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THS3217: Purpose of output RLC circuit if OPS section is not used

Pradeep Prabhu G
Intellectual 560 points
Part Number: THS3217
Other Parts Discussed in Thread: AFE7225, THS4221, THS3215, THS3491

Hi Team,

We are designing a 2 channel DAC circuit using analogue front end AFE7225 part. The output of the DAC we are converting D2S by using THS3217 part and the output of THS3217 is converting 10Vpp using THS4221 part.

The query is in THS3217 part is recommended to use a external RLC filter circuit between input and OPS stage of THS3217 part.

In our DAC circuit design, we are not using THS3217 part OPS section and the output of the first stage is directly feeding to THS4221 amplifier. So in our design we are not used external RLC filer circuit recommended in THS3217 datasheet.

Please confirm whether this is required if we are not using OPS section in THS3217 part. also if required then please share the RTC filter value calculation related document

  • 0
    Guru 47545 points

    Hello Pradeep

    You tried to attached a figure but it did not come through - use the paperclip symbol in the ribbon to insert an image file, 

    Anyway, yes that is one very valid app intended for the THS3217 (and lower power THS3215). The D2S output RLC is not required, just an option - usually we would put it in there to the next stage (you say THS4221 in this cases) to provide some noise power bandwidth control. but that is optional. 

    The THS3217 was developed to upgrade AWG with the THS3491 as the new output amplifier - if the THS4221 is good enough, fine. It is almost 20years older than the new THS3491. Make sure you check you slew rate margins for your intended max output swing and frequency.