Application of direct synthesis techniques to customize filters with complex frequency response

Recently, direct synthesis techniques (DSTs) have been presented for filter synthesis. Unlike conventional synthesis techniques, DSTs derive the filtering polynomials of the filters to be synthesized directly in their own frequency domain. These filtering polynomials are real coefficient so that they might find applications in various fields. Furthermore, DSTs might be used to customize filters with a more complex frequency response, such as asymmetric frequency response or multi-band frequency response. In this paper, DSTs are compared with some well-known filter synthesis techniques. Then, the application of DSTs in the design of lumped-element LC filters, distributed-element filters, active RC filters, and infinite impulse response digital filters with complex frequency response is discussed. Some examples are presented for demonstration. Copyright (C) 2015 John Wiley & Sons, Ltd.