Ka 波段功率放大器线性化技术的研究

功率放大器是毫米波发射系统的关键部件,近年来对其线性度的要求越来越高,但关于Ka 波段的线性化研究却相对滞后。本文介绍了一种毫米波频段的线性化方案,采用预失真技术在中频模块产生预失真信号,然后上变频到Ka 频段,最终实现毫米波功率放大器的线性工作。通过仿真,三阶分量改善了10dB,达到了预期效果。     

新型无本振毫米波光纤无线通信上变频系统

基于低速信号注入法-珀(FP)激光器可实现无微波本振光纤无线通信(RoF)上变频技术,但是得到的微波本振频率受到FP激光器中四波混频效率的限制,难以直接实现毫米波载波的RoF上变频。在注入锁定FP激光器的基础上提出了一种新型的、低成本的在光域直接产生毫米波载波的RoF上变频方案。由于注入锁定FP激光器过程中的动态载流子特性,上变频得到的载波信号带有正啁啾,故可用负色散介质对载波信号进行脉冲压缩,从而增强高阶谐波分量以完成毫米波载波的无本振RoF上变频。实验中采用2 Gb/s非归零码注入实现了载波为13.9 GHz,用2.5 Gb/s注入实现了载波分别为13.9 GHz和15.4 GHz的RoF上变频,并采用上述方案分别实现27.8 GHz和30.8 GHz的倍频载波分量的增强。进一步实验验证了用本方案实现载波频率约60 GHz可调谐毫米波的无本振RoF上变频的可行性。     

基于微带无源电路的宽带毫米波分谐波混频器（英文）

设计了一款基于微带结构的宽带毫米波分谐波混频器。混频器中引入了短路结构的宽带射频滤波器以及一个高性能本振-中频双工器,这些无源电路能够抑制空闲组合频率,同时为中频、射频以及本振信号提供合适的回路。测试结果表明,本文设计的毫米波分谐波混频器射频工作频率为27～48 GHz,中频工作频率宽至6 GHz.在整个工作频段内上、下变频损耗均小于12.5 dB。当射频为33 GHz,中频为1 GHz时,上变频、下变频达到最小变频损耗分别为8.2 dB和7.5 dB。     

受激布里渊散射在被动毫米波综合孔径成像中的运用

提出了一种将受激布里渊散射(SBS)应用于被动毫 米波综合孔径成像中的方案。运用光纤SBS效应,对毫米波的 抑制载波双边带(DSB-SC)调制信号的一个边带进行放大同时抑制另一个边带,实现毫米波 信号的抑制载波单边带(SSB-SC)调制。将该方案应用 于被动毫米波综合孔径成像中,在获得毫米波信号上变频的同时实现了光学滤波以及单边 带功率放大。深入分析了SBS实现SSB-SC调制的原理以及运用于被动毫米波综 合孔径成像中的可行性。实验结果表明:本文方案可以有效 实现毫米波的上变频、功率放大及滤波功能;与传统电光调制系统相比,本文方案简单有效 ,由于系统对携带毫米波信息的边带有放大作用,可以运用于毫米波功率较低时的成像。     

基于FPGA+DSP的数字中频收发机的设计

基于数字下/上变频的原理,以FPGA+DSP为核心提出了一种高性能数字中频收发机的实现方案。首先阐述了直接数字下变频和数字上变频的实现原理,提出了延时校正滤波器的设计方法和滤波系数。之后探讨了模数转换器采样电路、数字下/上变频的FPGA设计逻辑、DSP数据读写和处理流程、数模转换器转换及滤波电路的实现方法。最后对实际系统进行了回环测试,测试结果表明该系统具有良好的实时性。     

《电讯技术》专题资料《雷达探测技术》题要（五）

毫米波有源相控阵TR组件研究（黄建,甘体国） 毫米波TR组件毫米波是毫米波有源相控阵的关键部件,其高精度数字移相、集成化和小型化对目前毫米波技术提出了很高要求。本文介绍了一种采用中频移相的新颖毫米波有源相控阵TR组件及其研究工作。     

一种基于FPGA的直接数字射频上变频方案

传统模拟器件实现射频(RF)上变频方法存在硬件复杂度高,灵活性差,功耗大等缺点。随着半导体器件的发展,软件无线电要求将上变频中射频或中频的信号处理尽量往基带数字信号处理靠拢。本文利用多相滤波器原理,提出一种基于现场可编程门阵列(FPGA)的直接数字RF上变频架构和实施方案,并且通过软硬件仿真验证了该方案的可行性。     

