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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Best loop filter for the CS812, Wildmonkeysects? posted by Elso Kwak on March 13, 2001 at 13:02:10:
Ya hoida me?Try a 470 or 500 ohm resistor in series with 0.22 microfarads; and up the loop to 3rd order by adding a 3300 picofarad cap from the loop filt pin directly to ground. This pin is *extremely* sensitive to noise pickup, keep lead lengths short. This attempts to keep adequate loop phase margin, maintaining settling time and avoiding peaking. Unfortunately there is no single best number here, and elsewhere for that matter.
Notice the vague square law correspondence here, the resistor is about half of the data book, and the cap is about 4x. Coincidence? Synchronicity? Just math...Within [or "below"] loop bandwidth the source phase noise dominates, and above it the local vco phase noise dominates. Hence the pll "tracks" the incoming frequency and artifacts with a settling time approx inverse to the loop bandwidth, so any peaking is to be avoided.
If one has the time to twizzle, a better solution [but not the one true way (tm)] is to place the master clock right at the DACs [fed by it's own regulated power supply] registering/reclocking the DACs and "slaving" the transport to that master clock, guaranteeing synchronicity [of the clocking type, not the cosmic type] and eliminating dependence on the pll/vco.
But, I admit, it is *fun* to meet the challenge and twizzle in an attempt to extract a clean enough clock.
Share and enjoy...
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Follow Ups
- Re: Best loop filter for the CS812, Wildmonkeysects? - wildmonkeysects 15:23:39 03/13/01 (19)
- Re: Fantastic! - RonS 10:33:00 03/16/01 (1)
- Re: Funtastic! and call for creativity - wildmonkeysects 13:26:54 03/16/01 (0)
- Re: Best loop filter for the CS812, Wildmonkeysects? - RonS 15:00:45 03/14/01 (1)
- Mostly universal loop filter for 8412 - wildmomkeysects 15:15:28 03/14/01 (0)
- Re: FANTASTIC, Tweak of the Year! - Elso Kwak 03:54:02 03/14/01 (12)
- Re: FANTASTIC, Tweak of the Year! - wildmonkeysects 15:04:44 03/14/01 (10)
- Re: FANTASTIC, Tweak of the Year! - Elso Kwak 05:18:01 03/15/01 (7)
- The ol' workhorse 8412 - wildmonkeysects 13:21:47 03/15/01 (2)
- Non OS PCM63s ? - Daniel Espley 04:31:15 03/17/01 (1)
- That classic DAC PCM 63 - wildmonkeysects 14:34:57 03/19/01 (0)
- More insightfull info from Elso. - -Steve 12:39:46 03/15/01 (3)
- Re: Rosie has a big honkin phat ground plane - wildmonkeysects 13:26:11 03/15/01 (2)
- Re: Rosie has a big honkin phat ground plane, MSB adj. - Elso Kwak 17:24:38 03/15/01 (0)
- Awful, AWFUL mental picture. Rosie's "groundplane". - -Steve 14:12:45 03/15/01 (0)
- WOW! - -Steve 18:58:12 03/14/01 (0)
- Er, make that microvolts, not nanovolts... - wildmonkeysects 16:09:56 03/14/01 (0)
- Yes, indeed. - -Steve 11:28:21 03/14/01 (0)
- Thanks. I'm gonna try it too. <nt> - -Steve 15:52:31 03/13/01 (0)
- Re: Best loop filter for the CS812, Wildmonkeysects? - Elso Kwak 15:34:48 03/13/01 (0)
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