Power Module Interconnection Reliability in BTS Applications

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

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.

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

This paper describes the development of wavegude modules for 120-GHz wireless applications. The MMIC in the modules were fabricated using 0.1-mum-gate InP-HEMTs and coplanar waveguides. The transmitter (Tx) module contains a Tx MMIC and a multiplier MMIC for carrier generation. The Tx MMIC contains a frequency doubler, ASK modulator, and an amplifier. Output power of the Tx module is 0 dBm. The receiver (Rx) module contains a Rx MMIC with a low-noise amplifier and ASK demodulator. For high-power operation of transmitter, we developed a power amplifier (PA) waveguide module that attaches to the Tx module. This PA module contains one-chip PA MMIC, and has 13-dBm output power with associated gain of 10.5 dB at 125 GHz. A back-to-back test of the Tx/Rx modules with and without the PA module have shown it to be fully functional at 10-Gbit/s data rate with BER = 1e-10 at -34.5-dBm and -36.1-dBm input powers for the receiver, respectively

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 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 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.

A compact power amplifier module (PAM) integrated with a power detector utilizing low temperature co-fired ceramic (LTCC) technology is presented for the IEEE 802.11a/b/g, GPRS and WCDMA applications. All MMICs' matching circuits were fabricated with the input and inter-stage matching circuits realized on-chip so that the PAM size is significantly reduced. The output matching circuit was implemented on an LTCC substrate to reduce power loss based on the advantages of high-Q ceramic components. The proposed PAM provides high power added efficiency and good linearity. Moreover, the measured results indicate the excellent performance of this PAM

In this paper, the recent advances of CDMA power amplifier module developments for wireless handset applications are reviewed. Technology choices among GaAs, SiGe and PHEMT for linear PA designs are compared. The trade-offs of circuit design and module approaches are discussed in detail. The measured performances of some representative state of the art power amplifier modules are presented. The high integration of more front-end components and functionalities into the power amplifier module and the increasing demand for high linear efficiency at lower output power has become a widely acceptable trend.

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.

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.

A K-band power amplifier (PA) module with on-chip input and output matching network was fabricated in standard 130-nm CMOS process with 1.5-V supply voltage. The fully integrated PA module consists of 2-stage pseudo-differential cascode configuration PA and on-chip stacked balun based on transformer. At 26GHz, the PA achieved 18.6-dB small-signal gain, 12.2-dBm saturated output power and 22.4% power added efficiency (PAE). The chip occupies an area of 0.88 × 0.62mm2, including all the dc and RF pads.

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.

This work describes a dynamic power supply method for improving power amplifier efficiency. The proposed band limited dynamic supply control (BLDSC) processes the envelope of transmitting signal into a bandwidth limited supply control signal. With the aid of a switching mode DC-DC convertor, the processed control signal can be reconstructed to the supply terminal of power amplifier (PA) for reducing supply voltage at low output level. The proposed configuration is hardware efficient and improves the efficiency of PA without sacrificing the input signal bandwidth. A power amplifier module is realized and tested using the 10MHz WiMAX standard. Experimental results show a maximum 50% DC power consumption reduction under 10MHz signal bandwidth.

ABSTRACTIn this paper, the design theory of hybrid continuous mode (HCM) power amplifier (PA) with more general input nonlinear effect is deeply studied. By analyzing the change of asymmetric conduction angle caused by the arbitrary amplitude and phase of the input nonlinear second harmonic, a more general time domain waveform of drain voltage and current of HCM PA can be derived. The load design space is reconstructed by the new time domain waveform of drain voltage and current. The analysis shows that using arbitrary input nonlinearity can provide more flexible input harmonic impedance space in broadband design, which can maintain and improve the performance of broadband PA. Then, an improved T‐type input harmonic control matching network is proposed to control the input nonlinearity more effectively. Finally, for the practical validation of the proposed theory, a broadband hybrid continuous‐mode PA operating at 1.8‐ to 3‐GHz is designed by using a commercial 10‐W GaN high electron mobility transistor (HEMT). The measured results show drain efficiency reaches 65% to 72.6% at saturation, 11.9‐ to 14.2‐dB gain and 40.3‐ to 42.2‐dBm saturation output power.