Hi Brian,

You should try getting some say 100pf 0603 cap's as close to
the load as possible, maybe change the 100nf for smaller
values also. The main pulse you are triggering on has a period
of about 4nsec's (250Mhz).

Darren Moore

> -----Original Message-----
> From: Brian Guralnick [mailto:[EMAIL PROTECTED]] 
> 
> DAMN ISP HEADACHES!!!
> 
> Re-send...
> > This is one of the decoupling caps between VCCINT 1.8v & GND.
> > 
> > As you can see, the 1.8v dips down to 1.625.  This creates 
> havoc with the processing inside the Altera EP20K200E which has clocks
> > running at 133MHz, 125MHz, 95MHz, & 24MHz.
> > 
> > 16KB
> > 
> ftp://ftp.point-lab.com/quartus/Public/ProtelUsers/NoiseVcc18-2ns.png
> > 14KB
> > 
> ftp://ftp.point-lab.com/quartus/Public/ProtelUsers/NoiseVcc18-4ns.png
> > 
> > Here is my current decoupling caps for the 1.8v.
> > 
> > 4 x 0.1uf smd 0805 ceramic.
> > 3 x 470uf electrolytic.
> > 
> > See the problem?
> > 
> > I originally had 32 x 0.1uf, but some rush work with cut & 
> paste at one time about 2 month ago left me with this to work with.
> > 
> > I need a temp fix where I only have 4 sets of access points 
> around the APEX part with nice Vias to 1.8v.
> > 
> > I can't get my hand on the Wima caps, any other solutions, 
> or, recommendations?


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