type 3 compensation for VMC (LTSPICE)

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chimera

Joined Oct 21, 2010
122
Hey guys. I have attached an .sch file in which Im modeling the small signal analysis of a type III compensator. I have also attached the output which Im measuring.

The op amp Ive modeled is TLC2272 and I have a compensation loop around it.

Who ever is looking at this file, make sure that when you simulate it, add the following trace in the simulation window: V(vcont)-V(n002). This will give you the actual phase and gain margin plot which a type 3 should provide.

Im having a little difficulty in understanding as to why my phase does not start from -90deg. Rather, its starts from +90 and although thats fine as the max phase delay the compensation can add is -180 (which would yield 360 phase shift total when combined with the phase shift added by the negative feedback)

Thanks!
 

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