Radiation properties of parabolic torus reflector

General radiation-pattern formulas for a torus reflector antenna have been developed using physical optics. These expressions are valid at arbitrary feed locations not only within the primary focal arc but also for beam scanning with squinted feed horn illuminations. Numerical results were obtained at 22 GHz for an experimental 1.25 m×2.5 m torus reflector in both elevational beam scanning and extended azimuthal scanning outside the primary ±15° field of view. An elevation scanning range of 7° showed only a 1 dB gain reduction. The 20° azimuth beam (i.e. 5° extended azimuth scanning) showed a 1.4 dB gain reduction. Comparison between calculated and measured patterns showed agreement in beamwidth and most pattern features. The discrepancy between calculated and measured sidelobe levels in the azimuthal plane is attributed to imperfection enhancement by the horizontal oversize of the reflector     

附加相位修正副面的多波束环面天线方向图

首先利用等光程条件导出了抛物环面上的点与副面上的点的关系公式；其次，巧妙地利用微波光学强度定律、几何光学法和物理光学法给出了计算“附加相位校正副面的多波束抛物环面天线”的辐射方向图公式；最后，利用所得的辐射方向图公式对一个实际天线进行了理论计算，理论计算值和实验测试值吻合异常良好。     

Log domain filtering for RF applications

A new second-order log filter topology, which is particularly useful for RF signal processing, is introduced with a discussion of how its features meet the needs of RF design. The design concept behind log filters is reviewed. Simulation and experimental results on a test IC are presented for an electronically tunable filter which operates beyond 400 MHz, with Q's in excess of 60, using the AT&T CBIC-V2 process     

Integrated CMOS wideband oscillator for RF applications

A fully integrated LC oscillator with a tuning range of 800 MHz is presented. A combination of capacitive and inductive tuning has been used to produce the large tuning range with a low-gain control input. The phase noise at 1.9 GHz is as low as -120 dBc/Hz at 500 kHz offset. Possible applications include integer-N PLLs with a low level of reference spurs     

CMOS RF circuits for data communications applications

The author describes the recent development of two analog CMOS circuits operating at RF frequencies with applications to data communications. One is a four-quadrant analog multiplier which exhibits a 100-MHz bandwidth with a measured linearity error of 0.7% for X and Y inputs of 0.6 and 0.8 V, respectively. The other is a 90/spl deg/ phase shifter which maintains the grain and phase errors of less than 0.5 dB and 3/spl deg/, respectively, for a signal within 40-60-MHz frequency range.     

CMOS four-quadrant analogue multiplier for RF applications

A CMOS four-quadrant multiplier consisting of four MOS transistors operating in the saturation region is introduced. The circuit exploits the quadratic relation between the current and voltage of the MOS transistor in saturation. Simulation results show that, for a supply voltage of 1.2 V multiplication can be performed at a frequency of 1.8 GHz, achieving better performances than a recently proposed similar architecture     

Indium antimonide based HEMT for RF applications

We report on an indium antimonide high electron mobility transistor with record cut-off frequency characteristics.For high frequency response it is important to minimize parasitic resistance and capacitance to improve short-channel effects.For analog applications adequate pinch-off behavior is demonstrated.For proper device scaling we need high electron mobility and high electron density.Toward this end,the device design features and simulation are carried out by the Synopsys TCAD tool.A 30 nm In Sb HEMT exhibits an excellent cut-off frequency of 586 GHz.To the knowledge of the authors,the obtained cut-off frequency is the highest ever reported in any FET on any material system.     

SiGe BiCMOS technology for RF circuit applications

SiGe BiCMOS is reviewed with focus on today's production 0.18-/spl mu/m technology at f/sub T//f/sub MAX/ of 150/200 GHz and future technology where device scaling is bringing about higher f/sub T//f/sub MAX/, as well as lower power consumption, noise figure, and improved large-signal performance at higher levels of integration. High levels of radio frequency (RF) integration are enabled by the availability of a number of active and passive modules described in this paper including high voltage and high-power devices, complementary PNPs, high quality MIM capacitors, and inductors. Key RF circuit results highlighting the advantages of SiGe BiCMOS in addressing today's RF IC market are also discussed both for applications at modest frequencies (1 to 10 GHz) as well as for emerging applications at higher frequencies (20 to >100 GHz).     

