JFET and BJT amplifier tutorials

Hi there,
I been out of the forum for a long time for some reasons but let me cut all that... I was trying to make a FM transmitter but I needed to revise my BJT and oscillator practicals for that, which I did moderately, I made a tutorial for those who are interested, so see the attachment.Having said all that, for JFET I have tried to derive that shockely equation in this tutorial which needed to be verified by some experienced member So I'll be grateful if any one do that for me, I refered Sedra- Smith book for that in which equation for E-MOSFET is derived, this one in attachment is for JFET.



EDIT: see appendix of attachment for that equation

c36041254 said:

Hi there,
I been out of the forum for a long time for some reasons but let me cut all that... I was trying to make a FM transmitter but I needed to revise my BJT and oscillator practicals for that, which I did moderately, I made a tutorial for those who are interested, so see the attachment.Having said all that, for JFET I have tried to derive that shockely equation in this tutorial which needed to be verified by some experienced member So I'll be grateful if any one do that for me, I refered Sedra- Smith book for that in which equation for E-MOSFET is derived, this one in attachment is for JFET.



EDIT: see appendix of attachment for that equation

Click to expand...

I used to use JFETs for amplifiers but rarely do anymore. First of all, you just don't get the gain that you do with a BJT and second, they are square law devices which means there is a small linearity problem there. But they have there application. I think if I was concerned with NOT loading a very sensitive circuit and settling for any amplification at all, then yes a JFET can be very useful in buffering type application and they are very quiet devices. So if you do not attempt to achieve more than a few DB of gain thereby operating on a small portion of the load line, you will have the best overall replication of a signal. Just, not much gain.

Nice tutorial. Thanks. But what do I do if I dont have an output characteristic chart?

Gain is a number (the ouput voltage divided by the input voltage), and is not measured in Volts peak-to-peak (p-p).

"deplition"? I would run all of the text through a spell checker, like the one in MSWord. I didn't check for technical accuracy.

Ya good for brushing up and for desiners...