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PLL Pspice model or interface Pspice & Matlab

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Sergiu_Q

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pll spice model

Where I can find a spice model for PLL ?...any suggestions ? In princilpe I need a model for lmx2316 but I think I can modify a model for can be aprox the model I need .Is a good ideea to interface my circuit from orcad pspice , with Matlab Simulink? (my circuit from orcad , PLL from matlab and all simulations I need will be in Simulink )
 

biff44

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pll pspice

What are you trying to model?

It is a control loop. You can use something like Pspice to model it open loop characteristics by using voltage equivalent representations. Oscillator is an integrator with gain Kosc (like [MHz/V]/s), phase detector is a contant Kp [volts/radian], digital divider is a constant K=1/n, loop filter is an op amp wired as an integrator, etc.

I am not sure if you can close the loop in Pspice and get it to converge on a solution, but it is worth a try.
 

Sergiu_Q

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pspice pll model

biff44 you have right but I can't make a too precise model in the mode you explain...how about the interface pspice& simulink ..it is posible in this case?
 

khouly

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pspice pll

simply try to biuld ur model using analog behavioral modeling library
i have a frirnd done it


khouly
 

biff44

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pll + linear model + spice

No, let me try again. Are you simply trying to analyze steady state conditions, such as loop bandwidth, noise, etc; or are you trying to model non-linear effects like cycle slipping, acquisition time, etc?
 

Sergiu_Q

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pll pspice simulation

will be good if I will can do all , but for first I need to have a model for max2316 for I can simulate a circuit who use that circuit ...I have the rest of the circuit ready but I need only this pll model ...I need only usual things about this (dc, noise , bandwich) aquisition time is already to much for what I need :)
 

biff44

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spice control loop model pll

Start with using this website. It has a lot of the linear basic theory programmed. Pick a national pll chip that is similar (ie same charge pump output current) as the MAX part, and away you go.

If you stay in the linear region, PLL's are very simple linear control loops. Any good program with a control loop analysis package can be used. That would be a second step, if you had more complicated PLL's with lots of extra poles and zeros, or phase and frequency parallel control paths, etc. (to do so, you would have to already be familiar with concepts like Bode diagram, Root Locus plot, Nyquist criteria, etc).


https://www.national.com/appinfo/wireless/webench/
 

amraldo

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spice model matlab

For interfacinf the spice output with matlab.
You will first generate a net list.
Then at the end of the generated file insert the command tran (check the syntax in spice manuals).
This command will generate a .txt file that can be opened & processed using matlab.
 

Sergiu_Q

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pll spice simulation

Biff44 thanks .I already used webench and theresults are ok for my circuit , but now I need to test my complete schematic :)
I will try to make my schematic like a subckt and to use this subckt in matlab and in matlab I will use the pll from simulink (I will make my own model using the pll from simulink , with my pll characteristics )
amraldo "Then at the end of the generated file insert the command tran (check the syntax in spice manuals).
This command will generate a .txt file that can be opened & processed using matlab."
..what command man ? .tran is only for I can do a transient analysis .
please be mo explicit ...maybe you know more and I make a confusion
 

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