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ADS42LB69 Analog Inputs

Masaharu Katayama
Expert 1420 points
Other Parts Discussed in Thread: ADS42LB69

Hi 

In ADS42LB69 DataSheet, there two data about Analog Inputs frequency.

One is in the Recommended Operating Conditions on page 3. It says Maximum analog input frequency 250MHz with 2.5Vpp and 400MHz with 2Vpp.

Another is on page 6 as Analog input bandwidth. It says 900MHz at -1 dBFS differential analog input.

What do they mean?

Best regards,

Masa 

  • 0
    TI__Genius 9695 points
    Hi Masa,

    -Because of the settling time of the sample and hold at the input of ADS42LB69, the input bandwidth is dependent on the amplitude of the input signal.
    -When the signal amplitude is high, it takes longer for the S/H circuitry to settle and this limits the maximum input frequency.
    -When the amplitude of the input signal is very small, the settling time of the S/H is also very small and the input bandwidth in this case is limited by the pole of the equivalent R and C at the input which is 900MHz.

    Thanks,
    Eben.
  • 0 in reply to Ebenezer Dwobeng
    Expert 1420 points
    HI Eben,Thank you for your answer.
    May I ask what Vpp does "-1 -dBFS differential analog" mean?Best regards,Masa