Advanced System-on-Package (SOP) Front-End Passive Solutions for RF and Millimeter-Wave Wireless Systems

In this paper, we present novel three-dimensional (3-D) compact and easy-to-design passive solutions (filters/duplexers, antennas, couplers) using system-on-package (SOP) multilayer low temperature cofired ceramic (LTCC) and organic (Liquid Crystal Polymer (LCP)) technologies in RF and millimeter-wave wireless systems. Both ceramic and organic technologies are candidates for the 3-D integration of system-onpackage (SOP) miniaturized RF/microwave/millimeter-wave systems. LTCC has been widely used as a packaging material because of its process maturity/stability and its relatively high dielectric constant that enables a significant reduction in the module/function dimensions. As an alternative, LCP is an organic material that offers a unique combination of electrical, chemical, and mechanical properties, enabling high-frequency designs due to its ability to act as both the substrate and the package for flexible and conformal multilayer functions. A compact LTCC single-mode patch resonator filter utilizing vertical coupling overlap and transverse cuts as design parameters has been designed at operating frequency band of 58-60GHz. Then, a compact transmit/receive duplexer (39.8GHz/59GHz) has been realized by the noble 3D deployment of the presented single-mode patch resonators to provide low insertion loss and high channel-to-channel isolation. A double fed cross-shaped microstrip antenna has been designed for the purpose of doubling the data throughput by means of a dualpolarized wireless channel, covering the band between 59-64 GHz. This antenna can be easily integrated into a wireless millimeter-wave link system. Finally, a new architecture concept intended for reconfigurable couplers is proposed. The device has been fabricated and tested in microstrip technology at 5 GHz. The novel concept introduced is independent of the used technology; a multilayer 35 GHz version in LCP substrate, meant to be used with MEMS switches, has also been designed and simulated. Index Terms – patch resonator, duplexer, low-temperature cofired ceramic (LTCC), intelligent system-on-package (SOP), 3D/vertical integration, microstrip antenna, millimeter-wave (mmW), reconfigurable coupler, MEMS.