loop filter components in passive lead lag vs active filter

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BelgianWaffle

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Hello all,

I've always been unsure which compoents (2nd and 3rd order) correlate between a passive lead lag and an active filter.
Take for example ChangPuak's online loopfilter calculator (attached). (https://www.changpuak.ch/electronics/pll_loopfilter_calc.php) :

Wrt components R2 - C2 and R3 - C3 in the loop filter calculator

Is it a fair assertion to say that eg. in the loopfilter for an SAA1057 :
that
R2 corresponds to the SAA1057 18 k resistor,
C2 corresponds to 330 nF cap
R3 corresponds to the SAA1057 10 k resistor,
C3 corresponds to 330 nF cap

?

I'm ignoring C1 in the loop calculator for now....

TIA! 73
 

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No.
You are looking at Out to In feedback gain amp. p6 to 5.

The PD is sampled by pins 1,2,3 to create dual slope filters, resistor/capacitors for sample and hold circuit
do not match your circuit.

"The output voltage at TCB and TCA is typically 1⁄2 VCC2+0,3 when the tuning system is in-lock via the sample and
hold phase detector. The control voltage at TCB is defined as the difference between the actual voltage at TCB and
the value calculated from the formula 1⁄2 Vcc2+0,3 "

 

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Thanks for reviewing!
I cannot make sense of the loop filter calculations in AN196/AN197 (https://bitsavers.trailing-edge.com...inear_Data_Manual_Volume_1_Communications.pdf)

Can you provide a simpler way to calculate the amp feedback & loopfilter provided for the SAA1057? I've been stuck on this for weeks now.

Also, I'm not referring to the S&H circuit... I'm referring to the loopfilter and the pole on the output amp (circled)?
 

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Last edited:

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I didn't find a formula yet just 18k 330 nF, tau=6ms but T=1ms for FM and depends on VCO
--- Updated ---

Found it

I might put it into a spreadsheet , compute and plot the results for Bode Plot. I suppose a slide Rule is out of the question.

--- Updated ---

Simply choose damping factor

 
Last edited:

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Ref Material, attached.
 

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  • Phaselock Techniques (Gardner-2005).pdf
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  • PhaseLockedLoop-AN-535Phase-LockedLoopDesignFundamentalsOCR.pdf
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