The MAX291 series is designed to deliver performance with minimal external components.
However, if you are experiencing issues with harmonics of the switching frequency, it may be beneficial to consider the filter's design.
The MAX291/MAX295 Butterworth filters provide a maximally flat passband response, while the MAX292/MAX296 Bessel filters offer low overshoot and a fast settling time.
The design task primarily involves selecting the appropriate clock frequency that controls the filter’s corner frequency. If you continue to see harmonics, it might be worth exploring the capacitor size and switching frequency adjustments, as these can significantly influence the frequency behaviour of the filter.