Toward high stability in active filters

Abstract

About four years ago, the consensus among network theorists was that active synthesis was headed nowhere because of high sensitivities. At that time, active filters had a well-deserved reputation among design engineers for poor stability. Practical active filters were plagued with self-oscillations, nonadjustability, nonreproducibility, and high thermal coefficients. Active network theory could accomplish nothing except explain the poor results. Since then, however, the picture has changed from total gloom to overjoyed optimism. The sensitivity problem now has several solutions, and active filters are more stable than passive filters, at least in some cases.