A new high isolation lumped-element 180º hybrid, using electronically adjustable filters with varactor diodes, are proposed. This design is very simple and is based on only two configurable low order (N = 2) filters. Due to the limited tuning frequency range of varactor diodes, maximum near-octave frequency coverage of 2.5-5 GHz was planned in the high isolation hybrid. An impressive simulated typical isolation in the range of >60dB was achieved. One of the typical applications of developed hybrids could be the conversion of 70MHz IF to microwave frequencies, with broadband mixers in single-conversion converters, and with very high LO rejection (>60 dB).
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