This article presents a 28 GHz switch and LNA chipset, and the RF front‐end module for 5G communication systems. The 28 GHz Single Pole Double Through (SPDT) switch and LNA MMICs are embedded in single RF front‐end module successfully using molding based embedded Wafer‐Level Package (eWLP) technology. For the low noise figure and high isolation, inductive source degenerated LNA topology and double shunt FET structure for SPDT switch are employed, and LNA and SPDT are implemented in single IC. The eWLP based package minimizes the parasitic component such as bond‐wire inductance and signals loss to enhance the performance of the RF front‐end module. At 28 GHz, the measured gain and noise figure of receiver path are 15.5 dB and 3.46 dB, respectively, and the IIP3 is +3 dBm at 45 mW power consumption.

This paper presents a compact and low-profile GaN power amplifier using interposer-based monolithic microwave integrated circuit (iMMIC) technology. The power amplifier based on iMMIC technology consists of a fully embedded discrete GaN HEMT power device in a silicon interposer with a cavity and several passive components such as resistors, inductors, capacitors, and transmission lines for matching networks using silicon integrated passive device (IPD) process. By adopting known good die and semiconductor process, this technology can improve yield and provide compact, low-profile solution compared to conventional hybrid MIC technology. Also, the standard silicon process can drive this solution to cost down compared to high cost GaN MMIC process. The size of the power amplifier using iMMIC technology is only 1.6 mm × 2.8 mm × 0.12 mm. The measured result shows that the iMMIC power amplifier has a P3dB of more than 37.7 dBm with a drain efficiency of 53% at 8 GHz. IntroductionRecently, GaN technology has been widely adopted in both commercial and military applications due to its high power density, wideband operation, high breakdown voltage, and so on. Especially, the development of GaN-based monolithic microwave integrated circuit (MMIC) technologies is one of the most exciting recent advances in microwave and millimeter-wave areas due to superior properties, internally matched structure, and very compact size [1]-[3]. Even though GaN MMICs have a high degree of integration and high performance, they suffer from high manufacturing cost. If passive components which occupies most areas in GaN MMIC are replaced with low-cost silicon integrated passive devices (IPDs), it can be another good low-cost and highperformance solution for realizing GaN-based circuits and systems.M. Camiade and C. Berrached et al. demonstrated quasi-MMIC technology based on passive GaAs MMIC with GaN power transistors [4], [5]. The matching networks are on GaAs substrate, and interconnection between GaN transistors and matching networks is done by wire bonding. This approach provides several key properties such as high integration, which is very close to MMIC dimensions, high design flexibility, and so on. An interposer-based MMIC (iMMIC) technology is proposed by C. Hillman et al. using a discrete GaAs pHEMT and a silicon interposer [6]. By embedding the discrete device in a recess below the surface of the silicon interposer wafer and allowing multiple metal layers for passive components, this iMMIC technology is MMIC-like approach.

This article introduces new packaging that improves the heat dissipation of RF power devices. Typically, power devices are mounted on a printed circuit board, in which the heat dissipation is made only through the bottom area of a device. The heat dissipation of the proposed structure is made through the bottom and side areas. As a result, proposed technology provides 30% improved heat dissipation in the RF GaN power amplifier. A copper sheet having a high thermal conductivity of around 400 W/mK is used as a core material to embed the power device. The measured results show that the drain efficiency of the fabricated X‐band power amplifier (PA) improved by about 13% in the proposed package structure.

This article presents an RLC matched power amplifier using quasi‐MMIC technology in the X‐band. The power amplifier consists of a GaN HEMT power device and several passive components including inductors, capacitors, resistors, and transmission lines using a silicon integrated passive device (IPD) process. The standard silicon process can drive the solution to cost down compared with conventional microwave monolithic integrated circuit (MMIC) technology. This technology using silicon IPDs provides small size matching networks close to MMIC dimensions. The input matching network using the RLC matched circuit is designed to obtain broadband characteristic and gain flatness. The dimensions of input and output silicon IPD are 1.5 mm × 1.2 mm and 1.9 mm × 2.2 mm, respectively, with a thickness of only 0.15 mm. The measured results show that the quasi‐MMIC power amplifier has a P3dB of more than 38.3 dBm with a drain efficiency of more than 51.2% in the frequency range from 8.2 to 10 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2803–2807, 2015

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