This is a strange mixture of a VCO and a switched
capacitor filter based on the filter presented by
Jan Hall, as presented in Electronotes EN92 P14-15,
which was in turn based on an idea in a 1974 issue of
Electronic Design on a Biquart (twice the order) filter.
If you are after something different, this fits the bill. After all, how many filters have a sync input?
Soundsample: Bi-N-Tic used as VCO with MFOS 12db LP controlled by ADSR...