Printed microinductors on flexible substrates for power applications

A low-profile microinductor was fabricated on a copper-clad polyimide substrate where the current carrying coils were patterned from the existing metallization layer and the magnetic core was printed using a magnetic ceramic-polymer composite material. Highly loaded ferrite-polymer composite materials were formulated, yielding adherent films with 4/spl pi/M/sub s//spl ap/3900 G at +5000 Oe applied DC field. These composite magnetic films combine many of the superior properties of high temperature ceramic magnetic materials with the inherent processibility of polymer thick films. Processing temperatures for the printed films were between 100/spl deg/C and 130/spl deg/C, facilitating integration with a wide range of substrates and components. The quality factor of the microinductor was found to peak at Q=18.5 near 10 MHz, within the optimal frequency range for power applications. A flat, nearly frequency independent inductance of 1.33 /spl mu/H was measured throughout this frequency range for a 5 mm/spl times/5 mm component, with a DC resistance of 2.6 /spl Omega/ and a resonant frequency of 124 MHz. The combination of printed ceramic composites with organic/polymer substrates enables new methods for embedding passive components and ultimately the integration of high Q inductors with standard integrated circuits for low profile power electronics.     

A fully-integrated low-power low-noise 2.6-GHz bipolar VCO forwireless applications

The low quality factor of the inductors fabricated in fully-integrated LC tanks results in a poor indirect stability of the oscillators, which are therefore highly sensitive to low-frequency noise and disturbances coupled through substrate and supply lines. The paper addresses the design of a 2-V voltage-controlled oscillator (VCO) at 2.6 GHz fabricated in a Si-bipolar process with f_T of 20 GHz. The circuit bias and the transistor layout have been specifically optimized to minimize the phase noise degradation due to the intrinsic low indirect stability. A single sideband-to-carrier ratio (SSCR) of -104 dBc/Hz at 100 kHz is demonstrated with less than 14 mW power consumption     

A universal dual band LNA implementation in SiGe technology forwireless applications

A dual band low-noise amplifier (LNA) with matched inputs and outputs, implemented in Infineon Technologies' B7HF SiGe process, is presented. Both the single-ended inputs and outputs are matched to 50 Ω without external elements. For the low-band (800 MHz-1 GHz), the LNA has a measured gain of 17 dB and a noise figure below 1.2 dB at 900 MHz. The high-band (1.8-2 GHz) LNA achieves a gain of 15 dB and a noise figure below 1.5 dB at 1.9 GHz. Both LNAs consume 5 mA dc current with a power supply voltage range from 2.7-3.6 V     

A low-noise, low-power VCO with automatic amplitude control forwireless applications

Voltage controlled oscillators (VCOs) used in portable wireless communications applications, such as cellular telephony, are required to achieve low phase-noise levels while consuming minimal power. This paper presents the design challenges of a VCO with automatic amplitude control, which operates in the 300 MHz to 1.2 GHz frequency range using different external resonators. The VCO phase noise level is -106 dBc/Hz at 100-KHz offset from an 800-MHz carrier, and it consumes 1.6 mA from a 2.7-V power supply. An extensive phase-noise analysis is employed for this VCO design in order to identify the most important noise sources in the circuit and to find the optimum tradeoff between noise performance and power consumption     

A 2.2-V operation, 2.4-GHz single-chip GaAs MMIC transceiver forwireless applications

A 2.2-V operation, single-chip GaAs MMIC transceiver has been successfully developed for 2.4-GHz-band wireless applications such as wireless local area network terminals. The chip is fabricated using a planar self-aligned gate field-effect transistor. To generate sufficient negative voltage for gate-biasing and to enhance switch power handling capability under a 2.2-V supply, a newly designed negative voltage generator with a voltage doubler (NVG-VD) and a switch control logic circuit are integrated on the chip, together with a power amplifier, a transmit/receive switch, and a low-noise amplifier. The NVG-VD is designed to produce both a 3.3-V positive step-up voltage and a -2.1-V negative voltage under 2.2 V in operation voltage. Biased with these outputs, the logic circuit accommodates high power outputs of over 25 dBm with a low operating voltage of 2.2 V in transmit mode, With a 2.45-GHz modulated signal based on IS-95 standards, a 21-dBm output power and a 33% efficiency are obtained at a ±1.25-MHz-offset adjacent channel power rejection of -45 dBc. In receive mode, a low-noise amplifier achieves a 1.8-dB noise figure and an 11-dB gain with a 3.0-mA current. This transceiver enables significant size and weight reductions in 2.4-GHz-band wireless application terminals     

A comparative evaluation of DECT, PACS, and PHS standards forwireless local loop applications

