> The freq range is potentionaly from 247 hz up to 12.5 kHz so an
> active filter is needed (I think). Can any body point me in the right
> direction?

Are you generating the frequency by adjusting the PWM of the output,
or the frequency of the PWM generator with a constant 50% square wave?

If doing the first then the frequency to consider is the PWM frequency
as being the frequency to filter. If doing the second you will need a
tracking filter as your lowest frequency is less than 1/3 the highest
frequency (check harmonics of a square wave for the reason why).

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