MICROWAVE CHANNELIZED ACTIVE-FILTERS - A NEW MODULAR APPROACH TO ACHIEVING COMPACTNESS AND HIGH SELECTIVITY

The new class of microwave active filters being presented offers a con venient way to realize miniature filter circuits with sharp passband-t o-stopband transitions. The approach, which lends itself to a broad ra nge of narrowband and wideband filtering applications, involves parall el connections of frequency-selective, unilateral network branches tha t contain both passive and active subcircuits. Highly selective filter ing action derives from controlled interferences among branch signal c omponents. Attributes of the new technique include unconditional circu it stability, tolerance for large passive-circuit-element losses, prac ticability of narrowband lumped-element configurations, graceful perfo rmance degradation with active element parameter changes, and the adva ntage of module-based procedures for design and implementation. The br oad applicability of the new approach is illustrated with three experi mental demonstration circuits that employ off-the-shelf MMIC amplifier chips. The circuits comprise a 10-GHz notch filter of one quarter per cent bandwidth, a 10-GHz bandpass filter of two percent bandwidth, and a 7.5-GHz lowpass filter.