From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

---
 135/CH7/EX7.5/EX5.sce | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100755 135/CH7/EX7.5/EX5.sce

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+// Example 7.5: Operating point
+clc, clear
+VP=-5; // in volts
+IDSS=12e-3; // in amperes
+// From Fig. 7.34(a)
+VDD=18; // in volts
+R1=400; // in kilo-ohms
+R2=90; // in kilo-ohms
+RD=2e3; // in ohms
+RS=2e3; // in ohms
+// Applying Thevnin's theorem to obtain simplified circuit in Fig. 7.34(b)
+VGG=VDD*R2/(R1+R2); // in volts
+// Plotting transfer characteristics
+VGS=[VGG:-0.01:VP]; // Gate source voltage in volts
+// Using Shockley's equation
+ID=IDSS*(1-VGS/VP)^2; // Drain current in amperes
+ID=ID*1e3; // Drain current in mili-amperes
+plot2d(VGS,ID,rect=[-5,0,3,12]);
+xtitle("Transfer Characteristics","VGS (V)","ID (mA)");
+// Plotting bias line
+// From the KVL for the gate-loop
+ID=(-VGS+VGG)/RS; // Source current in amperes
+ID=ID*1e3; // Source current in mili-amperes
+plot(VGS,ID,"RED");
+// Intersection of transfer curve with the bias curve
+// Putting VGS = VGG-ID*RS in Shockley's equation and solving, we get
+// ID^2*RS^2 + (2*RS*VP - 2*VGG*RS - VP^2/IDSS)*ID + (VGG-VP)^2
+// Solving the equation
+p_eq = poly([(VGG-VP)^2 (2*RS*VP-2*VGG*RS-VP^2/IDSS) RS^2],"x","coeff");
+p_roots= roots(p_eq);
+IDQ=p_roots(1); // in amperes
+// Writing the KVL for the drain source loop
+VDSQ=VDD-IDQ*(RD+RS); // in volts
+IDQ=IDQ*1e3; // in mili-amperes
+disp(VDSQ,"VDSQ (V) =");
+disp(IDQ,"IDQ (mA) =");
\ No newline at end of file
-- 
cgit