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| author | priyanka | 2015-06-24 15:03:17 +0530 |
|---|---|---|
| committer | priyanka | 2015-06-24 15:03:17 +0530 |
| commit | b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b (patch) | |
| tree | ab291cffc65280e58ac82470ba63fbcca7805165 /1757/CH14/EX14.11/EX14_11.sce | |
| download | Scilab-TBC-Uploads-b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b.tar.gz Scilab-TBC-Uploads-b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b.tar.bz2 Scilab-TBC-Uploads-b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b.zip | |
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Diffstat (limited to '1757/CH14/EX14.11/EX14_11.sce')
| -rwxr-xr-x | 1757/CH14/EX14.11/EX14_11.sce | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/1757/CH14/EX14.11/EX14_11.sce b/1757/CH14/EX14.11/EX14_11.sce new file mode 100755 index 000000000..a1bb07abf --- /dev/null +++ b/1757/CH14/EX14.11/EX14_11.sce @@ -0,0 +1,65 @@ +// Example14.11 // Design a video amplifier of IC 1550 circuit
+clc;
+clear;
+close;
+Vcc = 12 ; // V
+Av = -10 ;
+Vagc = 0 ; // at bandwidth of 20 MHz
+hfe = 50 ; // forward emitter parameter
+rbb = 25 ; // ohm // base resistor
+Cs = 1*10^-12 ; // F // source capacitor
+Cl = 1*10^-12 ; // F // load capacitor
+Ie1 = 1*10^-3 ; // A // emitter current of Q1
+f = 1000*10^6 ; // Hz
+Vt = 52*10^-3 ;
+Vt1 = 0.026 ;
+
+// When Vagc =0 the transistor Q2 is cut-off and the collector current of transistor Q2 flow through the transistor Q3
+// i.e Ic1=Ie1=Ie3
+Ie3 = 1*10^-3 ; // A // emitter current of Q3
+Ic1 = 1*10^-3 ; // A // collector current of the transistor Q1
+
+// it indicates that the emitter current of Q2 is zero Ie2 = 0 then the emitter resistor of Q2 is infinite
+re2 = %inf ;
+
+// emitter resistor of Q3
+re3 = (Vt/Ie1);
+disp('The emitter resistor of Q3 is = '+string(re3)+' ohm ');
+
+// the trans conductance of transistor is
+gm = (Ie1/Vt1);
+disp('The trans conductance of transistor is = '+string(gm)+' A/V ');
+
+// the base emitter resistor rbe
+rbe = (hfe/gm);
+disp('The base emitter resistor rbe is = '+string(rbe)+' ohm ');
+
+// the emitter capacitor Ce
+Ce = (gm/(2*%pi*f));
+disp('The emitter capacitor is = '+string(Ce)+' F ');
+
+// the voltage gain of video amplifier is
+// Av = (Vo/Vin) ;
+// Av = -((alpha3*gm)/(rbb*re3)*((1/rbb)+(1/rbe)+sCe)*((1/re2)+(1/re3)+sC3)*((1/Rl)+(s(Cs+Cl))))
+ // At Avgc = 0 i.e s=0 in the above Av equation
+alpha3 = 1 ;
+s = 0 ;
+Av =-10 ;
+Rl = -((alpha3*gm)/((rbb*re3)*(((1/rbb)+(1/rbe))*((1/re2)+(1/re3))*(Av))));
+Rl = (1/Rl);
+disp('The value of resistance RL is = '+string(Rl)+' ohm ');
+
+// there are three poles present in the transfer function of video amplifier each pole generate one 3-db frequency
+Rl = 265
+fa = 1/(2*%pi*Rl*(Cs));
+disp('The pole frequency fa is = '+string(fa)+' Hz ');
+
+
+fb = 1/(2*%pi*Ce*((rbb*rbe)/(rbb+rbe)));
+disp('The pole frequency fb is = '+string(fb)+' Hz ');
+
+fc = 1/(2*%pi*Cs*re3);
+disp('The pole frequency fc is = '+string(fc)+' Hz ');
+
+disp(' Hence fa is a dominant pole frequency ');
+
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