University of L’Aquila Researcher Develops an Active Filter Design Methodology
Established in 1952 and located in L’Aquila, administrative center of the Abruzzo Region of Italy, the University is a public teaching and research institution offering a full range of academic programs, including biotechnologies, sciences, economics, engineering, education, humanities, medicine, psychology, and sport sciences. With seven departments, the University of L’Aquila offers its over 18,000 enrolled students 66 degree courses (divided between first and second level degrees), eight research doctorate programs, and specialization schools for master and vocational courses. Many members of its distinguished faculty of about 600 professors and researchers have received international recognition and are considered leaders in their fields of research.
The goal of Dr. Leonardo Pantoli, researcher at the University of L’Aquila, was to develop a methodology for designing high-quality active filters with tunable center frequency, low loss, high-dynamic range, and low-power consumption, all within a small footprint. His design approach for the realization of the active filters included an innovative configuration of the active section based on the use of an active inductor (AI) conceived with a single transistor that could be optimized for the target application taking into account the particular specs.
As an example, a high-order tunable filter was chosen to provide a feasibility demonstration of the proposed approach whereby each cell was composed of a shunt L-C cell and two series capacitances. The filter was centered at 1.95 GHz in agreement with the functional bandwidth of the chosen transistor. The -3-dB bandpass was 10 MHz, for a Q of approximately 200, with good input and output matching. The filter required less than 4 mA total bias current, for a power consumption of approximately 4 mW.
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