*(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(dg

12、a)-0.1,imag(dga)+rga+0.05,strcat(bf,sprintf(G=%g dB,G_goal_dB);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 = 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*log10(G2)G3=G_Tmax*0.5G3_dB=10*log10(G3) Zi