I am putting together a design for a DAC project, nothing revolutionary, but I was hoping to get some general opinions on the design of the LPF.
The DAC I am planning on using has differential current output, so the first stage will be I-V conversion for each output. After this comes my problem: I would like to have differential outputs, so I am tempted to do a 2-pole Butterworth filter (i.e. Crystal AN55, 50Hkz corner frequency) seperately on the positive and negative outputs, and use these as the differential outputs. I would then use a differential-to-single-ended converter at the amp side, reaping the benefits of balanced lines without any distortion overhead from the converter.
However, I am concerned that due to my inability to closely match resistor and capacitor values in the filter I will introduce differences between the positive and negative outputs that will reduce CMR or even degrade the actual signal.
How would you implement this? Thanks very much for any insights.
The DAC I am planning on using has differential current output, so the first stage will be I-V conversion for each output. After this comes my problem: I would like to have differential outputs, so I am tempted to do a 2-pole Butterworth filter (i.e. Crystal AN55, 50Hkz corner frequency) seperately on the positive and negative outputs, and use these as the differential outputs. I would then use a differential-to-single-ended converter at the amp side, reaping the benefits of balanced lines without any distortion overhead from the converter.
However, I am concerned that due to my inability to closely match resistor and capacitor values in the filter I will introduce differences between the positive and negative outputs that will reduce CMR or even degrade the actual signal.
How would you implement this? Thanks very much for any insights.