120-GHz Tx/Rx Waveguide Modules for 10-Gbit/s Wireless Link System

A new super-thin power amplifier (PA) module has been developed for W-CDMA mobile handsets. The PA module consists of an InGaP/GaAs HBT MMIC and a 50-Ω output matching circuit on polyimide film, which is the first application of such film as a PA module substrate. The key features of the PA substrate are thinness, low thermal resistance, and low cost. As a result, the PA module is only 6.0 x 6.0 x 0.8 mm3 (0.03cc) and meets the specifications of W-CDMA with a high power-added efficiency (PAE) of 43%, a gain of 27 dB, and an adjacent channel leakage power ratio (ACLR) of -36 dBc at an offset frequency of 5 MHz at a Pout of 26 dBm under a supply voltage of 3.5 V with 3.84 Mcps HPSK modulation.

Effect of voids on thermomechanical cracking in lead-free Sn3Ag0.5Cu interconnections of power modules

In this paper, the reliability of RF power transistors’ solder attachments is characterized through experiments and simulations. Test cases consisted of power amplifier (PA) modules on AlSi10Mg substrates with either a low or high mutual thermal mismatch. The module’s flange interconnections were stressed by means of thermal cycling testing (TCT) in the 15 °C–95 °C range. Scanning acoustic microscopy (SAM) was used intermittently to inspect the interconnections of selected structures during cycling breaks. Optical cross-polarization microscopy and scanning electron microscopy were used in the failure analysis of the solder joints. Different materials and dimensional variations were tested in simulations to observe differences in thermal stress. The viscoplastic behavior of lead-free solder in the interconnection was modeled using Anand’s constitutive equations. The first cracks could be observed with SAM after 100 cycles. SAM imaging showed that in the worst case, 72% of the interconnection area had cracked at the end of the 1100-cycle TCT. Only a marginal amount of cracks could be observed in PA modules with a better coefficients of thermal expansion match to the substrate. Simulations indicated that it is possible to decrease creep energies significantly and thereby increase the lifetime expectancy of interconnections by selecting the correct materials and structures.

A highly integrated multi-mode multi-band (MMMB) power amplifier module (PAM) using hybrid bulk complementary metal oxide semiconductor (CMOS), gallium arsenide (GaAs) heterojunction bipolar transistor (HBT), and silicon-on-insulator (SOI) technologies for low band (LB, 824–915 MHz) and high band (HB, 1710–1980 MHz) is proposed. The hybrid MMMB PAM integrates a bulk CMOS controller die, a GaAs HBT power amplifier (PA) die and a SOI switch die on a six-layer laminate. To simultaneously obtain both highly efficient and highly linear characteristics over a wide range of input power levels, a parallel dual-chain PA strategy has been adopted to provide vary bias current and gain for low-power mode (LPM) and high-power mode (HPM) operation. Additionally, a broadband two-section low-pass output matching network design based on the suppression of high-order harmonics is proposed for enhanced efficiency and linearity. In order to achieve further miniaturization, a three-dimensional (3D) die stack multi-chip module (MCM) packaging structure, where the presented CMOS controller die is stacked vertically on the GaAs HBT PA die, is implemented. The measurement results show that the fabricated MMMB PAM achieves 26.1–27 dB of power gains and 38–38.4% of PAEs at an output power (Pout) of 28 dBm in the HPM, and 20.4–20.9 dB of power gains and 12.4–13.8% of PAEs at Pout of 17 dBm in the LPM over LB. For HB, power gains of 24.3–26.7 dB while maintaining PAEs of 38.2–39.9% at Pout of 28 dBm, and power gains of 15.9–17.5 dB while maintaining PAEs of 12.3–12.8% at Pout of 17 dBm are realized in the HPM and LPM, respectively. The fabricated PAM covering five frequency bands and operating at two power modes only occupies a 5 × 3.5 mm2 area. To the best of the authors’ knowledge, this work is the first demonstration of a MMMB PAM adopting an ultra-compact 3D vertical stack MCM package with favorable RF performance.

A new practical reconfigurable output network for a multiband reconfigurable power amplifier (PA) is proposed for universal mobile telecommunications system (UMTS) handset applications. The proposed reconfigurable network can reconfigure the output power and the output path, as well as the frequency. It consists of a power-reconfigurable network, a frequency-reconfigurable network, and a path-selection network. In this paper, its reconfiguration principle is described to extract key design parameters for the reconfigurable PA implementation. To demonstrate the performance of the proposed structure, a 5 mm × 6 mm multiband reconfigurable PA module is developed for UMTS high- and low-frequency band application. The fabricated PA module can cover any three bands out of five popular high- and low-frequency UMTS bands. To enhance the efficiency during low output power operation, the authors' stage-bypass technique is also employed. The fabricated PA module showed adjacent channel leakage ratios better than -39 dBc up to the rated linear output power and power-added efficiencies of higher than 39% at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">out</sub> =28 dBm over all the UMTS frequency bands. Efficiency degradation was limited to less than 2% compared to the single-band PA. Measured RF performance of the reconfigurable PA validates the usefulness of the proposed reconfigurable structure for multiband UMTS applications.

A high performance and low power 2.4 GHz radio frequency (RF) transmitter for biomedical application is presented. The design utilizes LC voltage control oscillator (VCO), ASK modulator, and an inverse Class-D (D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) power amplifier (PA). The ASK modulates the carrier signal generated by a low phase noise LC-VCO, then the modulated signal is amplified by the inverse Class-D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> PA. The proposed RF transmitter achieves -11.14-dBm output power with 3.88% efficiency. It also supports 130-Mb/s data rate and consumes 1.98-mW. The design has been implemented in a 0.13μm CMOS process technology and fully integrated on-chip.

Based on an analog-gain control bias circuit (AGBC), a dynamic and fixed bias-controlled InGaP/GaAs HBT MMIC power amplifier module (PAM) is designed for code-division multiple-access (CDMA) and advanced mobile-phone service (AMPS) handset applications. The proposed AGBC effectively improves the power-added efficiency (PAE) of a power amplifier (PA) over a wide range of output power while satisfying the CDMA/AMPS linearity requirements. The PA gain slope with respect to AGBC mode-control voltage is about 12 dB/V. The measured average current of this AGBC PA is reduced by 64% compared to a standard PA. The AGBC PA exhibits a 28 dB power gain, a 45% PAE, and a -49 dBc adjacent channel power ratio (ACPR) at 28 dBm output power with a fixed mode-control voltage.

In this article, in order to enhance the linearity of power amplifier modules (PAM), we have suppressed the harmonics at the output port of a high‐power amplifier (HPA) and cancelled the third‐order intermodulation distortion (third IMD) by a predistortion scheme. The matching network to suppress the harmonics consists of metamaterial like the composite right/left‐handed structure. Both the second and third harmonics are suppressed over 27 dBc. A phase of generated third IMD at the output of the drive amplifier has changed in order to offset the third IMD of HPA. The harmonics of the proposed PAM suppresses over 6 dB more than a single HPA and over 20 dB more than a reference power amplifier. The PAM has 37 dBm of output power and 21.6 dB of power gain. The second harmonic and third IMD are −53 and −42.5 dBc about PAM, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1497–1500, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27625

A set of W-band power amplifier (PA) modules using monolithic microwave integrated circuits (MMICs) have been developed for the local oscillators of the far-infrared and sub-millimeter telescope (FIRST). The MMIC PA chips include three driver and three PAs, designed using microstrip lines, and another two smaller driver amplifiers using coplanar waveguides, covering the entire W-band. The highest frequency PA, which covers 100-113 GHz, has a peak power of greater than 250 mW (25 dBm) at 105 GHz, which is the best output power performance for a monolithic amplifier above 100 GHz to date. These monolithic PA chips are fabricated using 0.1-/spl mu/m AlGaAs/InGaAs/GaAs pseudomorphic T-gate power high electron-mobility transistors on a 2-mil GaAs substrate. The module assembly and testing, together with the system applications, is also addressed in this paper.

