I just need some clarification in regards to understanding MOSFET Rin and R out values
The first picture is of a BJT in small signal analysis. although it is BJT i just wish to say that i understand how the Rin values and Rout values are found in this case.
1) Now in the following image is a MOSPET problem i have been trying to solve. Ignoring the values i am just trying to get a conceptual grasp of What Rin would be and what R out would be (Ignore the fact R in is given as 500K Ohms). I have attached the small signal circuit i drew of this MOSFET circuit also. I drew the T model and Pie model.
So if we just look as the T model. To me i see that R in = (R1)||((R2||1/gm)+2Kohm Resistor) || (R4)(through the current source) ?
Would my Rin conceptual analysis be be correct here? This is were i am confused. What is the resistance of the dependant current source and R4. they are most definitely in parallel with the other circuit elements in the t model.
To analysis this would you have to look into the circuit between Rin to ground in a thevenin analysis style. And apply as current source at the input if vgs Was not given in order to solve for R4?
2) Looking at the Terminal Vo (2nd Image) and then analysisng Rout from location of Vo relevant to the t model. Would Rout=(2Kohm resistor)||((R2||1/gm)+(gm.vgs+R4||R1))?
3) How can the Pi model ignore the gm (conductance) of the mosfet. 1/gm = resistance.
Thanks guys and gals.