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How to design an active loop filter for PLL

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dicket

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active loop filter

I have two questions:
First,when I have known loop badwidth and phase margin,how to determin the components values?how to get an expression of the loop filter transfunction?
Second,how to select the OP-amp?what role does the op-amp play?what effect on PLL performance does the parameters such as INPUT RAIL,OUTRAIL and SLEW RATE make?
Thanks.
 

active loop filter design

For a fourth order active loop filter,How to determinate the value of C3 R3 C4 R4the higher stage of the filter?
 

active filter pll

Hi,for the fourth order active loop filter shown below, how to calculate the value of C3 , R3, R4? In the book ‘PLL Performance, Simulation, and Design 3rd Edition’ written by Dean Banerjee, it gives that C3=C4*4T3*T4/(T3-T4)^2 ,R3=(T3+T4)/(2*C4) , R3=(T3+T4)/[2*(C3-C4)],but I do not know how to get these formulas. Could you give me some guide or help?
Thanks.

Added after 7 minutes:

18_1168156157.GIF
 

pll active filter

please reffer to
**broken link removed**
 

pll active loop filter

dicket said:
I have two questions:
First,when I have known loop badwidth and phase margin,how to determin the components values?how to get an expression of the loop filter transfunction?
Second,how to select the OP-amp?what role does the op-amp play?what effect on PLL performance does the parameters such as INPUT RAIL,OUTRAIL and SLEW RATE make?
Thanks.
Click to expand...

If you design this active filter for PLL, please care about the OP poles, this will influence the PLL own poles and zeros.
 

pll active loop filter design

Yes, normally the opamp poles will have an influence of 1% or even smaller.
 

active loop filters

note the nonlinear effect on the loop
 

Hi.
I think that the input bias and offset current of OPAMP is important for spures in Spectrum and the noise of opamp affect the phase noise of PLL.
 

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