From: Jason Zheng ([email protected])
Date: Thu Nov 04 1999 - 19:17:37 PST
Thank you very much for the reply!
The 240 Mhz part is to buffer the clocks from clock synthesizer
to multiple ASICs as a clock source. The ASICs have 3.3v IO but
are 5V tolerate. I saw and IDT part# IDT74ALVC16244A that may
be promising. Have you had any experience with that part?
Do you know of any GaAs vendor that may provide faster
parts for my needs? I wonder what people use for buffering
the clocks for AMD's 200 Mhz system clock or DDR clocks?
Can you give me a pointer for the GAL part#/vendor info?
Thanks in advance!
> From your post, I guess that you want 3.3V SSTTL levels. 240MHz is really
> beyond any practical upper limit for SSTTL. There isn't much out there that
> can reliably get below a Tpd of 1.5nS, which would typically be suitable to
> 150-166MHz at the high-end. If you want to reach beyond 200MHz, it is time
> to use low-swing logic.
> The application sounds like a phase-splitter. If it is, instead of an
> inverter try a precision delay line, either buried in etch, or off the shelf.
> The 120MHz mux / FF can be implemented in either a 5nS or 3nS GAL. Which
> grade is appropriate depends on the specifics of your Tsu and Th
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