Distinguished Veterans,

I have at hand two fully differential switched-cap implementations of a 5th order Chebyshev and a 3rd order Butterworth low pass filter (derived from ladder RLC prototypes).  I am simulating the responses using a PAC analysis.  The phases for the clocks are such that at phi1, all nodes are discharged, and at phi2, the circuit evaluates.  The 3rd order butterworth shows the correct magnitude and phase response from PAC.  The 5th order Chebyshev, however, shows a premature droop in the corner frequency and its phase response drops down close to -420 degrees but rises a little and then falls back down.  I would expect it to fall monotonically down to -5*90 = -450 degrees.  

Switching the clock phases for the 5th order chebyshev produces the correct magnitude and phase response.  So, I am perplexed at this odd behavior, and my efforts to find literature on correct phasing of switched-cap filters is futile.  Any pointers and/or enlightenment would be tremendously appreciated.  Thank you all.