Chip Scale Review - January February 2020

4 Chip Scale Review January • February • 2020 [] 6GHz frequencies, that means an antenna tuner is increasingly becoming a key component. At millimeter wave frequencies, however, AiP and antenna-on-package (AoP) comes into play. At millimeter-wave frequencies, antenna size reaches the RF integrated circuit’s (RFIC) form factor. In addition, RF losses are such that integrating the antenna along with the RFIC is no longer an option, it is now mandatory. 5G mmWave has democratized AiP technology AiP is a relatively new concept that has already made its way to the market. The most notable example is Samsung’s flagship phone, the S10 5G commercialized in the US market for Verizon’s 5G ultra- wideband (UWB) subscribers. The device currently supports 26, 28 and 39GHz bands thanks to the combination of a baseband processor (X50M) along with three AiP modules (QTM052) integrated into the phone case. Two generations of AiP have been used for this phone [6]. The first one, as shown in Figure 2 , features a PMIC, several passive components, and a transceiver on the bottom side of the PCB. The transceiver is connected to two types of antennas through the package laminate substrate. The first type of antenna consists of eight dipoles embedded in the layer of the laminate substrate and isolated from the transceiver by a compartment shielding. ny wireless system requires antennas to conver t the electric energy into radio waves traveling through the air. Whether it is for wireless sensing or broadband communication between at least two points, multiple types of antennas have been developed depending on the targeted application. Monopole, dipole, yagi, dish, patch, etc., are some of the existing configurations. Recently, a new type of system configuration, called antenna in package (AiP), has appeared and is becoming more and more popular, at least in the consumer market. In this article we will review the market drivers and the state of the art, as well as the market potential for AiP. Advanced packaging: innovation for consumer connectivity apps In the consumer market, the main technology deployed for cellular and Wi- Fi connectivity is based on relatively low f requencies, the so-called sub- 6GHz frequency range. Because of the sparse and poor spectrum holding from network providers, complex technologies such as carrier aggregation and multiple- input multiple-output (MIMO) have been deployed to comply with the never-ending increasing demand for data consumption. In the meantime, RF board allocation has shrunk in the mobile handset because of restricted space with a larger battery size and new features added. This strategy has put pressure on RF front-end module makers and outsourced semiconductor assembly and test (OSAT) companies to develop very complex packaging technologies. An example of dense RF component integration is shown in Figure 1 . The Apple iPhone ® Xr features one or another module for dual-sourcing reasons (shown in Figure 1 ). Both modules are pin- to-pin compatible and include all necessary RF components: acoustic wave filters (in red), RF switches (in green), a power amplifier (in purple), a low-noise amplifier (in yellow) and a power management integrated circuit (PMIC) (in blue). Because two different frequency domains (mid band and high band) are utilized in this device, complex electromagnetic interference (EMI) shielding techniques have been employed to isolate the different bands. In Qorvo’s module, EMI shielding is using the package laminate substrate with a ground trace, whereas Broadcom uses grounded palladium-coated copper (PPC) wire bonded onto critical components to be protected. As RF component integration density is still increasing, the latest RF system-in-package (SiP) modules found in the Apple iPhone ® 11 now come in double-sided ball grid array (BGA) packaging with EMI shielding [3]. For low-end smartphones, where cost is more important than the form factor, the mainstream packaging is SiP using long grid array (LGA) [4,5]. In fact, the iPhone ® 11 still is an advanced LTE phone. With the 5G roll out, the densification trend of RF components in a mobile handset will extend to sub-6GHz frequencies. But the story is different for 5G mmWave applications. In the sub-6GHz world, antenna integration is not possible on account of the size and location of the antenna. Instead, antennas are connected to the modules with a coaxial cable, printed circuit board (PCB) or flex PCB. A basic requirement for the consumer market is that, whenever possible, antenna size needs to be shrunk down to comply with the stringent system integrator requirements. For sub- A Figure 1: State of the art of the 4G and Sub-6 RF Layout; Qorvo QM76018 (left) [1] and Broadcom (AFEM-8092) (right) [2]. SOURCES: [1,2] Antenna in package (AiP): disrupting wireless communication and HMI By Stéphane Elisabeth [System Plus Consulting] , Cédric Malaquin [Yole Développement] , both part of the Yole Group of Companies TECHNOLOGY TRENDS