Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets

This work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 μm AlGaAs/InGaAs Depletion-Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die area of 3.2 mm2.

Electron-Beam Deposition of Aluminum Nitride and Oxide Ceramic Coatings for Microelectronic Devices

This work presents the results of the coating deposition by electron-beam evaporation of aluminum nitride and aluminum oxide targets in nitrogen and oxygen atmospheres in the forevacuum range (5–30 Pa). The method we employed is a combination of the electron-beam and plasma methods, since in the mentioned pressure range, the electron beam creates plasma that essentially changes the interaction picture of both the electron beam with the ceramic target and the flux of evaporated material with a substrate. We show a possibility of depositing such coatings on monolithic microwave integrated circuits passivated by Si3N4 dielectric.

Design and Optimization of Micro-Machined Sierpinski Carpet Fractal Antenna Using Ant Lion Optimization

This study investigates the optimized Sierpinski carpet fractal patch antenna and also explores the possibility of the integration of the proposed design with monolithic microwave integrated circuits. The optimization process has been performed using an ant lion optimization algorithm to achieve the required operating frequency and impedance matching. Further, due to surface waves excitation in the high index substrates used for the antenna design, the performance of the antenna degrades. Therefore, a process of micro-machining has been adopted to overcome this limitation. The micro-machining process creates an air cavity underneath the patch which further creates the low index environment in the patch antenna causing drastic improvement in the performance parameters along with the compatibility with monolithic microwave integrated circuits. The design shows multiple resonance frequencies in X-band and Ku-band. The proposed micro-machined design shows the resonance at 7.9 GHz, 9.6 GHz, 13.6 GHz, and 19 GHz with a maximum gain of 6 dBi.

Microstructure Characterization and Interfacial Reactions between Au-Sn Solder and Different Back Metallization Systems of GaAs MMICs

GaAs monolithic microwave integrated circuits (MMICs) with different back metallization systems (TiW/Au and Au/Ti/Au) exhibit different problems in the automatic Au-Sn eutectic bonding process, such as edge breakage or excessive voids. In this study, the formation mechanism of the edge breakage and excessive voids were investigated to prevent the damage of the MMICs in mass production scenarios. The microstructure and elemental distribution were studied using a scanning electron microscope and energy-dispersive spectroscopy. The void contents of the brazed region were measured with three-dimensional computed tomography. The top Au layer of the TiW/Au metallization partially dissolved in the melting An-Sn solder. Consequently, liquidus temperature of the solder increased, leading to isothermal solidification with the formation of ζ-Au5Sn in the scrubbing process, which was the reason for the edge breakage. The terminal Au film of the Au/Ti/Au metallization completely dissolved in the melting An-Sn solder. The metallurgical combination was achieved by the formation of the TiAu4 intermetallic compound between the Au-Sn solder and the Ti layer. The wettability of Au-Sn solder on Ti layer should be improved to prevent the formation of the excessive voids.

LINC Method for MMIC Power Amplifier Linearization

Background: This article proposes the design and implementation of a MMIC (monolithic microwave integrated circuits) Power amplifier using the ED02AH process. Methods: The MMIC ED02AH technology have been developed specifically for microwave applications up to millimeter waves, and for high-speed digital circuits. The use of a single branch of a power amplifier can produce high distortion. In the present paper, the Linear amplification with nonlinear components (LINC) method is introduced and applied as a solution to linearize the power amplifier, it can simultaneously provide high efficiency and high linearity. To validate the proposed approach, the design and characterization of a 5.25 GHz LINC Power Amplifier on MMIC technology is presented. Results: Good results have been achieved, and an improvement of about 37.50 dBc and 59 dBc respectively is obtained for the Δlower C/I and Δupper C/I at 5.25 GHz. Conclusion: As a result of this method, we can reduce the Carrier Power to Third-Order Intermodulation Distortion Power Ratio. Excellent linearization is obtained almost 37.6 dBc for Δlower C/I and 58.8 dBc for Δupper C/I.