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ADS6224 Excessive Radiated EMI

Other Parts Discussed in Thread: ADS6224

We’re observing a pretty significant spike at 300MHz and 500MHz in our radiated emissions scans, and have been able to isolate the source to our ADC interactions with the Altera Arria II FPGA. We are utilizing a Texas Instruments ADS6224 in our design. What is the best strategy in troubleshooting this guy for EMI performance?


Adam Garrison

  • Hi Adam,

    There are a few serial registers that can be used to narrow down if it is indeed coming from the digital interface. Take a look at registers 0x10 and 0x11 in the datasheet. You'll see options to change the current of the data bits and clocks and options to add internal termination. If you set bits [3:2] of 0x10 to 10 the current should drop and you should see a reduction in the amount of emissions.

    You can try doubling the LVDS current and then enable 100 ohm termination in the part and see if it has any effect on the EMI performance. Otherwise the layout may need to improve to reduce the emissions.

    Matt Guibord