A 1.26-3.3 GHz Tunable Triplexer With Compact Size and Constant Bandwidth

In this letter, a novel tunable triplexer is proposed with very compact size and constant fractional bandwidth. The proposed triplexer employs very simple filter prototypes, and can continuously cover a wide frequency tuning range from 1.26 to 3.3 GHz. Each filter channel in the triplexer can be independently controlled without affecting others, and exhibits a constant fractional bandwidth during frequency tuning. The insertion loss varies from of 2.8-6.6 dB with silicon varactors. Simulations and measurement are presented with excellent agreement. Application areas are in multi-standard communication systems.