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ADC12DJ5200RF: Oversampling

ttd
Mastermind 9445 points

Part Number: ADC12DJ5200RF

Dear Technical Support Team,

Could you please confirm if my understanding is correct?

When a signal with a bandwidth of 200 MHz (9 GHz ± 100 MHz) is input to an ADC,
oversampling is possible if the sampling frequency is at least twice the bandwidth (400 MHz).

Conditions:

Input range: Usable input frequency range: > 10 GHz.

Best Regards,

ttd

  • 0
    TI__Prodigy 10 points

    ttd,

    You cannot use oversampling to capture the band of interest you described. The ADC12DJ5200RF can sample at up to 10.4 GHz in single-channel mode, so the Nyquist boundary is at 5.2 GHz. Since your signal is within 9 GHz ±100 MHz, according to Nyquist's theorem the signal will alias into the first Nyquist at 1.4 GHz ±100 MHz.

    In order to capture this signal you can apply an analog filter before the ADC input to isolate the band of interest and then use the DDC block to perform 8x decimation (at 10.4 GHz sampling frequency) or 4x decimation (5.2 GHz sampling frequency), which will bring the effective sampling frequency down to 1.3 GHz. In this case the first Nyquist boundary is at 650 MHz and the signal aliases to be within 0-200 MHz. The analog filter attenuates all other signals that can alias into the 0-200 MHz region, so you know this tone is your signal of interest.

    Can you provide more details about your application so that I can give you a more specific recommendation?

    Thanks,
    Sam