Abstract:Filter plays the role of a selected pass band and channel in wireless communication system, which is able to filter out harmonic and suppress stray. With the development of the electronic system integration, the planar coupling filter is too large and flat to adapt the requirements of miniaturization,light weight in the modern wireless mobile communication system.A laminated strip line adjustable electric filter based on low temperature co firing ceramic ( LTCC ) technology was designed. Using the principle of the broad brimmed coupling , the size of the filter decreases by more than 50% compared with the traditional electric adjustable filter. Due to the laminated structure, the filter could produce a transmission zero at each side of band pass filter to get higher degree of restraint outside the band. The center frequency of the laminated strip line filter was 2.4 GHz with tuning range of 2.1~2.7 GHz.The voltage standing wave ratio in the frequency band was less than 1.25, the insertion loss was less than 1.3 dB,the size was only 4.8 mm×4.5 mm×0.6 mm, which could fulfill the requirement of the miniaturization and high performance at the same time.