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close this bookAmplifier Teaching Aid (GTZ, DED; 86 pages)
View the documentPreface
View the documentIntroduction
Open this folder and view contentsLesson 1 - Semiconductor Review
Open this folder and view contentsLesson 2 - Bipolar Transistor
Open this folder and view contentsBipolar Transistor II
View the documentFirst Evaluation
close this folderLesson 4 - Transistor Fundamentals
close this folderLesson Plan
View the documentThe load line
View the documentThe operating point
View the documentRecognizing saturation
View the documentThe transistor switch
View the documentWorksheet No. 4
Open this folder and view contentsLesson 5 - Transistor Biasing
Open this folder and view contentsLesson 6 - Transistor Biasing II
View the documentSecond Evaluation
Open this folder and view contentsLesson 7 - Small Signal Amplifier
Open this folder and view contentsLesson 8 - Small Signal Amplifier II
Open this folder and view contentsLesson 9 - Small Signal Amplifier III
Open this folder and view contentsLesson 10 - Large Signal Amplifier
View the documentThird Evaluation
 

The operating point

Every transistor circuit has a load line. If the base resistance is given you can also calculate the current and voltage for the operating point.

Ex: Calculate the operating point (Q-point)


Fig. 4-4: Base biased CE connection

IC = βdc * IB = 100 * 29μA = 2.9 mA

VCE = VCC - (IC * RC) = 15V - (2.9 mA * 3KΩ) = 6.3V

By plotting IC (2.9 mA) and VCE (6.3V), we get the operation point ----> Q-point (quiescent point).


Fig. 4 - 5: Collector curve with load line and Q - point

HO: Draw the load line and Q-point.


Fig. 4-6: base biased CE connection, β=50

Solution:

IC = IB * β = 2.15 mA

VCE = VCC - (RC * IC)= 5.7V


VCE (cut) = VCC = 3.0V

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