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
: V$ M1 m8 t1 m8 ]: `modulator, and mapped it to a CT modulator.
2) Secondly, replicate exactly the prototype LP
; R2 j; b3 A2 \6 g3 f% f8 V4 Smodulator in order to realize the signal path for the
imaginary signal components.
8 h& Y, y$ Y7 [& \1 g- g3) Finally, add cross-coupled coefficient to perform
( O& b) g" }) c2 G/ m' K# }  xfrequency-shifting from DC to the desired
intermediate frequency.
. |, t! q6 x; A1 Z2 }" dbut it doesn't work,my question is how to determine the feedford coefficients?
the method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver