Advanced 3-D LTCC system-on-package (SOP) architectures for highly integrated millimeter-wave wireless systems

This paper reviews the development of advanced 3-D LTCC system-on-package architectures for compact, low cost wireless front-ends to be used in RF and millimeter-wave frequency ranges. Compact and easy-to-design passive circuits, such as filters and antennas, have hereby demonstrated great performance and high integration potential. The excellent performance of one patch resonator filter is verified through an insertion loss lower than 2.3 dB, a return loss larger than 18.2 dB over pass band, and a bandwidth about 6.4%. Also, experimental results of one directional filter show insertion loss of <3dB over the band pass section and a rejection similar to 25dB at around 38.5GHz over the band rejection section. LTCC design limitations have been overcome by using vertical coupling mechanisms to satisfy millimetre-wave design requirements. In addition, a double fed cross-shaped microstrip antenna has been designed for the purpose of doubling the data throughput by means of a dual-polarized wireless channel, covering the band between 59-64 GHz. This antenna can be easily integrated into a wireless millimeter-wave link system.