52.6.4.5 Interpolation Mode

The DACC integrates interpolation filters that allow OSR of 2×, 4×, 8×, 16× or 32×. This mode can be used only if Trigger mode is enabled and value in the field OSRx is not ‘0’. The OSR of the interpolator is configured in the OSRx field in the DACC Trigger Register (DACC_TRIGR).

The data is sampled once every OSR trigger event and then recomputed at the trigger sample rate using a third-order SINC filter. This reduces the number of accesses to the DACC and increases the signal-to-noise ratio (SNR) of the converted output signal.

The figures below show the spectral mask of the SINC filter depending on the selected OSR. f_s is the sampling frequency of the input signal which corresponds to the trigger frequency divided by OSR.

Figure 52-5. Interpolator Spectral Mask for OSR = 2

Figure 52-6. Interpolator Spectral Mask for OSR = 4

Figure 52-7. Interpolator Spectral Mask for OSR = 8

Figure 52-8. Interpolator Spectral Mask for OSR = 16

Figure 52-9. Interpolator Spectral Mask for OSR = 32