[time-nuts] High rate, high precision/accuracy time interval counter methods

[Richard (Rick) Karlquist]

HP/Agilent/Keysight laser interferometers
measure at the kind of rates you are talking
about and (last time I heard) could divide
an interference fringe down to 1/512 of a
wavelength.  As you say, they definitely use
an ASIC with a ring oscillator.  Perhaps
there is some way you could repurpose the
interferometer electronics to make your
measurement.

You also might consider that over 25 years
ago, HP developed the 5313X counters with
interpolators implemented in FPGA's.  The
FPGA's available now are vastly more
sophisticated and much faster.  Perhaps there
is a way you do your ASIC in an FPGA.

If you really do need an ASIC, the best way
to get that done is to partner with a university
and have some PhD student design it.  Universities
often have arrangements to do this.

Rick

On 5/3/2016 5:31 AM, Attila Kinali wrote:
> Hi,
>
> We had here a discussion about measuring events (ie time stamping
> them precisely) with high rates. As some of you know, Javier and
> his group, Bruce and me are working on a system that should give
> us something better than 10ps (my guess is that we should get close
> to 1ps) at a rate of (guestimated) 1MHz per channel. (Based on the
> excitation of a LC tank and measuring the ring-down/phase with an ADC).
>
> As it is with researches, we want the moon, and prossible even more.
> So we were talking about getting the measurement rate up even higher,
> to 10MHz and if possible 50MHz with the same precision. The above
> approche will not work above 1MHz. Using different filters it might
> be possible to get it up to maybe 10MHz, but it would be an awkward
> design at best.
>
> The only methods I am aware of (and could find) that achieve such high
> rates are those, based on (vernier) delay lines (and their equivalent
> ring oscillator ones) in ASICs. But this means that a costly ASIC needs
> to be produced.
>
> Does someone know of other methods that could achieve high measurements
> rates with better than 10ps precision/accuracy? (This question is mostly
> a hypothetical question out of interest, I don't plan to build one...yet :-)
>
> 			Attila Kinali
>