I had designed a TT biquad complex Active-RC filter with 4 inputs and 4 outputs  
The inputs  are Iin+,Iin-,Qin+,Qin-; outputs are Iout-,Iout+,Qout-,Qout+
They consctruct complex singals by set the ac source with different phases.
I had measured the AC response and Image reject ratio.
But nothing I can do to measure IIP3 & SFDR
I had read the paper "Accurate and Rapid Measurement of IP2 and IP3" provided by website and some other documents like cadence spectre documents.
The documents provided detail simulation method in LNA & Mixert,But in complex filter I don't know how to deal with two signal route and four ports.