Gain derivation of pmos amplifier

[silversgleaming]

Do you have any idea how to derive the gain of this amplifier (including gm1,gm2,gm3,..,gm8)??

 

[Dominik Przyborowski]

I believe that output nodes are 5 and 6.

If You draw a small signall circuit You will see a symetry and whole small-signal circuit will reduce to current sources \[g_{m1} V_{in}\], \[-g_{m6} V_{in}\] and resistor \[1/g_{m3}\]. Then your gain should be equal to \[K_V=\frac{g_{m6}-g_{m1}}{g_{m3}}\]

Of course If I didn't made any mistake ;-)

 

[skamthey]

I think the gain will be : gm_x1 * ((1/gm_x3) || (rds_x7) || (rds_x1))
Which on approximating Gain = gm_x1* (1/gm_x3) = gm_x1 / gm_x3