Why moving one of the nondominant pole towards orgin does not improve the PM

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Why moving one of the nondominant pole towards orgin does not improve the phase margin?? Its the question in razavi's book(design of analog CMOS integrated circuit), I cant figure it out, can anybody explain it in detail? Its in the book P358.

Thanks in advance
 

The phase shifts of all poles are always added. So if you shift a nondominant pole towards the origin, this means the essential part of the phase shift of this pole becomes noticeable at a corresponding lower frequency, decreasing the phase margin of the gain curve.
 
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