SPRZ519 august 2023 IWR2243
Spurs Caused due to Digital Activity Coupling to XTAL
IWR2243 ES1.0, ES1.1
Digital filtering activity can potentially couple to XTAL pins and lead to spurs in the RX ADC output. The spur frequencies depend on the sampling rate (Fs) and DFE modes. The strongest of these spurs have been observed when Fs is close to 10-, 12.5-, 20-, 25-Msps within ±1.5 MHz. In these ranges, an IF spur can appear at about 2Fs-40 MHz, 4Fs-40 MHz, 4Fs-100 MHz, and 8Fs-100 MHz.
Workaround #1:
Avoid sampling rates close to these numbers (10-, 12.5-, 20-, 25-Msps) or use exactly these numbers (spur is at 0 Hz in the latter case).
Workaround #2:
Using external TCXO, instead of XTAL, can avoid these spurs.