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AWR1642: How to config the IF band-pass filter?

Part Number: AWR1642

Hi,

It's said in the Awr1642's datasheet that 'the band-pass IF chain has configurable lower cutoff frequencies above 175 kHz and can support bandwidths up to 5 MHz'. And there are two high-pass filters(hpf) whose cutoff frequencies are configurable and their available corner frequencies are different. 

My questions are as follow:
1. Are the lpf cutoff frequencies configurable? If not, will the the lpf cutoff frequency adjust automatically according to the ADC sample rate? If the ADC sample rate is 3MHz, will any high frequency signal alias back in the pass-band?
2. Why there are two high-pass filters? Are they for I and Q channel respectively? Why do they have different available frequencies?  Should they be configured to the same cutoff frequency?
3. Can we disable the high-pass filters?
Thanks a lot!
Frank

 

  • Hi Frank,

    1) I'm afraid the LPF cutoff frequencies are not configurable. By design, the high frequency signals will not alias back in the pass-band.

    2) The two high-pass filters are primarily there to achieve a higher rolloff. They have independent configurability of cutoff frequency, and the user could make use of this as needed.

    3) The high-pass filters cannot be disabled.

    Best Regards,
    Anand
  • Hi Anand,

    Thanks a lot for your reply!

    'By design, the high frequency signals will not alias back in the pass-band.' Do you mean that even if I use a low sample rate like 1MHz, the filter will filter out signals with higher frequency than 1Mhz?

    'The two high-pass filters are primarily there to achieve a higher rolloff.' So there are two hpf for each channel and they work together, right?

    Thank you again for you reply!

    BR,
    Frank
  • Hi Frank,

    Yes, even with a low sampling rate, the filter will filter out signals with higher frequencies.

    Yes, there are two HPF filters for each channel and they work together.

    Best Regards,
    Anand
  • Thank you, Anand!