questions on complex bandpass CTSDM?

soupdawn

1) First, start with the design of the noise transfer
  h) e8 w! i  O7 \3 ^function (NTF) for a lowpass (LP) discrete-time sigma delta
# z) |1 K+ r1 k( b3 v, I. tmodulator, and mapped it to a CT modulator.
  \0 S( X( ], F# N+ L" s: x  }. D+ K2) Secondly, replicate exactly the prototype LP
modulator in order to realize the signal path for the
0 x+ N" w' B0 limaginary signal components.
3) Finally, add cross-coupled coefficient to perform
frequency-shifting from DC to the desired
intermediate frequency.
but it doesn't work,my question is how to determine the feedford coefficients?
8 c9 ^1 Z4 k, ~the method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver