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DAC7568: How to integrate an active LPF to improve the output aliasing?

Poh Kok Keng
Genius 5392 points
Part Number: DAC7568

Dear Sir/madam,

We have a DAC system and wish to integrate an active lowpass filter to improve the output aliasing, the device datasheet shows:

Using ±6V and external 5V ref, we modified to ext 2.5V ref and ±3.3V power supply, is this ok? Any proposal for the filter components? 

below are the one i draft out, any comment? 

Best regards,

kpk

  • 0
    TI__Mastermind 19086 points

    Hi,

    What's the output voltage you are looking for ? is it +/-2.5V ?

    Also cut off frequency of the filter ? Do you have any settling time requirements at the output?

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Genius 5392 points

    hi AK,

    1. Yes, required output Voltage is +-2.5V
    2. Around fs=40kHz to 200 kHz. Which frequency make sense? We want to use one channel at maximum speed or all channels at minimum speed
    3. Speed should be 1/fs , no other constraints

    Best Rgds,

    kpk

  • 0 in reply to Poh Kok Keng
    TI__Mastermind 19086 points

    Hi,

    Please find the component value for the filter.

    R1 ---> 649 Ohms

    R2 ---> 11.8K

    C1 ---> 360pF

    C2 ---> 3.6nF

    All these are designed with -3dB frequency at 50KHz.

    Regards,

    AK