3D-SOP Millimeter-Wave Functions For High Data Rate Wireless Systems Using LTCC and LCP technologies

In this paper, the development of three-dimensional (3-D) millimeter-wave functions in multilayer low temperature cofired ceramic (LTCC) and liquid crystal polymer (LCP) technologies is presented for millimeter-wave compact and easy-to-design passive solutions for high data rate wireless systems. Both ceramic and organic technologies are candidates for the 3-D integration of system-on-package (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 LTCC patch resonator filter that uses vertical coupling overlap and transverse cuts as design parameters has been designed to achieve a high level of miniaturization and a great compromise between compactness and power handling. Excellent agreement between the simulation and the measurement has been verified for two operating frequency bands (58-60GHz/38-40GHz) of RF communications and sensors for applications such as wireless broadband internet or inter-satellite communications. A band pass filter has been fabricated on LCP substrate, offering a very simple, low loss flexible and low lost filtering solution for wideband millimeter waves applications such as 60 GHz WLAN short-range gigabit wireless systems. The design exploits the ripple near the cut off frequency of Tchebysheff low pass filter to create a band pass response and it exhibits the insertion loss as low as 1.5 dB at the center frequency of 60GHz and 3-dB bandwidth of 16.7 % (~10 GHz). Introduction Millimeter-wave (mmW) electronics for commercial applications, such as short-range broadband wireless communications and automotive collision avoidance radars, require low-manufacturing cost, excellent performance, and high level of integration. The multilayer LTCC System-OnPackage (SOP) approach is very well suited for these requirements because it offers a great potential for passives’ integration and enables microwave devices to be fabricated with high reliability, while maintaining the low cost [1]. The very mature multilayer fabrication capabilities of LTCC (εr=5.4, tanδ=0.0015) up to 100+ GHz enable the replacement of broadside coupling by vertical coupling and make LTCC a competitive solution to meet millimeter wave design requirements. As an alternative, Liquid Crystal Polymer (LCP) is an organic material that offers a unique low-cost all-in-one solution for high frequency designs due to its ability to act as both a high-performance flexible substrate (εr=2.9-3.0, tanδ=0.002-0.004) and a near-hermetic package for multilayer modules [2-4]. These characteristics make LCP very appealing for many applications and it can be viewed as a prime technology for enabling system-on-package RF and millimeter-wave (mmW) designs [2]. The choice of the most suitable technology depends on the application specifications such as environment, operation frequency, performance, volume and cost. In this paper, we present the development of various advanced 3-D LTCC and LCP system-on-package passive components enabling a complete passive solution for compact, low cost wireless front-end systems to be used in RF and mmW frequency ranges. The design of single-mode slotted patch filter with a transverse cut on each side has been presented to achieve compactness and great compromise between size and power handling. This filter has been embedded in LTCC and designed for two operating frequencies (58-60GHz/38-40GHz) of mobile communication systems. The paper clearly demonstrates how the physical dimensions of the miniaturized filter are determined by showing the simulated filter response as a function of critical design parameters such as the length of transverse cuts and the overlap distance between feeding structure and patch resonator. Also, a band filter has been designed to enable a low cost, very easy to design filtering solution to be integrated into a wireless millimeter-wave gigabit link system. The ripple of modified stepped impedance Tchebysheff low pass filters has been exploited and combined with a rejection centered at 60GHz. Insertion loss as low as 1.5 dB has been measured, demonstrating the potential of LCP for millimeter-wave applications. Patch Resonator Filter (59.3 GHz/39GHz) on LTCC Integrating filter on-package in LTCC multilayer technology is a very attractive option for RF front-ends up to mm-wave frequency range in terms of both miniaturization by vertical deployment of filter elements and reduction of the number of components and assembly cost by eliminating the demand for discrete filters. In mm-wave frequencies the band pass filters are commonly realized using slotted patch resonators due to their miniaturized size, their excellent compromise between size, power handling and easy-to-design layout [5]. In this section, the design of a single-pole slotted patch filter is presented for two operating frequency bands (38-40 GHz and 58-60GHz). All designs have been simulated