In ADC_DelSig manual page 4 there is a note related to Fast Filter conversion type:
Note Care should be taken when switching signals between ADC conversions. Either switch the input quickly with hardware control or Stop the ADC while switching the input then restart the ADC after the new signal has been connected to the ADC. Failure to do this may result in crosstalk between signals in the ADC results.
Does anyone know what Author had in mind saying "fast hardware switching"?