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Altera_Forum
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19 years ago

RIPPLES IN SUPPLY OF FPGA_plz help

HI everyone..... Iam using a stratix II device. Before programming the PLL section of FPGA, supplies are observed correct i.e. 1.21V and 3.29V. As soon as I program the device, the supplie...
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Altera_Forum
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19 years ago

The ripple you are seeing could come from a number of contributors. Most often dc-dc supply is undersized (LC too small or freq too low). What frequeny is the ripple you see? Less than 1MHz your dc-dc convertor is the prime suspect.

You should also make sure you don't have any shorted i/o. I always tell Quartus to set all unused io to tristated inputs rather than the default outputs driving ground.

If the ripple/noise you see is much higher like 10's of MHz+ then you should examine your power supply filtering and decoupling.

Hope this helps,

Chris