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Reconstruction FILTER required for DAC8811 and OPA277 DAC Design

Other Parts Discussed in Thread: DAC8811, OPA277

Hi,

I am designing DAC interface in my board. Board is having DAC8811  and OPA277. I want to connect the output of amplifier to Re-construction filter.  Then, the load should be matched with 50 Ohm Impedance. Please select the right part for the design and send it to me.

The specifications are;

  1. Output voltage : +/-5V
  2. Type of signal : Arbitrary, Sine
  3. Operating mode : Burst, Frequency sweep
  4. Frequency range of o/p signal : 2kHz-30kHz
  5. Output impedance : 50Ω

Magalingam

  • Then, Reconstruction filter output should be Single Ended Bipolar output +/-5V.
  • Hello Mahalingam,

    Consider using one of TI's active filter design tools, either the Webench Filter Designer, or FilterPro. They are both accessable from this link:

    http://www.ti.com/lsds/ti/analog/webench/webench-filters.page

    FilterPro is mentioned on the lower right corner of the screen. Even though it is labeled NRND, it is a good, easy to use active filter synthesis program.

    If you are looking to pass a wide bandwidth of 2 kHz to 30 kHz, that is likely too wide for a conventional band-pass filter topology. The two frequencies are separated enought that this requirment might best be satified by cascading a 2 kHz high-pass, with a 30 kHz low-pass. You may find that only a low-pass is required unless something unwanted is folding back into the frequency range below 2 kHz that you want to keep out.

    The closed-loop output impedance of the operational amplifier should be low within its normal operating frequency range. Therefore, to achive a 50 Ohm output impedance you may find that adding a series 50 Ohm resistor provides a simple solution. Note however, if the resistor is added the signal at the input of stage that follows will be down -6 dB should that stage have a 50 Ohm input impedance.

    Regards, Thomas

    PA - Linear Applications Engineering