A very small MMIC variable filter based on a new active filterdesign concept

摘要

A novel MMIC (monolithic microwave IC) active filter is proposedfor realizing a small-size variable bandpass filter with highselectivity at microwave frequencies. A second-order bandpass filterbased on the proposed design concept occupies a 1.2×1.3 mm3 area on the GaAs substrate. It is controllable for both qualityfactor Q, varying from 20 to 200, and a center frequency wider than 100MHz at the 1.3 GHz band. A fourth-order bandpass filter was alsofabricated by cascading two of the filter chips together. This isexpected to be a key device in the future development offrequency-variable equipment. The design concept, fabrication, andmeasured performance of the filter are described