We will continue our discussion of bipolar transistor biasing as presented last week
here. We'll discuss some of the circuits investigated in the Transistor Biasing Lab from Week #8 and the pdf is posted
here in the Registered Users Only area.
Here's a pic of the white board showing the analysis we did in class of the Voltage Divider Bias circuit of Fig. 5-3:
- EET-200_Notes_2015-1105.jpg (292.99 KiB) Viewed 1472 times
Key topic 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 discussed some of the parameters for the 2N2222A transistor's spec sheet, specifically those dealing with beta (hFE on the sheet). Here is the pdf for the 2N2222 transistor in the TO-92 package: