X 波段四通道MMCM 基板设计

低温共烧陶瓷（LTCC）是制作微波多芯片组件（MMCM）基板的理想材料。本文介绍了基于LTCC 工艺的微 波传输线、集成腔体、功分器和散热过孔的设计。对于多通道微波组件,采用带状传输线和腔体结构有利于实现通道 间的高隔离度,集成功分器和浆料电阻有利于实现组件的小型化并可获得较好的微波性能,而矩阵散热过孔可以显著 改善基板导热性能,满足小功耗器件的散热要求。     

Thermo-mechanical reliability analysis of a RF SiP module based on LTCC substrate

The RF SiP module based on LTCC substrate has attracted considerable attention in wireless communications for the last two decades. However, the thermo-mechanical reliability of this 3D LTCC architecture has not been well-studied as common as its traditional ceramic package structure. A practical RF SiP module based on LTCC substrate was presented and its thermo-mechanical reliability was analyzed in this paper, with emphasis on the reliability of heat reflow process, the operating state and fatigue of second-level solder joints. The configuration and assembly process of the SiP module were briefly introduced at first, and qualitative analysis was made according to the reliability problem that may occur in the manufacturing process and the operating state. Through FEM simulation, this paper studied the warpage and stress variation of the RF SiP module, as well as parametric studies of some key package dimensions. Solder joint reliability under temperature cycling condition was also analyzed in particular in this paper. The results show that for the heat reflow process and operating state, the maximum warpage is both on the top LTCC substrate, but the maximum stresses are on the outermost solder ball and the kovar column at the corner, respectively. There is a large residual stress on the critical solder ball at the end of the reflow process and the key package dimensions has little effect on it. The thickness of top LTCC substrate has a significant impact on the thermal deformation and thermal stress, followed by the height of kovar columns. The reason for the considerable thermal stress on the kovar column is the non-uniform of temperature distribution. The key to reducing thermal deformation and stress in the operating state is the employment of effective cooling measures. It is found by comparison that the reliability of critical solder joints can be greatly improved by adding suitable underfill.     

A compact LTCC-based Ku-band transmitter module

Presents design, implementation, and measurement of a three-dimensional (3-D)-deployed RF front-end system-on-package (SOP) in a standard multi-layer low temperature co-fired ceramic (LTCC) technology. A compact 14 GHz GaAs MESFET-based transmitter module integrated with an embedded bandpass filter was built on LTCC 951AT tapes. The up-converter MMIC integrated with a voltage controlled oscillator (VCO) exhibits a measured up-conversion gain of 15 dB and an IIP3 of 15 dBm, while the power amplifier (PA) MMIC shows a measured gain of 31 dB and a 1-dB compression output power of 26 dBm at 14 GHz. Both MMICs were integrated on a compact LTCC module where an embedded front-end band pass filter (BPF) with a measured insertion loss of 3 dB at 14.25 GHz was integrated. The transmitter module is compact in size (400 /spl times/ 310 /spl times/ 35.2 mil/sup 3/), however it demonstrated an overall up-conversion gain of 41 dB, and available data rate of 32 Mbps with adjacent channel power ratio (ACPR) of 42 dB. These results suggest the feasibility of building highly SOP integrated RF front ends for microwave and millimeter wave applications.     

LTCC 450 MHz CDMA功放模块的研制

对LTCC埋层电感进行了研究,以研制体积小、低损耗、微波性能好的高密度功放模块。利用商用三维电磁场分析软件HFSS对LTCC集成化功率放大器PA组装和互连中的关键参数进行了仿真和优化。研制出450MHzCDMA手机LTCC功率放大器,增益29.0dB,VSWR为2.0∶1,PAE为34%,体积为6mm×6mm×1.2mm。     

Thermal solutions for discrete and wafer-level RF MEMS switch packages

In discrete radio frequency (RF) microelectromechanical systems (MEMS) packages, MEMS devices were fabricated on silicon or gallium arsenide (GaAs) chips. The chips were then attached to substrates with die attach materials. In wafer-level MEMS packages, the switches were manufactured directly on substrates. For both types of packages, when the switches close, a contact resistance of approximately 1 /spl Omega/ exists at the contact area. As a result, during switch operations, a considerable amount of heat is generated in the minuscule contact area. The power density at the contact area could be up to 1000 times higher than that of typical power amplifiers. The high power density may overheat the contact area, therefore affect switch performance and jeopardize long-term switch reliabilities. In this paper, thermal analysis has been performed to study the heat dissipation at the switch contact area. The goal is to control the "hot spots" and lower the maximum junction temperature at the contact area. A variety of chip materials, including Silicon, GaAs have been evaluated for the discrete packages. For each chip material, the effect of die attach materials has been considered. For the wafer-level packages, various substrate materials, such as ceramic, glass, and low-temperature cofired ceramic (LTCC) have been studied. Thermal experiments have been conducted to measure the temperature at the contact area and its vicinity as a function of dc and RF powers. Several solutions in material selection and package configurations have been explored to enable the use of MEMS with chips or substrates with relatively poor thermal conductivity. For discrete MEMS packages, placing the die inside a copper cavity on the substrate provides significant heat dissipation. For wafer-level packages, thin diamond coatings on the substrate could reduce the hot-spot temperature considerably.     

A 1.9-GHz DECT CMOS power amplifier with fully integratedmultilayer LTCC passives

We present the first demonstration of a CMOS power amplifier (PA) utilizing fully integrated multilayer low-temperature co-fired ceramic (LTCC) high-Q passives for 1.9-GHz digital European cordless telecommunications (DECT) applications. The inductor and capacitor library were built in a multilayer LTCC board using a compact topology. An inductor Q-factor as high as 100 with a self-resonant frequency (SRF) as high as 8 GHz was demonstrated. Measured results of the CMOS-LTCC PA show good agreement with the simulated results exhibiting 48% power added efficiency, 26-dBm output power and 17-dB gain at 1.9 GHz with a 3.3-V drain supply voltage. This result is the first significant step toward a compact DECT transceiver module development utilizing fully integrated multilayer LTCC passives and a standard CMOS technology     

Embedded IC and high-Q passives technology for ultra-compact Ku-band VCO module

In this letter, we present a novel ultra-compact embedded IC integration approach for system-on-package (SOP) based solutions for RF and wireless communication applications. This concept is applied to the integration of a Ku band VCO module. The module fabrication is described and the impact of the packaging on the chip-set performances is discussed. The final thickness of the module is about 150 /spl mu/m. The embedded VCO exhibits an oscillation frequency of 15.4 GHz, a phase noise of -99.2 dBc/Hz at a 1 MHz offset and maximum output power of 10.67 dBm. Multilayer interconnects built with modified MCM-D technology using advanced photosensitive epoxy Intervia 8000 is described. Characterization and modeling of RF inductors are detailed and show quality factor as high as 80 at 10 GHz.     

The effect of RF-driven gate current on DC/RF performance in GaAs pHEMT MMIC power amplifiers

This paper describes RF-driven gate current effects on the dc/RF performance of 0.15-/spl mu/m (gate length) 2-mil (substrate thickness) GaAs pseudomorphic high-electron mobility transistor (pHEMT) monolithic microwave integrated circuit power amplifiers (PAs). High gate current is generated in PAs under RF drive at room temperature. A long-term lifetest of PAs with various gate currents induced by RF drive was performed to investigate the effect of RF-driven gate current on dc/RF performance in GaAs pHEMT PAs. Accordingly, an empirical model was developed to predict the dc/RF performance of V-band PA modules by the end of life (EOL). This information is crucial for system engineers in order to budget sufficient output power so that the system can still maintain performance capability by EOL.     

Application of simulation-based decision making in product development of an RF module

This paper presents results of simulation-based design evaluation for thermal and thermo-mechanical performance and cost of packaging technology of a RF module for automotive application. Combination of thermal, thermo-mechanical and cost analysis within the multi-attribute decision making enabled design ranking and revealed two MCM-L/D and MCM-D designs with wire bonding assembly preferred for use in automotive applications for different temperature environments. Simulation-based design guidelines were developed for designing electronic modules exhibiting good thermal and thermo-mechanical performance. By application-based partitioning of the importance weights assigned to the reliability and cost criteria, the guidelines were extended to cover other application areas.     

基于76.2 mm圆片工艺的GaN HEMT可靠性评估

报道了利用76.2 mm圆片工艺实现了SiC衬底GaN HEMT微波功率管的研制,并对其进行了多项试验以评估其可靠性.器件工艺中通过引入难熔金属作器件肖特基势垒,有效提高了GaN HEMT器件肖特基势垒的热稳定性,经过500℃高温处理30 s后器件肖特基特性依然保持稳定.随后的高温工作寿命试验表明,该GaNHEMT能够...     

Wavelength-tunable laser module using low-temperature cofired ceramic substrates

We realized a prototype series of the 1550-nm band wavelength-tunable laser module. The edge-emitting Fabry-Perot diode laser operates in the short external cavity configuration and is tuned by a silicon surface micromachined Fabry-Peacuterot interferometer device. Low-temperature cofired ceramic (LTCC) substrate technology was used in the module packaging to enable the passive alignment of the photonic components. Low conductor resistance and dielectric loss, multilayer structures with fine-line capability, compatibility with hermetic sealing, and the ability to integrate passive electrical components (resistors, capacitors, and inductors) into the substrate make LTCC a useful technology for telecommunication applications. In addition, the fair match of the thermal expansion coefficient to optoelectronic chips reduces packaging-induced thermomechanical stresses. The precision three-dimensional (3-D) structures, such as cavities, holes, and channels manufactured in the ceramic parts, ease the packaging process via the passive assembly. The wavelength tuning range of the realized modules ranged from 8 to 19 nm and single-mode fiber-coupled output power was between 100 and 570 muW. The hybrid arrangement uses standard laser chips and, therefore, potentially provides a cost-effective and easily configurable solution for last-mile fiber optic communications     

S波段高功率T/R组件的小型化和高可靠设计

介绍了一种S波段高功率T/R组件的小型化和高可靠设计技术。组件整体采用了一种＂三明治＂式电路结构形式,并使用多层微波复合介质基板完成高密度互连,使用集成双管功放单元和层压串馈功率合成器技术制作高功率密度功放电路。结果表明,用该技术方法研制的S波段高功率T/R组件输出功率可达800 W,重量约3 kg,长期工作稳定可靠。     

基于LTCC技术的多层垂直转换电路设计

低温共烧陶瓷(LTCC)是实现小型化、高可靠性多芯片组件的一种理想技术方式。多层转换电路实现了微波信号在基板内部传输。文章研究了微带线到带状线背靠背式多层转换电路,优化设计了通孔之间距离以及通孔到带状线之间的距离,仿真结果与实测较为吻合。     

X波段带幅度加权功能T/R组件设计

体积小、重量轻、高性能、高可靠性的T/R组件的研制已经成为目前的研究热点。介绍了一种具有收发幅度加权功能的X波段T/R组件的原理及设计方法,该组件基于多层低温共烧陶瓷(LTCC)工艺实现,在一块LTCC基板上集成了电阻、电容、ASIC、MMIC等器件,最后给出了组件的测试结果。主要性能:发射功率大于40 d Bm,接收增益大于20 d B,噪声系数小于3.5 d B,重量90 g。     

Process induced warpage in multitiled alumina substrates for largearea MCM-D processing

Electronics industries are responding to consumer demands in low-cost and high performance products for the 21st century, In order to find a low-cost solution for the future multichip module (MCM) packaging, a multitiling approach through the incorporation of several tiles on a large carrier substrate has been established in this study. The multitiling format provides simultaneous processing of several small (95-mm×135-mm) alumina tiles onto a carrier glass pallet with comparable coefficient of thermal expansion (CTE). The objective of this study is to develop materials and processes for a 300-mm×300-mm format that is scalable up to a 600 mm×600 mm substrate. The fabrication process begins with a carrier substrate on which tiles are attached using a low modulus adhesive. This composite structure is exposed to high temperature thin film process that is required for the MCM-deposited (MCM-D) processing. The tiles are detached from the carrier substrate at an elevated temperature (~4500°C). The warpage of these structures is a critical factor that determines the processability of the thin films in a manufacturing environment. This paper discusses the warpage issues associated with various stages of processing of the proposed large area MCM-D structures     

A direct Ku-band linear subharmonically pumped BPSK and I/Q vectormodulator in multilayer thin-film MCM-D

A direct Ku-band linear subharmonically pumped binary phase-shift keying (BPSK) and in-phase/quadrature (I/Q) vector modulator have been developed using multilayer thin-film multichip module (MCM-D) technology. All passives are integrated in the low cost MCM-D substrate. To the authors knowledge, this is the first modulator based on thin-film integrated passive components. The subharmonic mixing is performed using a beam-lead antiparallel diode pair mounted onto the MCM using thermocompression. A custom diode model has been developed and verified using nonlinear network analyzer measurements: an excellent agreement between the measured and simulated powers and phases for more than nine harmonics is demonstrated. Additionally, it is shown that an optimal reactive termination for the third harmonic of the local oscillator (LO) exists such that a very flat BPSK mixer conversion is obtained. This is validated by measurements that indicate a ±0.25-dB variation on the conversion loss for an LO frequency varying from 6.8 to 7.6 GHz. The I/Q vector modulator consists of a Wilkinson power divider, a coplanar-waveguide Lange coupler, and two BPSK modulators. It has a measured image rejection better than -27 dB over the RF range of 13.4-15.2-GHz band (corresponding to a vector phase and amplitude error lower than 2° and 1%). The image rejection is even better than -32 dB over the very small aperture terminal band (RF: 14-14.5 GHz)     

Efficiency improvement of a DC/DC converter using LTCC substrate

We propose a substrate with high thermal conductivity, manufactured by the low‐temperature co‐fired ceramic (LTCC) multilayer circuit process technology, as a new DC/DC converter platform for power electronics applications. We compare the reliability and power conversion efficiency of a converter using the LTCC substrate with the one using a conventional printed circuit board (PCB) substrate, to demonstrate the superior characteristics of the LTCC substrates. The power conversion efficiencies of the LTCC‐ and PCB‐based synchronous buck converters are 95.5% and 94.5%, respectively, while those of nonsynchronous buck converters are 92.5% and 91.3%, respectively, at an output power of 100 W. To verify the reliability of the LTCC‐based converter, two types of tests were conducted. Storage temperature tests were conducted at ?20 °C and 85 °C for 100 h each. The variation in efficiency after the tests was less than 0.3%. A working temperature test was conducted for 60 min, and the temperature of the converter was saturated at 58.2 °C without a decrease in efficiency. These results demonstrate the applicability of LTCC as a substrate for power conversion systems.     

LTCC-Based Highly Integrated Millimeter-Wave Receiver Front-End Module

This paper presents the design and fabrication of a highly integrated Low Temperature Co-fired Ceramic (LTCC) receiver front-end module. This LTCC module is a dual channel receiver module, works at Ka-band, and fabricated including six Ferro A6M dielectric layers and five metal layers, contains eight embedded resistors and eight MMICs. All MMICs are mounted into pre-making cavities on the top surface of the LTCC substrate. Three slot coupled waveguide-to-microstrip transitions are integrated at LTCC substrate to realize RF and LO signal input. The developed module is highly integrated and reliable, which has a compact size of 58 × 50 × 22 mm³ (including the metal cavity). Each channel of the receiver has the noise figure of less than 9 dB and the gain of more than 24 dB at Ka-band.     

UHF宽带大功率放大器模块

报道了自行设计并研制成功的UHF宽带大功率放大器模块,该模块在1.35～1.85 GHz频带内增益高于44 dB,输出功率大于10 W,增益平坦度≤± 0.7 dB.同时对射频功率放大器的稳定性进行了分析与讨论,提出了提高射频功率放大器稳定性的方法,即要设法排除带外不稳定因素以及设计合理的偏置网络,这对射频功率放大器的稳定性有明显的改善.     

MCM-D技术电热特性综述

本文主要说明了淀积型多芯片组件(MCM-D)技术所使用的主要材料的热特性。此技术采用倒装片技术把硅芯片安装到硅基板上。阐述了薄膜电阻和接触电阻的测量与所使用金属的温度范围-28℃-100℃的比较。一套典型的试验结构诸如开尔文接触、横桥电阻(CBR)及Van der Pauw 结构不仅已用于此技术,而且为了测试通过球倒装片连接的接触电阻,采用一新的开尔文式结构。已获得MCM封装的热模型,并考虑由此类封装增加的所有的热电阻。