CAD of microwave integrated multistage active filters by the real frequency method

This paper presents results of synthesis and optimization for active and integrated microwave filters. The method is based on the real frequency theory. The gain, bandwidth, VSWR and group delay are the optimized characteristics. Optimization is done with the More (1978) subroutine which is an improvement of the Levenberg-Marquardt algorithm. These integrated active low-pass and bandpass filters are used in the field of telecommunications. Applications are given with one or several FET, several equalizers and attenuation poles which are necessary for filters. Lowpass and bandpass examples are given in microwave domains. The responses of filters can have an asymmetric frequency characteristics. A CAD program has been written and named FREELCD. We give the different subroutines and show that FREELCD is useful for microwave integrated active filters.