about FSK data question....

super

Dear all :
0 Z1 N  Z! Q4 [+ r: D) D  T              In fsk close loop direct Frequency modulation ,
          1.  data rate is higher than loop BW  or lower than loop BW ?
, ~% i* m6 x8 @- {" m          2.  And what's the relation between data rate and Loop BW ?

7 X5 t7 R$ i$ R, O% z           Because modulation from VCO , it's a high pass function for VCO vs PLL.
' F: q, g' e* s' a. Z& n           If modulation frequency > BW , it will be supress by VCO vs PLL transfer function.
           It will be trace and fix it.  So modulation function is fail.
9 }2 s* t3 Y* t! k' @. C* ~; {             Is this concept is right ?
                  
% ^4 F  O# u7 E& E1 f- {: @                    Thanks .

simenkid

1.data rate可以高於loop bandwidth, 也不可以.端看用什麼architecture
+ B  Y% h# r4 L3 U8 V$ |: J+ C! y2.假使單純在multi-modulus或是由reference端做調制, data-rate高於loop bandwidth則勢必產生失真

直接由PLL Synthesizer調制提升FSK, FM, GMSK等固定波包調制之data rate
$ O+ D2 k6 [0 b" c可選擇如pre-emphasis或two-point modulation(同時兼顧inband與outband,理論上無頻寬限制)的方式