Hi Sylvain.

Sorry for so delayed reply, I've found that I've lost subscription for this mailing list.

Well, actually DC/DC were synchronized (between each other) even in the very first UmTRX version.

On the first versions I saw spurs from DC/DC ~500 kHz at the TxPLL noise plot (few in case of non-sync) and some other surprises.

You can see issue #42 here:

https://code.google.com/p/umtrx/issues/detail?id=42&can=1&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20Modified

Nowadays, we use DC/DC chip TPS54560, synchronized to 541 kHz signal (26/48) from FPGA.

No surprises noticed anymore, but actually, we chose TPS54560 because of better efficiency and higher input voltage.

Best regards,

Andrey Sviyazov

---------- Forwarded message ----------
From: Sylvain Munaut <246tnt@gmail.com>
Date: Sun, Nov 8, 2015 at 11:12 PM
Subject: Regulator Synchronization
To: umtrx <umtrx@lists.osmocom.org>

Hi,

I know that on the UmTRX the switching controllers ( ST L5973 ) are
all synchronized together.

IIRC the earlier versions of the UmTRX didn't have this and I'm
wondering if you really noticed a difference due to this change ?

Cheers,

Sylvain