无线局域网射频前端器件的选择--化系统性能和电流消耗

一个802．11WLAN无线电接收装置的前端一般由滤波器、开关、功率放大器(PA)、平衡一不平衡转换器、分立器件组成,有时还包括低噪声放大器(LNA)。应细心选择这些器件和他们的结构,以满足、优化在性能、法规、电流消耗和成本方面的要求。     

Design,modeling and characterization of a joint for inflatable robotic arms

This paper investigates the design and modeling of a joint for inflatable robotic arms (IRAs) towards long-range inspection. A primary trade-off design is elaborated in view of materials, fabrication and actuation through the detailed comparison of some existing IRAs. Antagonist pneumatic artificial muscles (PAMs) are selected to actuate each joint that is fabricated from low-cost fabrics or films. A novel static joint model is proposed by taking into account both the stiffness of irregular-shaped inflatable tubes and the nonlinear issue of PAMs, without the need for numerous experiments or computationally expensive algorithms. The proposed modeling approach, which aims to predict joint behaviors analytically, is experimentally validated on two different prototypes. Particularly, the integration of the beam and membrane models is introduced, so that the stiffness model achieves the most accurate prediction with a mean absolute percentage error (MAPE) of 21.60 % as compared to its separate counterparts. Following this, the model-based optimization of the IRA joint is carried out for a further trade-off among its motion range, payload capacity and weight. Experiments on the optimized prototype are conducted to characterize its bending modality and force output, showing the great potential of our method for some specific applications, e.g., disaster inspection, space exploration and domestic assistance.     

A three-terminal SOI gated varactor for RF applications

This paper presents a new CMOS compatible SOI gated varactor for use in RF ICs. With its additional third terminal, the device offers an exceptional large tuning range and a good quality factor. The result of the MEDICI simulation of the structure of the varactor has been confirmed with measured data. A VCO circuit that can potentially exploit the three-terminal property is also reported     

Advanced CMOS technology portfolio for RF IC applications

A high quality 90-nm CMOS-based technology portfolio suitable for various RF IC applications is presented. The portfolio is built up by a wide selection of active and passive components and a user-friendly process design kit (PDK). Layout-optimized RF components are studied in details including state-of-the-art 90 nm RFMOS devices with 120-160 GHz f/sub T/ and very low noise figures, varactors with tradeoff between quality factor and tuning ratio, precision capacitors with metal-insulator-metal and metal-over-metal schemes, and a variety of inductor structures suitable for different RF designs. The effectiveness for isolating substrate RF noise is also compared among several layout schemes. Finally the guidelines and requirements for constructing a useful PDK are addressed.     

MIM capacitor integration for mixed-signal/RF applications

The relentless drive toward high-speed and high-density silicon-based integrated circuits (ICs) has necessitated significant advances in processing technology. The entrance of copper metallization in IC manufacturing has resulted in new challenges in metal-insulator-metal (MIM) capacitor fabrication, one of the key building blocks in analog/mixed signal/RFCMOS circuits. The requirement to reduce passive chip space has led to active researches for MIM with high dielectric constant (/spl kappa/) film. This paper provides an overview of MIM capacitor integration issues with the transition from AlCu backend of line (BEOL) to Cu BEOL. The key to MIM capacitor electrical properties can be achieved with optimized dielectrics. The different MIM capacitor architectures published are also described. Special emphasis is made on the properties of various MIM with high-/spl kappa/ dielectrics in the last section.     

RF CMOS on high-resistivity substrates for system-on-chip applications

The use of a high-resistivity substrate extends the capability of standard digital CMOS technology to enable the integration of high-performance RF passive components. The impact of substrate resistivity on the key components of RF CMOS for system-on-chip (SoC) applications is discussed. The comparison includes the transistor, transmission line, inductor, capacitor and varactor, as well as the noise isolation. We also discuss the integration issues including latch-up and well-well isolation in a 0.35-/spl mu/m Cu metal pitch, 0.1-/spl mu/m-gate-length RF CMOS technology.     

Integrated interconnect networks for RF switch matrix applications

In this paper, two new types of integrated RF interconnect networks are presented. The circuits are printed on double-sided alumina substrates, eliminating the need to use multilayer manufacturing technology. The interconnect networks employ finite ground coplanar lines and vertical transitions and can be easily integrated with semiconductor and microelectromechanical-systems switches. A wide-band 3/spl times/3 interconnect network utilizing single and double three-via vertical transitions is investigated theoretically and experimentally. The measured results show a return loss of -20dB and an isolation of better than -40dB up to 30 GHz. A vialess double-sided interconnect network is also studied and optimized for satellite Ku-band applications. This type of interconnect network uses a process requiring only front and back pattern metallization. The measured results indicate a return loss of better than -17dB and an isolation of better than -45dB.     

Superjunction LDMOS on thick-SOI technology for RF applications

The feasibility of applying the superjunction (SJ) concept to a thick-SOI LDMOS transistor for RF base station applications is studied in this paper. The electrical performances of SJ thick-SOI LDMOS transistors are compared with those of the conventional RF LDMOS counterparts through an extensive 3D simulation work in terms of transconductance (g_m), specific-on resistance (R_ON), voltage capability (V_BR) and C-V characteristics. It is expected that SJ thick-SOI LDMOS structures will exhibit a significant R_ON reduction thanks to the N-doping concentration increment in the drift region. The charge balance in structures integrated on thick-SOI substrates with a P-type epitaxial layer requires a fit of the N and P pillar doping concentration, being the P pillar slightly lower doped than the N one. Variation of pillars doping concentrations is directly related to the device performance. Therefore, the R_ON/V_BR trade-off and the R_ON components and the C_gd evolution are shown as a function of pillar doping ratio.     

A new trench bipolar transistor for RF applications

A new vertical trench SiGe heterojunction bipolar transistor (HBT) is proposed that improves the tradeoff between the cutoff frequency (f/sub T/) and the off-state collector-base breakdown voltage (BV/sub cbo/). Extensive device simulations show that a record f/sub T//spl middot/BV/sub cbo/ product of about 2375 GHz/spl middot/V can be obtained for an HBT having a trench field plate connected to the emitter and a linearly graded doping profile in the collector drift region, while about 700 GHz/spl middot/V can be obtained for a standard optimized HBT. This large improvement is explained mainly by the suppression of the base-widening effect.     

Large signal RF power transmission characterization of InGaP HBT for RF power amplifiers

The large signal RF power transmission characteristics of an advanced InGaP HBT in an RF power amplifier are investigated and analyzed experimentally. The realistic RF powers reflected by the transistor, transmitted from the transistor and reflected by the load are investigated at small signal and large signal levels. The RF power multiple frequency components at the input and output ports are investigated at small signal and large signal levels, including their effects on RF power gain compression and nonlinearity. The results show that the RF power reflections are different between the output and input ports. At the input port the reflected power is not always proportional to input power level; at large power levels the reflected power becomes more serious than that at small signal levels, and there is a knee point at large power levels. The results also show the effects of the power multiple frequency components on RF amplification.     

InGaP HBT 大信号RF功率传输特性

本文实验研究了用于RF功率放大器的先进的InGaP HBT 器件大信号RF功率传输特性。研究了InGaP HBT在小信号和大信号状态下输出端的发射功率和反射功率及输入端的反射功率的规律。分析了InGaP HBT RF功率信号的多频率功率成份及其对大信号功率增益压缩,非线性和RF输出功率饱和的影响。     

A dual-band RF front-end for WCDMA and GSM applications

An RF front-end for dual-band dual-mode operation is presented. The front-end consumes 22.5 mW from a 1.8-V supply and is designed to be used in a direct-conversion WCDMA and GSM receiver. The front-end has been fabricated in a 0.35-μm BiCMOS process and, in both modes, can use the same devices in the signal path except the LNA input transistors. The front-end has a 27-dB gain control range, which is divided between the LNA and quadrature mixers. The measured double-sideband noise figure and voltage gain are 2.3 dB, 39.5 dB, for the GSM and 4.3 dB, 33 dB for the WCDMA, respectively. The linearity parameters IIP3 and IIP2 are -19 dBm, +35 dBm for the GSM and -14.5 dBm and +34 dBm for the WCDMA, respectively