Laboratory Manual - King Fahd University of Petroleum and Minerals
Laboratory Manual - King Fahd University of Petroleum and Minerals
Laboratory Manual - King Fahd University of Petroleum and Minerals
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KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS<br />
DEPARTMENT OF ELECTRICAL ENGINEERING<br />
Electronic Circuits II – EE303<br />
Experiment # 1<br />
Frequency Response <strong>of</strong> the Common Source Amplifier<br />
OBJECTIVES<br />
1. To measure the frequency response <strong>of</strong> common source (CS) amplifier.<br />
2. To determine the useful b<strong>and</strong>width <strong>of</strong> the CS amplifier by finding the midb<strong>and</strong><br />
frequency gain (A M ), the low <strong>and</strong> high 3dB corner frequencies.<br />
3. To investigate the effect <strong>of</strong> load resistance on the frequency response.<br />
4. To study the effect <strong>of</strong> the bypass capacitor on the frequency response.<br />
A typical CS amplifier is shown in Figure 1.<br />
BACKGROUND<br />
+V DD =5V<br />
100k<br />
R 2<br />
R D<br />
4.3k<br />
C 2<br />
v o<br />
R sig<br />
C 1<br />
C S<br />
R L<br />
1k<br />
v sig<br />
0.15<br />
300k<br />
R 1<br />
R S<br />
2N4351<br />
0.15<br />
1.3k 10<br />
100k<br />
15<br />
Figure 1: A typical common source amplifier<br />
As you have studied in your lectures small signal ac analysis can be used to shown that:<br />
1. The midb<strong>and</strong> frequency gain (A M ) is given by:<br />
vo RG<br />
'<br />
AM<br />
gmRL<br />
(1)<br />
v R R<br />
sig sig G<br />
Where RG<br />
R1||<br />
R2<br />
<strong>and</strong> R L<br />
RL || RD<br />
2. The low <strong>and</strong> high -3dB pole frequencies can be estimated as:<br />
3 1 1 1 1<br />
wL<br />
<br />
i1<br />
R 1<br />
iSCi C1( RSig RG ) C2( RL RD<br />
)<br />
CS( RS<br />
|| )<br />
g<br />
m<br />
(2)
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