AC coupling using NMOS and PMOS

[nobrainer612]

AC coupling using NMOS

Hello. What does AC coupling by using NMOS and PMOS actually means?

 

[yungman]

The drain of M2 is AC coupled by C2 to drive the load R4.

The way the circuit work is M1 have the gate and drain shorted to set up the current which mirror to M2. The drain of M2 has positive voltage. So AC coupling is needed to bring it to ground reference level.

 

[nobrainer612]

Homework Statement

The problem is to perform AC coupling by using NMOS and PMOS

Homework Equations

The Attempt at a Solution

AC coupling by using NMOS is solved. Then I tried to build one by using PMOS, but the result from these 2 are different.

This is the NMOS circuit:

This is the result waveform from this circuit:

This is the PMOS circuit:

This is the result waveform from this circuit:

 

[NascentOxygen]

Perhaps you'd better explain what you don't like about the second circuit. It seems to me that in both you achieved an output of 200mV p-p, so I don't see anything amiss.

(I won't be able to help you further, but if you explain this, someone may be able to.)

 

[nobrainer612]

my question is, shouldn't the blue wave from the circuit built by PMOS has the same waveform and value as NMOS?

 

[NascentOxygen]

my question is, shouldn't the blue wave from the circuit built by PMOS has the same waveform and value as NMOS?

Oh! The invisible blue waveform. I had not noticed it!

I now understand your concern.