一种通用数字中频正交扩频调制器的实现

提出了一种适应于宽带扩频通信系统的数字中频调制的实现方案,它基于正交调制、DDS、数字上变频和数字内插等技术,采用通用硬件平台,可以生成多种中频调制信号,可广泛用于数字化扩频通信电台、宽带CDMA、软件无线电、遥控遥测等通信系统中。     

中频数字信号处理的DSP实现

介绍了软件无线电中频数字信号的处理方法及原理,并着重介绍了采用数字信号处理器(DSP)直接对中频数字信号进行数字下变频、基带和数字上变频的处理,从而使中频数字信号的处理更加灵活和方便。     

ROF系统中基于SOA非线性效应的光子上变频技术研究

在光载射频（ROF）系统中,为了将承载信息的光基带信号上变频到微波／毫米波波段,本文基于半导体光放大器（SOA）中的交叉增益调制（xGM）和交叉相位调制（XPM）效应实现了光子上变频：即实现了1．25Gb／s基带信号到30GHz的毫米波信号的转换。文中分析了SOA驱动电流的变化（50～200mA）和信号光与本振光波长间...     

A 31-GHz monolithic GaAs mixer/preamplifier circuit for receiver applications

The portion of a monolithic receiver containing integrated Schottky mixer diodes and MESFET'S with microstrip circuitry has been developed and tested at 31 GHz. This work is part of a program to establish the feasibility of monolithic receivers and transmitters at microwave and millimeter-wave frequencies. Receiver designs using high-cutoff frequency diodes in a mixer configuration followed by a MESFET amplifier are capable of operating from microwave through millimeter-wave frequencies. However, the fabrication of monolithic receiver designs requires the integration on the same wafer of devices with different material requirements. We have developed a compatible integration scheme which is fundamental to the fabrication of monolithic receivers at millimeter-wave frequencies. Fabrication and design considerations for the 31-GHz balanced mixer and IF preamplifier are described. Completed monolithic units typically exhibit a conversion gain of 4 dB from the signal frequency of 31 GHz to the IF frequency of 2 GHz. The associated noise figure is typically 11.5 dB.     

Design and measurements of a novel subharmonically pumpedmillimeter-wave mixer using two single planar Schottky-barrier diodes

A novel design of a subharmonically pumped millimeter-wave mixer operating at room temperature was developed and realized. The double sideband conversion loss and mixer noise temperature were measured to be 6.2 dB and 930 K, respectively, at a local oscillator frequency of 73 GHz and an IF of 1.5 GHz. These results are comparable to the best published results measured for subharmonically pumped mixers at similar frequencies. The mixer shows good performance even at IF's up to 9.5 GHz resulting in a useful RF range from 136 GHz to 156 GHz. For the first time a subharmonically pumped millimeter-wave mixer was designed without the use of any scale model measurements or other high-frequency measurements. The whole design process occurred on the basis of computer simulations. Two single low-capacitance planar air-bridge type Schottky-barrier diodes are used as the mixing elements     

92 GHz dual-polarized integrated horn antennas

A dual-polarized two-dimensional imaging array was designed for millimeter-wave applications. The dual-polarized design consists of two dipoles perpendicular to each other and suspended on the same membrane inside a pyramidal cavity etched in silicon. The dual-polarized antenna is fully monolithic with room available for processing electronics. The IF or video signals are taken out through a novel bias and feeding structure. The measured polarization isolation is better than 20 dB at 92 GHz, and the orthogonal channels show identical far-field patterns. The antenna is well suited for millimeter-wave polarimetric synthetic aperture radars (SARs) and high-efficiency balanced-mixer receivers     

Monolithic rat-race mixers for millimeter waves

In this paper, we report on fully monolithic millimeter-wave Schottky-barrier diode (SBD) down-converters with an IF amplifier using heterojunction bipolar transistors (HBT's). A rat-race circuit is used for the mixer, and is analyzed using a harmonic-balance simulator. The measured conversion gain and the isolation are 7.1 and 29 dB in the V-band design, and 8.0 and 25 dB in the W-band design, respectively. The conversion gains are matched well with the circuit simulation     

The Aerospace Low-Noise Millimeter-Wave Spectral Line Receiver (Short Papers)

A multichannel millimeter-wave receiver has been designed and built to study narrow-band signals from the natural background. This receiver is used with the Aerospace 4.6-m millimeter-wave antenna at El Segundo, CA. It is a superheterodyne mixer receiver which will tune over the 70-120-GHz frequency range with a system noise temperature of ~ 500 K (DSB). The spectral line receiver includes the RF system, the IF system, the local oscillator (LO) phase-locking system, the multichannel filter receivers, and the data processing system. This short paper describes the design and operation of the spectral line receiver and provides a sample of the results obtained.     

A 94 GHz planar monopulse tracking receiver

This paper describes the design, fabrication and measurements of a 94 GHz integrated monopulse receiver with IF beam control. The receiver is integrated on a single chip, and is based on a 23 GHz local oscillator driving four separate phase-coherent 94 GHz subharmonic mixers. The resulting IF signals are takeoff-chip to a IF monopulse processor, which produces sum and difference monopulse patterns for the elevation and azimuth coordinates. Voltage-controlled phase-shifters in each of the IF channels allow the monopulse patterns to be electronically steered. All of the receiver circuits are realized using uniplanar coplanar-waveguide (CPW), slot lines and coplanar striplines (CPS). These features result in a compact, low-cost system suitable for tracking systems operating in poor visibility conditions, as well as in collision avoidance receivers for automotive applications. To our knowledge, this work represents the first demonstration of a fully integrated millimeter-wave subsystem to date     

Millimeter-wave generation and characterization of a GaAs FET byoptical mixing

Coherent mixing of optical radiation from a tunable continuous-wave dye laser and a stabilized He-Ne laser was used to generate millimeter-wave signals in GaAs FETs attached to printed-circuit millimeter-wave antennas. The generated signal was further down-converted to a 2-GHz IF by an antenna-coupled millimeter-wave local oscillator at 62 GHz. Detailed characterizations of power and S/N under different bias conditions have been performed. This technique is expected to allow signal generation and frequency-response evaluation of millimeter-wave devices at frequencies as high as 100 GHz     

Backward Diodes for Low-level Millimeter-Wave Detection

Backward diodes (low peak current tunnel diodes) suitable for small-signal detection applications in the millimeter-wave region have been fabricated from n-type germanium. The diodes have the dimensions and geometry of point-contact diodes. For millimeter-wave signal levels below about - 20 dbm, the current sensitivity of these units is an order of magnitude greater than that of selected existing diodes for this frequency range. When employed as millimeter-wave frequency converters, the minimum conversion loss is comparable to that of conventional diodes, but the beating oscillator power requirements may be somewhat reduced. The diode noise factor at megacycle IF frequencies is comparable to that of conventional units, and in the low audio IF range it is expected to be markedly decreased. The fabrication of these diodes is described and their initial performance at selected frequencies from 11 Gc to 300 Gc is discussed.     

改进的基于多倍频的单边带调制ROF全双工系统

利用单边带调制技术,设计了一种改进的毫米波光纤传输系统,进行了系统色散分析及仿真实验.该系统在中心站通过设置相位调制器的偏置电压,使调制器产生的奇数边带被抑制,采用滤波器滤出其中的一个二阶边带.基带信号经过中频调制形成副载波,再将此副载波通过单边带调制到二阶边带上;在基站,通过带通滤波器滤出上行链路所需的光载波.用该单...     

Millimeter-Wave Heterodyne Six-Port Receiver： New Implementation and Demodulation Results

This paper presents a new implementation of a millimeter-wave heterodyne receiver based on six-port technology.The six-port model is implemented in Advanced Design System(ADS) using S-parameter measurements for realistic advanced simulation of a short-range 60 GHz wireless link.Millimeter-wave frequency conversion is performed using a six-port down-converter.The second frequency conversion is performed using conventional means because of low IF.A comparison between the proposed receiver and a conventional balanced millimeter-wave mixer shows that the proposed receiver improves conversion loss and I/Q phase stability over the local oscillator(LO) and RF power ranges.The results of demodulating a V-band quadrature phase-shift keying(QPSK) signal at a high data rate of 100 Mb/s-1 Gb/s are discussed.The results of a bit error rate(BER) and error vector magnitude(EVM) analysis prove that the proposed architecture can be successfully used for wireless link transmission up to 10 m.