COMPACT DIPLEXER AND ITS IMPLEMENTATION FOR WIRELESS COMMUNICATION SYSTEMS

摘要

A new compact and effective lumped-element diplexer structure targeted for low-temperature co-fired ceramic (LTCC) implementation is proposed that can exhibit high levels of isolation between the low-pass and high-pass filters. Design equation formulations that take into account the isolation between two filters are presented. As an example, a diplexer for a dual-mode portable telephone for 900-MHz digital cellular and 1.9-GHzpersonal communication systems is designed and fabricated. According to the measured results, insertion losses within the passbands of low-pass and high-pass filters are both less than 0.5 dB, Minimum 20-dB rejection of low-pass filter at the passband of high-pass filter is achieved, and vice versa.