A novel "Follow the master" filter
K.R. Rao, Viswanatha Sethuraman, P.K. Neelakantan · Proceedings of the IEEE · 1977
Active-R filters have their pole-frequencies directly dependent on the gain-bandwidth (GB) product of the operational amplifiers used. A novel technique, by which the pole-frequencies of the system are made to depend on a stable reference-frequency times the ratio of the GB products, rather than their absolute values, is given.