sigma-delta调制器中奇次项谐波的消除

feynmancgz

回复 1# violet516


    First of all, you should know which part cause the odd-order distortion, OTA or DAC ?
    The output DR of OTA is enough ? The input amp of your OTA is small ? GBW is large enough ?
    If you use CIFF topology, the design of your summing block is good ?
    The ELD compensation's timing is correct ?
    4-bit will have a very high requirement on your DAC. The timing, overshoot, DWA.........

feynmancgz

回复 1# violet516


    In addition, is your system level design is correct ? I found that some guys use z-domain model to simulation CT-DSM, that will cause a prolem. And your solver in simulink should be ode15s or 23s, not ode45, ode45 is for DT-DSM.

feynmancgz

回复 4# mcgrady


    ode45 is non-stiff solver. CT-DSM is stiff, ode23s and ode15s are stiff solvers. they are better.
    You can use ode45, but you should use it carefully.

feynmancgz

回复 7# vdslafe


    I forget the answer to the first question. I saw it in a PhD thesis, it says it's stiff.
   
    Use ode45 is not efficient and may cause inaccurate instability.
    In spectre, if you use "conservative", it's gear2only
    ode15s use grear method, it use more equations in one step, but less steps than ode45, so it's more efficient