In a comparative analysis the performance and capacity of DECT, PACS, and PHS for wireless local loop applications have been investigated. This article reports the results of both qualitative and quantitative analyses. The qualitative evaluation consists of a detailed comparison of the parameters of each standard and their relevance in WLL applications. In the quantitative analysis detailed simulations were performed covering diverse sets of conditions. The results of both types of analysis are presented. A major conclusion is that all three standards provide satisfactory performance for WLL applications. For low traffic environments PACS, which can employ larger cells, performs better than the other two standards. In suburban areas where, in addition to coverage capabilities, capacity is an issue, DECT has better performance. For high traffic density urban areas with great capacity requirements, the three standards all have good performance     

Low voltage, high efficiency GaAs Class E power amplifiers forwireless transmitters

A Class E power amplifier for mobile communications is presented. The advantages of Class E over Class B, Class C, and Class F power amplifiers in a low voltage design are discussed. A fully integrated Class E power amplifier module operating at 835 MHz is designed, fabricated, and tested. The circuit is implemented in a self-aligned-gate, depletion mode 0.8-μm GaAs MESFET process. The amplifier delivers 24 dBm of power to the 50-Ω load with a power added efficiency greater than 50% at a supply voltage of 2.5 V. The power dissipated in the integrated matching networks is 1.5 times the power dissipated in the transistor     

The partial silicon-on-insulator technology for RF power LDMOSFET devices and on-chip microinductors

A new partial silicon-on-insulator (SOI) formation technology and the associated RF LDMOSFET device structure on a silicon bulk substrate are proposed in this paper. The same technology can also be applied to enhance the quality factor of the integrated on-chip microinductors. The proposed technology is able to reduce both drain/substrate parasitics and leakage current for devices fabricated on bulk substrates. At the same time, the approach overcomes the thermal problem encountered by devices fabricated on full-SOI substrates. To demonstrate the technology, both partial-SOI LDMOSFET and microinductor devices were fabricated on a bulk wafer with their RF performance verified by laboratory measurements.     

Joint optimal channel base station and power assignment forwireless access

The provision of personal communication services is the goal of the evolution of integrated communication systems. The fundamental problem underlying any phase (hand-off, new connection, etc.) of a dynamic resource allocation algorithm in a wireless network is to assign transmission powers, forward (downstream) and reverse (upstream) channels, and base stations such that every mobile of the system can establish a connection. Each one of these problems separately has been studied extensively. We consider the joint problem in a system with two base stations. An algorithm that achieves the optimal assignment is provided. It involves the computation of a maximum matching in a graph that captures the topological characteristics of the mobile locations. The traffic capacities, in terms of expected number of connections per channel, of the forward and reverse channel are obtained and compared, for both cases of power control and nonpower control. It turns out that when the transmission power is fixed, the capacities of the forward and reverse channel are different, while when power control is allowed they are the same. For systems with two mobiles the capacities of the forward and reverse channels are studied analytically. Finally, several versions of the two-way channel assignment problem are studied     

射频高Q值MLCC的设计和工艺

为了提高射频多层陶瓷电容器( MLCC)的Q值,采用NPO瓷粉、钯银内电极浆料和银端电极浆料等为原材料制备MLCC.研究了设计和工艺对所制MLCC的固有寄生参数Rs和Ls的影响.结果表明:特殊的设计能减小内电极电阻和内外电极的接触电阻;合适的内电极厚度保证了烧结后内电极良好的连续性;合理的倒角和烧端工艺保证了内外电极的...     

A high performances CMOS CCII and high frequency applications

In this paper, we propose an improved translinear based CCII configuration. Heuristic algorithm is used for optimal sizing regarding static and dynamic performances. PSPICE simulations for AMS 0.35 μm CMOS technology show that the current and voltage bandwidths are respectively 2.6 GHz and 3.9 GHz, and the parasitic resistance at port X (R _X ) has a value of 18 Ω for a control current of 100 μA. The improved configuration is used as a building block into high frequency design applications: a current controlled oscillator and a tunable fully integrable band pass filter. The oscillator frequency can be tuned in the range of [290–475 MHz] by a simple variation of a DC current. The central frequency of the band pass filter can be varied in the range of [1.22–1.56 GHz] and the quality factor vary in the range [8–306] with a simple variation of a DC current.     

Ultra-low-power and high-speed SiGe base bipolar transistors forwireless telecommunication systems

Ultra-low-power and high-speed SiGe base bipolar transistors that can be used in RF sections of multi-GHz telecommunication systems have been developed. The SiGe base and a poly-Si/SiGe base-contact were formed by selective growth in a self-aligned manner. The transistors have a very small base-collector capacitance (below 1 fF for an emitter area of 0.2×0.7 μm) and exhibit a high maximum oscillation frequency (30-70 GHz) at low current (5-100 μA). The power-delay product of an ECL ring oscillator is only 5.1 fJ/gate for a 250-mV voltage swing. The maximum toggle frequency of a one-eighth static divider is 4.7 GHz at a switching current of 68 μA/FF     

Q band interferometer for high temperature measurements

A Q band interferometer for determining the complex permittivity of solids and liquids between 20°C and 1300°C has been developed. The Roberts and Von Hippel standing-wave method was used. The technique involves the utilization of a computer-assisted digital voltmeter for data acquisition and treatment. Results for a 67SiO₂?33Na₂O within the temperature range 20–400°C and in the liqid state (950°C) are presented.     

