Design and Implementations of RF Systems and Sub-systems in LCP-type Multilayer Technology

Abstract

Miniaturization and data throughput are key driving factors in the growth and deployment of wireless LAN (WLAN) networks. This paper presents a novel LCP-based organic packaging technology for implementation of RF systems and sub-systems. Examples shown include lowprofile baluns, bandpass filters and front-end modules (FEM) for 802.11a/b/g and 802.11n applications. IntroductionIncreasing system complexity, combined with a drive towards a reduction in size, has powered the need for higher levels of integration [1]. High Q passives embedded in LCP based organic substrates ([2]-[4]) provide a combination of high levels of integration with reduction in size, compared to current PWB-with-discrete elements, thin-film or Low Temperature Cofired Ceramic (LTCC) solutions.This paper describes the development of integrated passive devices (IPD) and front-end modules (FEM) for WLAN (802.11b/g, 802.11 a/bg) applications. The key features include: 1) Low overall thickness in the order of 1mm to 1.5mm. This includes multilayer substrate, die and overmold to achieve total thickness, 2) Flexibility in embedding components such as multiplexers, duplexers, filters, baluns, and couplers in a reduced number of layers compared to LTCC. This feature is enabled by using photolithography techniques allowing for 2mil (50um) lines with 2 mil spacing.3) High Q inductors and capacitors achieved by using thick low-loss LCP laminate (loss tangent in the range of 0.0015 to 0.002) and thick conductors (as thick as 1Oz.) 4) High reliability because of near hermetic properties of the multilayer laminates with moisture absorption less than 0.04% 5) Fully shielded parts for minimizing the electromagnetic interference.The paper is organized as follows. Section 1 presents the design of IPDs using lumped-element approximations. A low profile lattice-type balun is shown as an example. Section 2 covers stacked IPDs, and shows the design and implementation of a 3-pole bandpass filter. Finally, Section 4 presents the implementation of a dual-band FEM for dualband MIMO based WLAN systems.