I'm trying to track down noise on the input side of a PCM3168a I'm using. The noise I hear is swirly in that there's a pitch that moves around in frequency.
I'm using the ADC in single-ended mode with the reference buffer shown in Figure 61 of the datasheet using these values: R1=10k, R2=1k, R3=47, C1=470p, C2=22n.
It's about a 5" run from the analog circuitry to the converter and I've placed the buffer along with the C2 caps at the analog side. Any ideas on what I can try to get this noise out?
Thanks