Need Help To Express The Voltage! Tonight!

[Frida]

This is from a FET-transistor.

I would like to express Uut(t) with Ugs!

I would write it as: Uut(t)= gmUgs*(RL//Rs) but then the voltage amplification is not reasonable.

Thanks for the help!
/Frida

 

[Harald Kapp]

Hi Frida,
since we don't know what is to the left of the circuit we cannot evaluate Uut in terms of Ugs.
If, for example, there is an open circuit, as shown in your diagram, then you'll have a current gm*Ugs flowing through the parallel circuit of RL and RS. which would give you Uut as I*R - as you have stated.
If, on the other hand, there were a short circuit to the left of the circuit, then Uut and Ugs would have the same magnitude but reverse polarity.

Regards,
Harald

 

[Frida]

I understand, thanks for that Harald.