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.
7 {$ G& P1 R: d7 l: L2) Secondly, replicate exactly the prototype LP
modulator in order to realize the signal path for the
) x( y# S& Z6 V# k* H/ f, }imaginary signal components.
3) Finally, add cross-coupled coefficient to perform
frequency-shifting from DC to the desired
, G) z2 s, ~: H: kintermediate frequency.
but 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