Active filters with low sensitivity to element changes

The active element has the greatest influence on the properties of active filters and may cause oscillations especially in more complicated networks. An active filter network is described which is almost independent of element changes. The analysis shows that the constant of the negative impedance converter may be changed by as much as ±10% without appreciably influencing the properties of the filter. Synthesis was carried out for a whole system of filters of fourth- and sixth-degree with various minimum attenuations in the stop-band. The changes of all other elements are briefly considered and it is shown that the influence of all elements not determining the position of the transmission zero is less than the same relative change of the impedance converter constant.