Relationship between switching frequency and radiated emissions in Capsense

[YoIs_1298666]

Hello,

We can see reports of radiated emissions in CapSense on AN64846 and AN85951.

Generally, the emission should be large at odd-numbered harmonics of the switching frequency, but from this figure, it seems that it is maximum at 24 MHz, which is an even-numbered harmonic. Why?

Best regards,

Yocchi

[LinglingG_46 · Accepted solution]

There are other signals on the board, but keep others the same, the figure shows the relationship between sensor clock and  the emission.