questions on complex bandpass CTSDM?

soupdawn

1) First, start with the design of the noise transfer
4 @$ X; q/ o, ]3 d+ N( [8 y: g# Efunction (NTF) for a lowpass (LP) discrete-time sigma delta
modulator, and mapped it to a CT modulator.
3 u# M6 h# p% P1 h" |5 s( Q2) Secondly, replicate exactly the prototype LP
+ c" e- `$ B" W- `' `; G3 u6 ~) ^& mmodulator in order to realize the signal path for the
/ z9 e7 t$ v) h' z# V# @9 G2 W3 O% Ximaginary signal components.
3) Finally, add cross-coupled coefficient to perform
5 A% j' H. a( N+ Efrequency-shifting from DC to the desired
intermediate frequency.
) \4 b* C* J5 i! J' i  Obut it doesn't work,my question is how to determine the feedford coefficients?
: K2 A  u3 _$ v6 A5 Wthe method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver