# 2 Stage BJT Amplifier (Design/Analysis)

#### bratva

Joined Apr 20, 2016
1
Hi all.
(I've been self-studying Electronics as a hobby.
This website is extremely helpful. Thank you!)

I require help designing and analyzing the following using the parameters given below:

Stage 1 - (Potential Divider Biased) Common Emitter: 2mA ≤ Ic(q) ≤ 15mA
Av (CE) = 2 ≤ |Av| ≤ 6 (with RL connected)

Stage 2 - (Potential Divider Biased) Common Collector: 5mA ≤ Ic(q) ≤ 10mA
Av (CC) = 1 (approximately)

*Also, RL = RC
*Both Stages must be mid-point biased
*Power Supply = +15V

#### Bordodynov

Joined May 20, 2015
2,745
You need to know the input impedance. For example> 1k.
You also need to know the size of the load (the number). Conditions Rc = RL is not rational. The emitter follower reduces the output resistance that allows the use of low-resistance load. Those. the collector resistance of the first stage may be significantly greater than the load. Simply put the input impedance of the emitter follower in the (beta + 1) times its total load. If this is not homework, I can give an example of the construction of the circuit without the base divider resistors (with a minimum of elements and overall feedback DC). Give only the numerical values of which I wrote at the beginning.

Last edited:

#### MrAl

Joined Jun 17, 2014
7,891
Hi all.
(I've been self-studying Electronics as a hobby.
This website is extremely helpful. Thank you!)

I require help designing and analyzing the following using the parameters given below:

Stage 1 - (Potential Divider Biased) Common Emitter: 2mA ≤ Ic(q) ≤ 15mA
Av (CE) = 2 ≤ |Av| ≤ 6 (with RL connected)

Stage 2 - (Potential Divider Biased) Common Collector: 5mA ≤ Ic(q) ≤ 10mA
Av (CC) = 1 (approximately)

*Also, RL = RC
*Both Stages must be mid-point biased
*Power Supply = +15V

Hello and welcome,

I am happy to hear about people who are new or even old to electronics but want to learn more. I'll help all i can and i am sure there are lots of other people here who will too.

To start, did you ever design a SINGLE stage transistor amplifier? That would be a prerequisite. So to start this task, you would first design the first stage which is the emitter follower. Do you know how to begin with that?

Also, what kind of math have you done in the past?
Algebra, trig, geometry, etc.