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 / S2 I8 v) ?" z3 `+ @4 g4 }
function (NTF) for a lowpass (LP) discrete-time sigma delta 0 g$ H: J9 D, [3 F
modulator, and mapped it to a CT modulator. 0 y8 d, E8 v0 G) h7 O+ X2) Secondly, replicate exactly the prototype LP / W' v+ \9 O3 \7 j7 h: m) rmodulator in order to realize the signal path for the , G U2 z* M& s" E, kimaginary signal components. , l" v ?2 i. q9 ^; T
3) Finally, add cross-coupled coefficient to perform & S; O- y, s5 R/ o" r; I1 ~/ { g
frequency-shifting from DC to the desired $ p0 @- y# T4 m7 |intermediate frequency. 8 _3 { `% n( c8 V$ c9 s4 Obut it doesn't work,my question is how to determine the feedford coefficients? 2 R* Q2 _/ {! Z+ S" M; v+ G
the method is cited from "Continuous-Time Complex Bandpass sigma delta Modulator: Key Component for Highly Digitized Receiver