Impedance matching for active filter

[bicave]

The input stage of Active inductor BPF normally is CS, input go to gate of MOSFET ( huge impedance) we need design impedance matching.
Most of paper don't design impedance matching for active inductor BPF, however they also show S21,S11, NF?
why?

 

[edwinc]

In order to get S11 a circuit must have impedance matching, however, matching network could be off chip and it is supposed to be in the physical implementation but no necessarily on chip.