The design of maximally flat wideband amplifiers with double-tuned interstage coupling

Consideration is given to the realization of maximally flat amplitude responses of overall fractional bandwidths ranging from 30 to 150 percent, using mutually coupled double-tuned networks as coupling elements. No restriction on the Q of the coupled circuits has been imposed and design curves for determining the network parameters for any value of primary Q are included. These have been computed from a knowledge of the necessary pole distribution for the appropriate degree of flatness and bandwidth of the overall response. The effect of reducing the primary Q of a coupling network is discussed. The material presented is applicable to transitionally coupled double-tuned networks and maximally flat pairs, but the method can be extended to more general cases.