Amplifier with Current Source Load.

Thread Starter


Joined May 27, 2020
I would need your help in understand the working of this circuit [attached]. Initailly i will mention my understanding , correct me if i am wrong and finally i will ask question. My understanding: "A modulated signal is capacitively coupled using C2 =1pF , a MOSFET amplifier with current source load amplify and retrieve the orignal signal from modulated signal which is finally inverted using inverter" Now i would like to know:
1)What if i increase or decrease the coupling capacitor ? what will be its effect on siganl and on overall system? How to calculate it?
2)How MOSFET amplifier with current source load and capacitor C1 demodulate the signal? What will be the effect if we increase/decrease current source load (Id current)?
3) What is the role of C1 ? how to calculate its value ?




Joined Jul 11, 2016
the capacitive coupling to 100/60k voltage divider is a "not too good idea" = the reliable control of the driving stage is "narrow" e.g. hard to achieve
although -- such scheme might be sufficient for some specific OUTP control

the C1 collects/accumulates the "charge" from CC and is dis-charged by pull-down mosfet (it can't be more the R.ds.on can handle for the pull-down MOS-Fet not "fusing" it)