標題: questions on complex bandpass CTSDM? [打印本頁] 作者: soupdawn 時間: 2009-4-10 01:06 PM 標題: questions on complex bandpass CTSDM? 1) First, start with the design of the noise transfer + H' P; r( W ~& e( v- I
function (NTF) for a lowpass (LP) discrete-time sigma delta 2 [6 E3 @3 |' |5 V8 tmodulator, and mapped it to a CT modulator. 8 Q( K, l x" T& G3 t% ]2) Secondly, replicate exactly the prototype LP , D" m' U) T, V# p0 j
modulator in order to realize the signal path for the # Z3 O0 }* F9 l% F' D9 G, J
imaginary signal components. 5 x8 I; V7 t8 @
3) Finally, add cross-coupled coefficient to perform & y6 Q+ |: V& F; t& xfrequency-shifting from DC to the desired 5 B" t$ z# t" u3 e8 o9 t
intermediate frequency. 5 z1 m/ j. ~- x, ~7 d! \
but it doesn't work,my question is how to determine the feedford coefficients? 7 k% ?% p6 @2 j3 z
the method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver