Week #8: (10/26-30) Transistor Biasing & CE Amplifiers

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rjagodowski
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Joined: Fri Sep 04, 2015 6:59 pm

Week #8: (10/26-30) Transistor Biasing & CE Amplifiers

Post by rjagodowski »

This week we'll continue to discuss some of the circuits investigated in the Transistor Biasing Lab from Week #7.

A key point to keep in mind during this discussion: The current gain parameter, beta (also known as hFE), generally has a wide range of values within a specific part number. For example the 2N2222 transistor may have a beta range between 50 to 300. One goal of the various biasing circuits we are discussing is to stabilized the bias point, known as the Q-point, with respect to variations in beta.

We will begin analyzing a Common Emitter Voltage Divider Biased NPN transistor amplifier for A.C. operation. The example we will work through is the one presented in our Week #8 lab experiment. Check out this link for information about the r-parameter Transistor Model.

We will also discuss some of the parameters for the 2N2222A & 2N3904 transistor spec sheets, specifically those dealing with beta (hFE on the sheet). Here are the pdfs for these two transistors:
2N2222A-Datasheet.PDF
(119.67 KiB) Downloaded 32 times
2N3904_Datasheet.pdf
(188.88 KiB) Downloaded 30 times

Here are some screenshot of the WhiteBoard presentation from the 2018 Fall course:
EET-200_BJT_CE_ClassA_2018-1030_01.JPG
EET-200_BJT_CE_ClassA_2018-1030_01.JPG (1.77 MiB) Viewed 249 times
EET-200_BJT_CE_ClassA_2018-1030-02.JPG
EET-200_BJT_CE_ClassA_2018-1030-02.JPG (1.65 MiB) Viewed 249 times
EET-200_BJT_CE_ClassA_ACModel_2018-1101-01.JPG
EET-200_BJT_CE_ClassA_ACModel_2018-1101-01.JPG (1.88 MiB) Viewed 249 times
EET-200_BJT_CE_InputImpedance_2018-1101-02.JPG
EET-200_BJT_CE_InputImpedance_2018-1101-02.JPG (1.55 MiB) Viewed 249 times
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