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 Author Topic: The Common Emitter Amplifier Circuit  (Read 79169 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
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 « Embed this message on: February 26, 2011, 01:41:00 pm » posted from:Taipei,T\'ai-pei,Taiwan

The following is a simulation for a Common Emitter Amplifier Circuit.

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The single stage common emitter amplifier circuit shown above uses what is commonly called "Voltage Divider Biasing". This type of biasing arrangement uses two resistors as a potential divider network and is commonly used in the design of bipolar transistor amplifier circuits. This method of biasing the transistor greatly Voltage Divider Network reduces the effects of varying Beta, ( β ) by holding the Base bias at a constant steady voltage level allowing for best stability. The quiescent Base voltage (Vb) is determined by the potential divider network formed by the two resistors, R1, R2 and the power supply voltage Vcc as shown with the current flowing through both resistors. Then the total resistance RT will be equal to R1 + R2 giving the current as i = Vcc/RT. The voltage level generated at the junction of resistors R1 and R2 holds the Base voltage (Vb) constant at a value below the supply voltage. Then the potential divider network used in the common emitter amplifier circuit divides the input signal in proportion to the resistance.
$V_B=\frac{R2}{R1+R2}Vcc$

Then $V_{RE}=V_B-V_{BE}$ (assume $V_{BE}=0.7V$)
$I_E=\frac{V_{BE}}{R_E}$
and
$I_E=I_C+I_B=(1+\beta) I_B$
So $I_C=\beta I_B=\frac{\beta}{1+\beta}I_E$
Finally, $V_{CE}=V_{cc}-V_{RL}-V_{RE}=$ $V_{cc}-I_C R_L-I_E R_E>V_{sat}$
($V_{sat}=0.2V$)

You are welcomed to check out similar applet at Common Emitter Transistor Amplifier
 electronic_CEamplifier.jpg (20.58 KB, 669x384 - viewed 3242 times.)  amp10.gif (28.22 KB, 504x553 - viewed 25030 times.) Logged
moraein
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 « Embed this message Reply #1 on: June 24, 2013, 07:45:33 pm » posted from:-,-,IRAN, ISLAMIC REPUBLIC OF

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2116.0

Hi i enjoyed with your simulation. very nice

I need Vcc=12 and Rl=10k .. can u do it for me ?
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Fu-Kwun Hwang
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 « Embed this message Reply #2 on: June 24, 2013, 11:10:58 pm » posted from:,,Satellite Provider

You can adjust parameters with sliders from the simulated circuit. Try it!
You need to adjust R1 and R2.
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jn300
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 « Embed this message Reply #3 on: December 28, 2013, 02:04:38 am » posted from:LONDON,ENGLAND,UNITED KINGDOM

Hi, I stumbled across this very useful simulation and it has helped me somewhat. I know this is slightly off topic to what you posted, but I was wondering how exactly do you determine individual component values for a common emitter circuit with only 2 variables given. vcc=12v and voltage gain being 10.

thank you
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Give me a standpoint and I will move the earth. ...Archimedes (287-212BC)