hi everyone, this is my first post/thread and i hope you all don't mind me jumping right in to asking a homework help questions.
basically i'm performing a lab experiment where we are to design a common emitter amplifier using a 2n2222 bjt as in this diagram i hastily drew up linked below:
http://mygumballs.com/images/CommonEmitter.jpg
the specifications are minimal: a Vcc of 10V, a collector current of 1 mA, and a gain of -14. other than that, we must design the amplifier by choosing the resistor values to obtain this. my question, essentially, is how do i do this?
now i generally have a good idea of what i need to do, but my professor is so demanding and so unhelpful, that i know there will be bad consequences if i don't get it completely correct. so here's what i know:
i have on that figure a beta value of 400. i'm not sure if this is correct, but i recall this is the value we determined when the class viewed the characterstics of a 2n2222 on the cure tracer. regardless, if possible, it would be nice to make my calculations beta independant. though i seriously doubt this is possible.
using the ac analysis technique, i found the following equation for hte gains:
Av = (-Rc*Beta)/(Beta/gm + (1+Beta)*Reac)
which will give me the relation:
Rc = 364 + 14*Reac
at this point, i don't know how to progress to find these two resistor values without just pulling on of their values out of the air arbitrarily. if i do have to choose values for one of these resistors, is there any criteria i should use?
after reading some threads here about similar problems, i've read about choosing a q point in which either Vce or Vc should be half of what their saturation equivalents would be. but because of the ambiguity between those two, i'm not sure what rule to use.
and furthermore, after possibly finding the values of Rc and Re, my professor insists that there is a sure way to find exact values for R1 and R2, a process that DEFINATELY eludes me.
i really need help with this. i've been finding it extremely difficult to find someone who can help me with transistor analysis and if someone here can show me a step by step process of how to design this amplifier, i know i can use it to finally understand how these things work in general. i will be thuroughly thankful if you can help me and i'll definately be a regular subscriber to this forum. thanks!
basically i'm performing a lab experiment where we are to design a common emitter amplifier using a 2n2222 bjt as in this diagram i hastily drew up linked below:
http://mygumballs.com/images/CommonEmitter.jpg
the specifications are minimal: a Vcc of 10V, a collector current of 1 mA, and a gain of -14. other than that, we must design the amplifier by choosing the resistor values to obtain this. my question, essentially, is how do i do this?
now i generally have a good idea of what i need to do, but my professor is so demanding and so unhelpful, that i know there will be bad consequences if i don't get it completely correct. so here's what i know:
i have on that figure a beta value of 400. i'm not sure if this is correct, but i recall this is the value we determined when the class viewed the characterstics of a 2n2222 on the cure tracer. regardless, if possible, it would be nice to make my calculations beta independant. though i seriously doubt this is possible.
using the ac analysis technique, i found the following equation for hte gains:
Av = (-Rc*Beta)/(Beta/gm + (1+Beta)*Reac)
which will give me the relation:
Rc = 364 + 14*Reac
at this point, i don't know how to progress to find these two resistor values without just pulling on of their values out of the air arbitrarily. if i do have to choose values for one of these resistors, is there any criteria i should use?
after reading some threads here about similar problems, i've read about choosing a q point in which either Vce or Vc should be half of what their saturation equivalents would be. but because of the ambiguity between those two, i'm not sure what rule to use.
and furthermore, after possibly finding the values of Rc and Re, my professor insists that there is a sure way to find exact values for R1 and R2, a process that DEFINATELY eludes me.
i really need help with this. i've been finding it extremely difficult to find someone who can help me with transistor analysis and if someone here can show me a step by step process of how to design this amplifier, i know i can use it to finally understand how these things work in general. i will be thuroughly thankful if you can help me and i'll definately be a regular subscriber to this forum. thanks!