[time-nuts] Multiple Time Interval Counters to measure Transients?

[Javier Serrano]

On Mon, Sep 10, 2012 at 9:08 PM, Florian Teply <usenet at teply.info> wrote:

> Apart from that, I'll also check with ACAM in Germany as they have
> ready-made chips that would do that, and 65 to 120 ps RMS accuracy is
> okay for the CMOS stuff. Maybe they sell their chips for only a few
> hundred euros each... ;-)

You might also want to have a look at this FMC with an ACAM chip on it:
http://www.ohwr.org/projects/fmc-tdc/wiki

It is made to work with this FMC carrier in PCIe format:
http://www.ohwr.org/projects/spec/wiki

The FMC carrier is a mature product. The TDC FMC is soon going to be
commercialized. The design is open, so it could give you some ideas in
any case.

We have also played with a TDC core in the FPGA
(http://www.ohwr.org/projects/tdc-core/wiki) using the same FMC
carrier with a simple digital I/O mezzanine
(http://www.ohwr.org/projects/fmc-dio-5chttla/wiki). This core is
based on delay lines inside the FPGA, using logic elements. In your
case it looks like a solution which would enable more channels in the
FPGA at the cost of some accuracy would probably suit better. You can
do this by e.g. sampling inputs with different phases of clocks in the
200 MHz realm, using the internal PLLs of FPGAs.

Cheers,

Javier