ex7_1.m

射频电路设计：理论与应用：theory and applications 全部源代码

%
%   This program computes the small-signal impedance of 
%   a Si-based pn-junction diode
% 
%   Copyright (c) 1999 by P.Bretchko and R.Ludwig
%   "RF Circuit Design: Theory and Practice"
%

close all; % close all opened graphs
clear all; % clear all variables
figure;    % open new graph

% define problem parameters
TT=500e-12; % transit time
T0=300;     % temperature
Is0=5e-15;  % reverse saturation current at 300K
Rs=1.5;     % series resistance
nn=1.16;    % emission coefficient

% parameters needed to describe temperature behavior of 
% the band-gap energy in Si
alpha=7.02e-4; 
beta=1108;
Wg0=1.16;
pt=3;

% quiescent current
Iq=50e-3;

% frequency range 10MHz to 1GHz
f_min=10e6;  % lower limit
f_max=1e9;   % upper limit
N=300;       % number of points in the graph
f=f_min*((f_max/f_min).^((0:N)/N)); % compute frequency points on log scale

% temperatures for which analysis will be performed
T_points=[250 300 350 400];

% define physical constants
q=1.60218e-19; % electron charge
k=1.38066e-23; % Boltzmann's constant

colormap(lines);
color_map=colormap;
colormap('default');
legend_string=' ';

for n=1:length(T_points) 
   T=T_points(n);
   s=sprintf('T=%.f\n',T);
   Vt=k*T/q;
   
   Wg=Wg0-alpha*T^2/(beta+T);
   s=sprintf('%s   Wg(T)=%f\n',s,Wg);
   
   Is=Is0*(T/T0)^(pt/nn)*exp(-Wg/Vt*(1-T/T0));
   s=sprintf('%s   Is(T)=%e\n',s,Is);
   
   Vq=nn*Vt*log(1+Iq/Is);
   s=sprintf('%s   Vq(T)=%f\n',s,Vq);
   
   Rd=nn*Vt/Iq;
   s=sprintf('%s   Rd(T)=%f\n',s,Rd);
   
   Cd=Is*TT/nn/Vt*exp(Vq/nn/Vt);
   s=sprintf('%s   Cd(T)=%fpF\n',s,Cd/1e-12)
   
   Zc=1./(j*2*pi*f*Cd);
   
   Zin=Rs+Rd*Zc./(Rd+Zc);
   
   legend_string=strcat(legend_string,strcat(sprintf('T=%d',T),'{\circ}K')');
   semilogx(f/1e6,abs(Zin),'color',color_map(n,:));
   hold on;
end;   

axis([10 1000 1.5 2.4]);
legend(legend_string',1);
title('Frequency behavior of small-signal diode model');
xlabel('Frequency {\itf}, MHz');
ylabel('Impedance |Z|, \Omega');

%print -deps 'fig7_3.eps'