ECE492 Section 2 Notes

From eddynetweb's cesspit
Jump to navigation Jump to search

Welcome! Notes for Spring 2022 Electronic Circuits course. Will make this more pretty as things evolve.

My goal is to make Electronic Circuits so easily digestible, you could teach a middle schooler. We'll see if this works.


Hey how are you. I will insert something here later. :)

Section 2.1

We'll begin by covering a Bi-polar Junction Transistor, also known as BJT.

What is it exactly? Well, it's a transistor.

  • It is a 3 terminal devices.
  • It is a unsymmetrical device.
  • It amplifies the signal.

There are two types of BJTs:

  • NPN, in which...
  • PNP, in which...

Now we'll cover (B) Common Emitter Current gain:

  • 50 < B < 200

...and (Alpha) Common Base Current Gain:

V-I Characteristics of Transistors:

  • AAAA

NPN Transistor Example:

  • Cut Off: Both junction are reverse biased.
  • Saturation: Both junction are forward biased.
  • Active: One junction is forward biased, another one is reverse biased.

Understanding cut off regions for NPN transistors:

  • Cut off region (open switch - both junctions one reverse biased)
  • Saturation region (closed switch)
  • Active region (amplification - one junction forward biased another is reverse biased)
  • Breakdown region (Damaged - acts like open circuit essentially)

How do you know when one of these three (or four counting breakdown) apply?

  • Voltage
    • VE < VB < Vc
    • VE < VB > Vc
    • VE > VB < Vc
    • VE > VB > Vc
  • NPN
    • Active
    • Saturation
    • Cut off
    • Reverse active
  • PNP
    • Reverse active
    • Cut off
    • Saturation
    • Active

Understanding common emitter (CE) configuration

  • Consider the following configurations...

Consider the following example:

  • We'll assume that VB is equal to 0 (since it is grounded).
  • Start solving the example by assuming active mode of operation.
  • In active mode of operation
    • BBE = 0.7 (NPN), BCE >= 0.3V
    • BEB = 0.7 (PNP), BEB >= 0.3V

Therefore, VEB = 0.7V = VE - VB such that VB = 0

Header 2

It sometimes allow current, and sometimes it doesn't.

Assignment 1.1

We'll take this and plug it into to find x2: