Modeling and design of an ultra-miniaturized WLAN sub-system with chip-last embedded PA and digital dies

Abstract

System integration by die-embedding within electronic packages offers significant advantages in miniaturization, cost and performance for mobile devices. This paper presents the functional design and analysis of ultra-thin packages that combine embedded actives (GaAs Power Amplifier and a baseband digital IC) with embedded passives (band-pass filters), leading to an ultra-miniaturized WLAN sub-system. This chip-last design routes embedded dies in the outer build-up layer, using Embedded MEMS Actives and Passives (EMAP) technology being developed in the Georgia Tech PRC's industry consortium, as an alternative, lower cost approach over current chip-first and chip-middle methods. Electromagnetic (EM) simulations were performed in order to tune the electrical performance of interconnections based on die specifications and package configuration. The digital package was designed with multiple power-ground pair islands to enhance noise isolation, while improving overall signal and power integrity. The embedded module designs for RF transmitter and the baseband IC measure at 2.8mm × 3.2mm × 0.25mm and 10mm × 10mm × 0.25mm respectively, achieving over 4.5× volume reduction compared to existing wire-bond packages.