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AFE7950: DAC functionality Clarification

Marvin Gasis Arcangel
Expert 8990 points
Part Number: AFE7950

Hi Team,

The datasheet of AFE7950 mentions that "the DAC output includes a variable gain amplifier (TX DSA) with 40-dB range and 1-dB analog and 0.125-dB digital steps.". The part of the description of DSA is also "Attenuator". Can the DSA be used to actually amplify the output signal from DAC?

In the Rx chain, is there a digital band pass filter? Is it required to always use an external BPF to only feed the ADC band of interest?

I hope you can clarify and thanks in advance.

Regards,

Marvin

  • 0
    TI__Guru* 91947 points

    Marvin,

    We are looking into this.

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Expert 8990 points

    Hi Jim,

    Thank you. I am looking forward to your response.

    Regards,

    Marvin

  • 0 in reply to Marvin Gasis Arcangel
    TI__Genius 10505 points

    Hi Marvin,

    I apologize for the delay. 

    Marvin Gasis Arcangel said:
    The datasheet of AFE7950 mentions that "the DAC output includes a variable gain amplifier (TX DSA) with 40-dB range and 1-dB analog and 0.125-dB digital steps.". The part of the description of DSA is also "Attenuator". Can the DSA be used to actually amplify the output signal from DAC?

    The TX DSA can only be used to attenuate the signal from TX. Maximum full scale output power from the AFE's TX specification is for DSA = 0dB (i.e. no attenuation). As DSA value is increased, attenuation is added. 

    Marvin Gasis Arcangel said:
    In the Rx chain, is there a digital band pass filter? Is it required to always use an external BPF to only feed the ADC band of interest?

    In RX chain, there's a digital band-pass filter in decimation block to reject downsampling images and signals out of decimation filter bandwidth. However an external filter is needed to reject any out of band signals that might alias to band of interest or saturate the ADC's analog input. 

    Regards,

    Vijay