Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

loop filter components in passive lead lag vs active filter

BelgianWaffle

Newbie level 4
Newbie level 4
Joined
Oct 23, 2024
Messages
7
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
56
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
 

Attachments

  • passive_loop.JPG
    passive_loop.JPG
    21.7 KB · Views: 15
  • SAA1057_loop.JPG
    SAA1057_loop.JPG
    39.1 KB · Views: 16
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 "

1731552076590.png
 

Attachments

  • 1731551849517.png
    1731551849517.png
    84.1 KB · Views: 6
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)?
 

Attachments

  • SAA1057_loop.JPG
    SAA1057_loop.JPG
    90.4 KB · Views: 7
Last edited:
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. ;)
1731580189934.png

--- Updated ---

Simply choose damping factor

1731580461437.png
 
Last edited:
Ref Material, attached.
 

Attachments

  • Phaselock Techniques (Gardner-2005).pdf
    9.1 MB · Views: 4
  • PhaseLockedLoop-AN-535Phase-LockedLoopDesignFundamentalsOCR.pdf
    4.4 MB · Views: 4

LaTeX Commands Quick-Menu:

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top