questions on complex bandpass CTSDM?

soupdawn

1) First, start with the design of the noise transfer
function (NTF) for a lowpass (LP) discrete-time sigma delta
modulator, and mapped it to a CT modulator.
" a: U3 C3 {6 S* e6 H2) Secondly, replicate exactly the prototype LP
modulator in order to realize the signal path for the
6 C. S4 g4 x2 N: Y# N  \imaginary signal components.
/ ?/ b9 |& g( z6 G+ J' K4 Z8 }4 U1 {8 C3) Finally, add cross-coupled coefficient to perform
* m" A. c3 w% z' l5 u- R/ zfrequency-shifting from DC to the desired
! _& {  V6 x  k. w' L5 iintermediate frequency.
but it doesn't work,my question is how to determine the feedford coefficients?
4 W, \( q0 n1 B7 T  |6 Athe method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver