SUMMARYA new systematic method for designing square-root domain (SRD) linear transformation (LT) filter is introduced in this paper. For this purpose, a substitution table containing the SRD LT equivalent of each passive element has been introduced. The proposed equivalents have been realized by employing appropriate SRD building blocks with low-voltage operation capability. As a design example, a 3rd-order SRD LT filter has been realized and its performance has been evaluated through simulation results. In addition, the most important performance factors of the SRD filter have been compared with those achieved by the SRD filters derived according to the leapfrog, wave, and topological emulation methods.

A novel n-th order Follow the Leader Feedback (FLF) multifunction low-voltage filter topology, realized by employing the concept of Square-Root Domain (SRD) filtering, is introduced in this manuscript. The realization of the SRD filter topology is achieved by utilizing the corresponding FLF conventional topology and performing a transposition into SRD, through an appropriate set of complementary operators. As a design example, a 5th-order SRD FLF filter has been designed and its performance has been evaluated through simulation results, where the most important performance factors have been considered.

Square-root domain universal biquad topologies are introduced in this paper. One of them is single input multiple output, while the other one is multiple input single output biquad. Important benefits offered by the proposed topologies are the electronic adjustment of the resonant frequency and the capability for operating in a low-voltage environment; also, the resonant frequency could be adjusted without disturbing the Q factor and vice-versa. Simulation results using the Spectre simulator of the Analog Design Environment of Cadence software validate the correct operation of the proposed topologies and provide important performance characteristics.