Week #10: (11/7-11) Transistor Biasing, dB & Gain

Post Reply
rjagodowski
Posts: 2370
Joined: Fri Sep 04, 2015 6:59 pm

Week #10: (11/7-11) Transistor Biasing, dB & Gain

Post by rjagodowski »

This week we'll finish the A.C. Analysis and A.C. Model of the Common Emitter Amplifier we began last Thursday. Here is a link explaining the r-parameter Model of a bipoloar junction transistor.

Our next transistor lab on Common Collector Amplifiers is found here in the Registered Users Only area.

Some summary links:

Common Emitter Voltage Divider Bias Summary, pay special attention to the graph showing the sinusoidal variations of iB, iC 7 VCE.

Here's a good review & practice of Voltage Divider biased transistors from Wisc-online.com . Calculating D.C. Values for a Resistor Bias Class A amplifier, from Wisc-Online.


We'll discuss Gain calculations (below) then continue with the following:

Class A, Class B and Class AB amplifiers, Cross-over Distortion.

We'll spend a bit of time discussing the Output Characteristic Curves (scroll down a bit).

Amplifier Distortion

Here's a link that will let you hear the effects of distortion common waveshapes. http://www.falstad.com/mathphysics.html. Scroll down to the "Signal Processing" simulations, then open the "Fourier Series Applet". These simulation do require a Java-enabled web browser. Set the signal to a sinusoid, set the frequency & volume to a comfortable combination, click the "Sound Option" and listen as you "Clip" the wave. You can also manually distort the wave using your mouse. Note that ANY change (distortion) to the basic sine wave results in higher frequencies being added to the signal. These frequencies are called "Harmonics". An ideal amplifier will amplify the input signal with the least addition of harmonics. Often times you will see a "Total Harmonic Distortion" specification in an amplifier spec sheet. This relates the total amount of distortion which may be added to a signal by that amplifier.

Efficiency, Gain and dBs from AllAboutCircuits.com and Amplifier Gains from Electronic-Tutorials.ws (scroll down a bit).

Decibels, Gain, Power & Voltage from Wisc-online.

A handy summary of dB Conversions.

Amplifier Summary from Electronics-Tutorials.ws.


Wikipedia on Differential Amplifiers, Common & Differential Mode Operation.


Here are some practice problems on Gain Calculations. We'll eventually cover this entire sheet, but for now look at problems 1, 2 & 3.
Gain Calculation Problems v15.1.pdf
(65.29 KiB) Downloaded 159 times
Post Reply

Return to “EET-200 Lecture”