基于CRC法的无线通信系统在线误码率监测研究

针对传统误码监测方法未对通信节点分布情况进行分析,出现误码监测结果不佳及监测耗时长等问题,提出无线通信系统在线误码自动化监测方法。在相关工作分析的基础上,通过对通信系统进行前处理,结合处理所得通信数据,并将通信数据簇的发生情况近似看作一个泊松过程,构建复合型泊松模型,得出误码分布结果。以此为依据,引入CRC方法计算丢失码与反转码数量,求解得出通信系统误码率,完成无线通信系统在线误码自动监测。实验结果表明,所提方法的通信数据采集质量较高,误码监测结果与实际情况基本一致,且监测耗时最长不超过10 s,性能优越,为无线通信相关领域的发展提供了参考依据。     

Polarizing grating coupler for high Q laser cavities

A coupling grating made in the last high-index layer of a highly reflective multilayer laser output mirror, located at the outside of the laser cavity, induces a significant fall of the reflection coefficient for one of the polarizations. The lasing polarization does not suffer more than 0.1% scattering. The understanding of device operation revealed by experiments shows the way for achieving an industrial manufacturing scheme, despite the poor control which layer-deposition technologies presently have on the layer index and thickness separately.     

针对高频宽带应用的SiGeHBT

以移动电话和无线局城网(WLAN)为首的无线应用产品,正在急速向高频宽带发展。尤其是在WLAN数字无绳电话等领域,以往一直是2GHz带宽,现在也开始利用5GHz(请参阅图1)。在WLAN的核心部件高频放大器里,一直都是使用GaAs器件,但是GaAs器件价格昂贵．人们期待在成本方面更为有利的高性能SiGe器件早日上市。     

A quantitative comparison of multiple access control protocols forwireless ATM

The multiple access control (MAC) problem in a wireless network has intrigued researchers for years. For a broad-band wireless network such as wireless ATM, an effective MAC protocol is very much desired because efficient allocation of channel bandwidth is imperative in accommodating a large user population with satisfactory quality of service. Indeed, MAC protocols for a wireless ATM network in which user traffic requirements are highly heterogeneous (classified into CBR, VBR, and ABR), are even more intricate to design. Considerable research efforts expended in tackling the problem have resulted in a myriad of MAC protocols. While each protocol is individually shown to be effective by the respective designers, it is unclear how time different protocols compare against each other on a unified basis. In this paper, we quantitatively compare seven previously proposed TDMA-based MAC protocols for integrated wireless data and voice services. We first propose a taxonomy of TDMA-based protocols, from which we carefully select seven protocols, namely SCAMA, DTDMA/VR, DTDMA/PR, DQRUMA, DPRMMA, DSA++, and PRMA/DA, such that they are devised based on rather orthogonal design philosophies. The objective of our comparison is to highlight the merits and demerits of different protocol designs     

High Q inductors for wireless applications in a complementarysilicon bipolar process

Rectangular spiral inductors with Q's over 12 have been built in a high-speed complementary bipolar process and characterized for use in wireless applications. An accurate broadband model for the inductors has been developed, and a test filter and mixer have been built to verify the performance of the inductors and the accuracy of the model     

Adaptive allocation of resources and call admission control forwireless ATM using genetic algorithms

In wireless ATM-based networks, admission control is required to reserve resources in advance for calls requiring guaranteed services. In the case of a multimedia call, each of its substreams (i.e., video, audio, and data) has its own distinct quality of service (QoS) requirements (e.g., cell loss rate, delay, jitter, etc.). The network attempts to deliver the required QoS by allocating an appropriate amount of resources (e.g., bandwidth, buffers). The negotiated QoS requirements constitute a certain QoS level that remains fixed during the call (static allocation approach). Accordingly, the corresponding allocated resources also remain unchanged. We present and analyze an adaptive allocation of resources algorithm based on genetic algorithms. In contrast to the static approach, each substream declares a preset range of acceptable QoS levels (e.g., high, medium, low) instead of just a single one. As the availability of resources in the wireless network varies, the algorithm selects the best possible QoS level that each substream can obtain. In case of congestion, the algorithm attempts to free up some resources by degrading the QoS levels of the existing calls to lesser ones. This is done, however, under the constraint of achieving maximum utilization of the resources while simultaneously distributing them fairly among the calls. The degradation is limited to a minimum value predefined in a user-defined profile (UDP). Genetic algorithms have been used to solve the optimization problem. From the user perspective, the perception of the QoS degradation is very graceful and happens only during overload periods. The network services, on the other hand, are greatly enhanced due to the fact that the call blocking probability is significantly decreased. Simulation results demonstrate that the proposed algorithm performs well in terms of increasing the number of admitted calls while utilizing the available bandwidth fairly and effectively