Well, I have never used it but there is something called a delay
locked loop (DLL) which is used, I think, to compensate for skew in
DRAM:

http://en.wikipedia.org/wiki/Delay-locked_loop

You might have a look at that, too. Good luck!

Sean


On Thu, Oct 21, 2010 at 9:05 PM, Oli Glaser <oli.glaser@talktalk.net> wrote=
:
>
>
> -----Original Message-----
> From: Sean Breheny
> Sent: Friday, October 22, 2010 1:34 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Clock IC for phase shifting
>
>>I would have thought that the standard way to do this would be to use
>>either a 4x clock and create four phases from it, or a 2x clock and
>>use both rising and falling edges to create four phases. This seems
>>like a much more solid approach than relying on a delay module with a
>>sub-cycle delay.
>
> Thanks for the reply Sean.
> Yes, I considered this first and may do it, but I should have been cleare=
r
> in my first post - the reason I want to control the phase is so I can
> calibrate the clocks as part of the ADC interleaving to compensate for
> trace/gate/parasitic delays etc. The higher the speeds the more important
> this will be I expect.
> I'm sure I would probably get pretty close with the above method if I'm
> careful, but I was hoping there was some dedicated IC that could give me =
the
> option of adjusting the clocks if needed. From what I have read in variou=
s
> HP, Agilent app notes this is the kind of thing they do when interleaving
> ADCs as one part of the calibration (others being using DACs to adjust fo=
r
> INL and DNL and so on) =A0- apparently even a couple of picoseconds at hi=
gh
> speeds can skew things quite a lot.
> I may just use complementary clocks with a programmable delay line - part=
 of
> this is also just out interest I would like to be able to put the clock o=
ut
> purposely and compile some (of my own) data on how it affects things. I m=
ay
> remove various test features later on, but it would be good to have as mu=
ch
> control as possible for this prototype version so I can work out how far =
I
> can push things.
>
>
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