Hello All,
This is an online electronics 1 class. I only talk to teacher through email and he is cryptic. I am really frustrated. I should not be getting a negative solution for resistor RD. My Professor says the value highlighted in yellow should be under 50. The only way I can see to make this happen is to change gmo from 6.4*10^-3 or 6.4mS to just 6.4 S. I looked in the book at an example spec sheet for a Fairchild 2N5457 N-channel Amp. They list gos (output conductance as a value between 10 -50 micro mhos. so in this problem is the value of Yos = 20 micro mS or 20*10^-6 mS, where I was interpreting Yos as 20*10^-3 S.
Thank you for any help, trying to do this with work, kids, wife and everything else is hard.

 

Change Yos to 20μS and repeat the calculations. RD will be around 1.9kΩ. For Yos =20mS is impossible to get any gain from this circuit Av_max = 6.4mS/20mS = 0.32 [V/V]

 

Change Yos to 20μS and repeat the calculations. RD will be around 1.9kΩ. For Yos =20mS is impossible to get any gain from this circuit Av_max = 6.4mS/20mS = 0.32 [V/V]

Thank you, I had gone down this road because the textbook gave all problems with a Yos in the microamp range. The textbook had a section on design problems that is why I solved the problem the way I did. I thought maybe that you might run into this problem when designing JFET amplifiers but now I think it was a typo in the assignment. Thank you for the help.
Cheers,
Tony