The term: “Automated Parameter Synthesis” (APS) as used by Nuhertz Technologies, refers to the technique of synthesizing the response of a Bandpass filter by direct manipulation of the pole and/or zero characteristics of a filter network’s transfer function*, via manual manipulation or direct synthesis, and sometimes recalculating the pole positions required to restore the maximally flat, equiripple, or constricted equiripple characteristics of the pass band, for both frequency symmetrical and asymmetrical functions. The technique represents a major increase in the efficiency of the filter itself. The circuit is realized with a reduced number of physical components.
As embodied, the APS interface may use manual sliding zeros to move stopband zeros. The technique allows the results to indicate the appropriate L and C values directly. In FilterSolutions™, software, passband response is driven by synthesis around arbitrary “stopband” zeros which are used to calculate reflection zero positions, subsequently shaping the passband to a maximally flat, equiripple, or constricted equiripple function.
FilterSolution’s constricted equiripple function automatically constricts equiripple to a percentage of the stop bands and/or pass bands by direct synthesis, shaving significant time over manual placement of stopband zeros and reflection zeros. The Automated Parameter Synthesis technique is closely related to the well known FilterSolutions technique of delay equalization using quadruplet zeros. In that technique, the stopband is shaped around off-axis stop band zeros (quadruplet zeros) to alter group delay, while maintaining equiripple or other shape responses. In both techniques L and C values are calculated directly from the transfer function.
* The transfer function describes the filter’s response characteristics (input and output dynamics), as a ratio of two polynomials. The poles and zeros refer to the real coefficients of the numerator and denominator of the function.