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circuit

Additional info includes Vss=0V, Vdd=3V. Also assume saturation (since we have Vd=Vg) and λn=0. We also know the reference current but not the Resistor. I know Vgs and thus Vds but I am looking to find Vs/Vd/Vg. I am guessing that there is a voltage drop across the current source so it is not as straightforward as Vd=Vdd=Vg.

Can we calculate those voltages?

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  • \$\begingroup\$ Homework? What have you accomplished so far? \$\endgroup\$ – PDuarte Jun 2 '18 at 14:59
  • \$\begingroup\$ Not homework, studying for exams. Proved strong inversion and saturation, determined Ir current and found Vgs from square law. \$\endgroup\$ – Kiotis Jun 2 '18 at 15:11
  • \$\begingroup\$ Do you know Ib? \$\endgroup\$ – The Photon Jun 2 '18 at 15:27
  • \$\begingroup\$ Yes, it is 100μA and I am also aware that it is equivalent to Ids. \$\endgroup\$ – Kiotis Jun 2 '18 at 15:30
  • \$\begingroup\$ You have Vs.... \$\endgroup\$ – PDuarte Jun 2 '18 at 15:36
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Do we have a voltage drop across this ideal current source?

Yes, an ideal current source will produce whatever voltage drop is necessary to maintain its defined output current.

Additional info includes Vss=0V, Vdd=3V.

Because of the ideal current source, the value of Vdd is irrelevant. If it were 13 V, the current source would just drop 10 V more; if it were -7 V, the current source would just drop 10 V less.

I know Vgs and thus Vds but I am looking to find Vs/Vd/Vg.

There are no Vd, Vs, or Vg defined in your schematic, so this is impossible to answer.

You will be able to find Vs1 and Vg1 as expressions involving R.

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  • \$\begingroup\$ Thank you for your answer :) My textbook has missing info on some exercises and it's impossible sometimes to be sure whether I am thinking about it properly or not. \$\endgroup\$ – Kiotis Jun 2 '18 at 15:46
  • \$\begingroup\$ Textbooks don't show step by step solutions because the author typically likes to believe that you're capable of understanding the topic with ease... Whether that's good or bad practice is debatable depending on the quality of the material in the textbook. For instance, if you're taking a class in electromagnetics, the textbook may end up skipping a lot of steps for problems involving the use of calculus. This is because the author assumes that you have taken calculus beforehand. That's probably the same for electronics. Authors assume that you know about circuit analysis already. \$\endgroup\$ – KingDuken Jun 2 '18 at 16:09

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