A LTCC cavity filter for MMW transceiver module application

A compact cavity filter using multilayer Low Temperature Co-fired Ceramic (LTCC) technology is proposed for millimetre-wave (MMW) transceiver module application. According to full-wave electro-magnetic (EM) comparing simulation, the length and the width of filter´s structure has been determined by optimizing and extracting quality factor and coupling coefficient of the cavity resonators. A Ka-band cavity filter of the proposed prototype is fabricated and measured. Measurement results show good performance and agree with EM full wave simulation. The minimum measured insertion loss is 2.21 dB at 34.4 GHz, and return loss is lower than 18 dB over the passband. The size of the filter is only 8.5 mm×3.2 mm×1.2 mm including microstrips I/O ports and via fences structure. The cavity filter exhibits advantages of small size and high reliability compared to conventional planar filter structure, which makes it suitable for MMW wireless communication applications.