Difference between revisions of "Symbolsk løsning av nodeligninger med Matlab"

From ift
m
m
Line 2: Line 2:
 
<pre>
 
<pre>
 
% Using Kirchoff's current law (KCL) on a source follower configuration
 
% Using Kirchoff's current law (KCL) on a source follower configuration
% to find Vout as a function of Vin
+
% to find Vo as a function of Vin
 
% Only Cgd is considered (Zc)
 
% Only Cgd is considered (Zc)
 
% Kjetil Ullaland
 
% Kjetil Ullaland
  
ligning1='(Vout-Vgs)/Zc+gm*Vgs+Vout/Rl=0';
+
syms s Vin Vo Vgs Zc gm Rl Rs R
ligning2='(Vgs-Vout)/Zc+(Vgs-Vin)/Rs=0';
 
ligning1=subs(ligning1,'1/(j*w*C)','Zc');
 
ligning2=subs(ligning2,'1/(j*w*C)','Zc');
 
pretty(ligning1);
 
pretty(ligning2);
 
  
 +
eq1='(Vo-Vgs)/(R+Zc)+gm*Vgs+Vo/Rl=0';
 +
eq2='(Vgs-Vo)/(R+Zc)+(Vgs-Vin)/Rs=0';
 +
eq1=subs(eq1,Zc,'1/(s*C)');
 +
eq2=subs(eq2,Zc,'1/(s*C)');
 +
disp('KCL for circuit node 1:');
 +
pretty(eq1);
 +
disp('KCL for circuit doc prettynode 2:');
 +
pretty(eq2);
  
 
disp('Solve for Vgs');
 
disp('Solve for Vgs');
vgs_solved=solve(ligning2,'Vgs');
+
vgs_solved=solve(eq2,Vgs);
 
pretty(simplify(vgs_solved));
 
pretty(simplify(vgs_solved));
  
disp('Solve for Vout(vin)');
+
disp('Solve for Vo(vin)');
ligning3=subs(ligning1,vgs_solved,'Vgs');
+
eq3=subs(eq1,Vgs,vgs_solved);
Vout_solved=solve(ligning3,'Vout');
+
Vo_solved=solve(eq3,Vo);
pretty(simplify(Vout_solved))
+
pretty(simplify(Vo_solved/Vin))
 
</pre>
 
</pre>
  

Revision as of 09:46, 13 September 2016

Using Kirchoff's current law (KCL) on a source follower configuration to find Vout as a function of Vin

% Using Kirchoff's current law (KCL) on a source follower configuration
% to find Vo as a function of Vin
% Only Cgd is considered (Zc)
% Kjetil Ullaland

syms s Vin Vo Vgs Zc gm Rl Rs R

eq1='(Vo-Vgs)/(R+Zc)+gm*Vgs+Vo/Rl=0';
eq2='(Vgs-Vo)/(R+Zc)+(Vgs-Vin)/Rs=0';
eq1=subs(eq1,Zc,'1/(s*C)');
eq2=subs(eq2,Zc,'1/(s*C)');
disp('KCL for circuit node 1:');
pretty(eq1);
disp('KCL for circuit doc prettynode 2:');
pretty(eq2);

disp('Solve for Vgs');
vgs_solved=solve(eq2,Vgs);
pretty(simplify(vgs_solved));

disp('Solve for Vo(vin)');
eq3=subs(eq1,Vgs,vgs_solved);
Vo_solved=solve(eq3,Vo);
pretty(simplify(Vo_solved/Vin))

Using Kirchoff's current law (KCL) on single transistor stage, fig. 9.18 to find Vo as a function of Is

% Using Kirchoff's current law (KCL) on single transistor stage, fig. 9.18
% to find Vo as a function of Is
% Kjetil Ullaland, 2015

syms Vo V1 s gm R1 R2 C C1 C2 Is Zc Rz;

%% With feedforward capacitor
eq1=sym('(Vo-V1)/Zc+gm*V1+Vo/R2+Vo*s*C2=0');
eq2=sym('(V1-Vo)/Zc+V1*s*C1+V1/R1+Is=0');
eq1=subs(eq1,Zc,'1/(s*C)');
eq2=subs(eq2,Zc,'1/(s*C)');

solV1=solve(eq2,V1);
eq3=subs(eq1,V1,solV1);
SolVo=simplify(solve(eq3,[Vo]));
disp('With capacitor only in feedforward loop');
pretty(simplify(SolVo/Is));

%% With series resistor and capacitor in feedforward loop
eq1=sym('(Vo-V1)/(Zc+Rz)+gm*V1+Vo/R2+Vo*s*C2=0');
eq2=sym('(V1-Vo)/(Zc+Rz)+V1*s*C1+V1/R1+Is=0');
eq1=subs(eq1,Zc,'1/(s*C)');
eq2=subs(eq2,Zc,'1/(s*C)');

solV1=solve(eq2,V1);
eq3=simplify(subs(eq1,V1,solV1));
SolVo=solve(eq3,[Vo]);
disp('With series resistor and capacitor in feedforward loop');
pretty(simplify(SolVo/Is));