In this article, a polarization-diversity technique multiple-input multiple-output (MIMO) is demonstrated to double the spectral efficiency of a line-of-sight quadrature phase-shift keying (QPSK) wireless link at 220-255 GHz with a pair of highly integrated single-chip transmitter (TX) and receiver (RX) front-end modules in 0.13-μm SiGe HBT technology ( f T/ f max = 350/550 GHz) exploiting only a low-cost wire-bonded chip-on-board packaging solution for high-speed baseband (BB) signals. Both TX and RX chips accommodate two independent fundamentally operated direct-conversion in-phase and quadrature (IQ) paths with separately tunable on-chip multiplier-based (×16) local oscillator (LO) generation paths driven from a single external highly stable 13.75-16-GHz frequency synthesizer. On the RX side, a mixer-first architecture is implemented to improve the symmetry between upper and lower sidebands (USB and LSB) at the cost of an increased noise figure (NF), whereas, on the TX chip, each upconversion mixer is followed by a gain-bandwidth (BW)-limited fourstage power amplifier (PA) to support the link budget at a meter distance. Next, two independent IQ data streams from the upconversion/downconversion paths on each chip are directed to a common lens-coupled broadband on-chip slot antenna system. This way, two orthogonal circular polarizations [left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP)] can be transmitted with sufficient isolation for link operation without the need for a high-speed depolarizer in the BB for any relative orientation between TX and RX modules. The antenna combined with a 9-mm diameter Si-lens provides a directivity of 23.5-27 dBi at 210-270 GHz for each of the modules. This, along with a peak radiated power of 7.5 dBm/ch from the TX module, and the cascaded conversion gain (CG)/single sideband (SSB) NF of 18/18 dB/ch for the RX module followed by a broadband amplifier (PSPL5882) from Tektronix allowed successful transmission of two independent QPSK data streams with an aggregate speed of 110 and 80 Gb/s over 1 and 2 m, respectively, at 230 GHz with a board-level limited channel BB bandwidth (BW) of 13.5 GHz.

Envelope tracking (ET) prolongs the battery life by modulating the supply of a power amplifier (PA) according to the signal envelope. With this emerging technology, the PA efficiency is greatly improved, whereas the supply modulator (SM) itself needs to provide efficient and accurate envelope tracking for the overall performance of the SM-PA combined system (PA module). The ET technique, meanwhile, has seen limited use in high-power transmission due to the reduced SM efficiency for low output power originating from the linear stage in hybrid structures [1].

A hybrid power amplifier building block and a power amplifier module from 2 GHz to 6 GHz were designed, fabricated and measured. These power amplifiers are all based on AlGaN/GaN HEMT technology. The future applications for these types of power amplifiers are mainly electronic warefare (EW) applications. Novel communication jammers and especially active electronically scanned array EW systems have a high demand for broadband high power amplifiers. Output power levels with a peak value of 90 W at lower frequencies and more than 40 W up to 6 GHz are measured. With these power amplifiers novel EW system approaches can be investigated.

