Junus2012
Advanced Member level 5
Dear friends,
I designed two stage Op-Amp, I compensated my design using Poly capacitor, I needed a value of 4 PF for getting my phase margin, then I replaced the poly capacitor with mosfet transistor connected as a capacitor, now I am getting the same phase margin and or GBW as it was with poly, However I saved like 80 % area,
My question is that when MOS transistor is providing me with same capacitance value with less area, why I don't see by literature people doing it this way, is there some sideeffect which I dont know with this method ?
Note: my second stage is push pull amplifier so i need two capacitors one at the top with the PMOS and other down with the NMOS output transistor.
Thank you in advance
Best Regards
I designed two stage Op-Amp, I compensated my design using Poly capacitor, I needed a value of 4 PF for getting my phase margin, then I replaced the poly capacitor with mosfet transistor connected as a capacitor, now I am getting the same phase margin and or GBW as it was with poly, However I saved like 80 % area,
My question is that when MOS transistor is providing me with same capacitance value with less area, why I don't see by literature people doing it this way, is there some sideeffect which I dont know with this method ?
Note: my second stage is push pull amplifier so i need two capacitors one at the top with the PMOS and other down with the NMOS output transistor.
Thank you in advance
Best Regards