MICROWAVE, BIQUADRATIC, ACTIVE-RC FILTER DEVELOPMENT

We present a number of computer-simulated results for a recently devel oped family of active-RC, microwave, biquadratic filters. These circui ts are gyrator-based on contain negative second-generation current con veyors (CCII-s) realized as cascades of MMIC GaAs FETs. First, the cir cuit family is extended to include asymmetric band-reject filters. As with the previous circuits of the group, we use optimization to obtain an accurate frequency response when the CCII-s are implemented as cas caded pairs of GaAs FETS. Second, we illustrate know cascades of three or four devices become necessary for the CCII-s of bandpass biquads a s their center frequencies are increased. Next, we show how third- and fourth-order filters may be obtained by cascading optimized lower-ord er sections. In our examples, the slight interaction between the stage s is eliminated by adjusting a single element. Finally, we discuss the topological origins of the biquad family and consider alternative cir cuit structures which may possess particular practical advantages. (C) 1998 John Wiley & Sons, Inc.