This paper presents a low power Gaussian Frequency-Shift Keying (GFSK) transceiver (TRX) with high efficiency power management unit and integrated Single-Pole Double-Throw switch for Bluetooth low energy application. Receiver (RX) is implemented with the RF front-end with an inductor-less low-noise transconductance amplifier and 25% duty-cycle current-driven passive mixers, and low-IF baseband analog with a complex Band Pass Filter(BPF). A transmitter (TX) employs an analog phase-locked loop (PLL) with one-point GFSK modulation and class-D digital Power Amplifier (PA) to reduce current consumption. In the analog PLL, low power Voltage Controlled Oscillator (VCO) is designed and the automatic bandwidth calibration is proposed to optimize bandwidth, settling time, and phase noise by adjusting the charge pump current, VCO gain, and resistor and capacitor values of the loop filter. The Analog Digital Converter (ADC) adopts straightforward architecture to reduce current consumption. The DC-DC buck converter operates by automatically selecting an optimum mode among triple modes, Pulse Width Modulation (PWM), Pulse Frequency Modulation (PFM), and retention, depending on load current. The TRX is implemented using 1P6M 55-nm Complementary Metal–Oxide–Semiconductor (CMOS) technology and the die area is 1.79 mm2. TRX consumes 5 mW on RX and 6 mW on the TX when PA is 0-dBm. Measured sensitivity of RX is −95 dBm at 2.44 GHz. Efficiency of the DC-DC buck converter is over 89% when the load current is higher than 2.5 mA in the PWM mode. Quiescent current consumption is 400 nA from a supply voltage of 3 V in the retention mode.

RF transistors can be found in several present day electronics including mobile radio and telecommunication applications, TV & radio broadcast, avionics, radar and defense communications as well as industrial, scientific, medical (ISM) and broadcast applications. The increasing demands for data anywhere/anytime (mobile internet) requires increased deployment of wireless communication infrastructure. This has pushed upwards across the supply chain (suppliers and customers alike). At the core are RF power amplifiers (PA) with a very costly design, hence important to get it right as rework may not be possible. The assembly of RF power transistors in PA modules is the back-bone of these applications. Such modules are usually generating high power (> 100 watts) with different package outlines and lead configuration. The high power demands excellent thermal management, else product performance and lifetime (reliability) are compromised. As a consequence, the transistors are often packaged in "chunky" S OT outlines, with a cerami c/plastic body and a metal flange. Packaging such RF power modules (or PA) has historically been achieved with bolt down devices, where only the leads of the components were soldered (more akin to manual assembly operations). A thermal compound was used underneath the transistor. High volume assembly is a basic capability (with automation a necessity) to meet industry demand. There are a variety of issues to consider module assembly since there are strong interplay between design, materials and process in order to achieve the desired performance (electrical, thermal, mechanical, and reliability). Due to thermal management requirement, the transistors are normally soldered directly onto the pallet (laminate bonded onto a heat sink) with the leads and SMDs on to the laminate on the pallet. Base on the SOT outline (i.e. gull wing), a cavity or pedestal is required in the pallet with a cut-out in the laminate. Each PA module will be different in i.e. size, weight, materials, number of transistors, board construction with no two modules the same. With such spectra of possibilities in the module design and permutations on assembly processes, the paper outlines and addresses the key issues to consider and approach to achieve robust PA modules assembly. It includes but not limited to substrates, solders, heat sinks, plating, board design and reflow soldering (assembly process flow). Key to achieving the robust assembly process is an iterative approach with feedback at each step in the process including a modeled reflow profiling. In addition, a novel use of Rth (thermal impedance) in combination to acoustic microscopy / x-rays to assess the quality of the soldered interface is presented. The solder volume is key to accommodate manufacturing tolerances and solder joint reliability. Additionally, the issues presented constitute a "toll-box" for PA module assembly, including microwave pallet modules with matched input/output impedance.

A new power amplifier module (PAM) in which GaAs power MESFETs are mounted directly on an aluminum nitride (AIN) substrate has been developed for analog cellular phones. This module occupies a volume of 0.2cc, only 1/4 as large as that of conventional one, and can deliver an output power (Pout) of 31dBm with a power-added efficiency (PAE) of 58% at a low operating voltage of 3.5V around 900MHz band. Furthermore, a new microwave probe card has been introduced into on-wafer RF power measurement of the FETs in order to improve the yield of the PAMs. Using this probe card, the maximum output power of 30.9dBm has been obtained, and gain deviation between on-wafer and packaged FETs is only 1.4dB. This new concept PAM and the developed on-wafer measurement technique must promise advanced high-performance PAM.