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Voltage source and current source on source electrode of MOSFET?
- Thread starter Adnan
- Start date
It is 10V, picture got disorted. Yes M1 is upside down. Source terminal is connected to the current source.
I say it is. Source needs to be connected to V4 as M1 is an N-MOSFET.
At the position of V2 seemingly 2 voltage sources are on top of another. You should clean up your schematic.
With M1 in the correct orientation, the source potential is given by V4. As Vgate= 0 V, Vgs is defined, also.
With Vgs defined by V4 and Ids defined by the current source I1 you can find the operating point (Vgs, Ids, Vds) from the datasheet of M1. The difference between Vds and V2 is the voltage drop across I1.
So how much voltage is supplied by the current source? The generic answer is: Whatever voltage is necessary to make 2 mA flow through the current source.
And vice versa: the voltage source will supply as much current as is required, 2 mA in this scenario.
Any time you have a current source in series with a voltage source, you can ignore the voltage source because the current source will output any voltage necessary to make its current happen. Putting voltage sources in series will just cause the current source to increase or decrease its voltage. How can you expect the transistor in that circuit to control the output of the current source? No matter if the transistor is connected correctly or not, if the transistor turns off, the current source will output enough voltage to arc over the transistor in order to keep its designated current existing.
If I have voltage source and current source in series, on source electrode of MOSFET how possibly can I calculate the potential on the source electrode? What confuses me is that I have current source and voltage source in series. I don't know how to approach to this problem.
Ratch
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