Electronic – Differential low pass filter to single ended -> Differential low pass filter

differentiallow pass

I'm designing an audio DAC based on the PCM1690 from TI. Datasheet

One requirement of the DAC is differential outputs. Since the PCM1690 has differential outputs, this is not a problem. However, the design of the low pass output filter is unclear for me. Figure 40 of the datasheet shows an example circuit, but this circuit converts the signal also from differential to single ended. What changes are needed to make this circuit a differential low pass filter alone? My assumption is to remove C1 and R1, R2 and R3 connected to the + input of the opamp. Is this correct?
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Best Answer

One option is to use a fully differential amplifier for your op amp. The MFB filter for that type of amplifier looks like (source):

Multiple feedback (MFB) topology FDA Filter

As you can see, it uses the same number of parts as the filter you reference, with the added advantage that you can also set the output common-mode voltage.

Full design details can be found in this application note: https://www.ti.com/lit/an/sloa054e/sloa054e.pdf