宽带一体化接收前端技术的研究

本文构建了一个通用化、标准化、模块化的带射频接收前端,结合指标要求,进行了系统指标的规划及方案 的可行性论证,利用ADS 软件对其关键指标进行了仿真验证,阐述了宽带射端的设计方法及步骤。通过对各个功能模 块的设计、选择、及调试,最终在200MHz-3200MHz 的频率范围内,采用二次变频技术设计了一种超外差接收前端。 介绍了宽带射频前端系统仿真研究、接收机系统的方案选择、大动态范围接收机的实现接收机技术指标的计算与仿真 和发射机系统的设计与仿真。介绍了宽带一体化接收前端技术的系统设计与实现以及2～6GHz 通用接收机研究及关键 电路的设计与实验。     

前端机房射频链路的规划、设计与运维

紧密结合当前数字有线电视、高清互动电视系统传输的特点,通过对清远分公司前端机房射频链路的规划、设计,提出链路安全优化方案及运维分析,并在最后提出了几点建议,以供广大有线广播电视规划建设、运维工作者参考借鉴,批评指导.     

集成微波光子射频前端技术北大核心

微波光子射频前端具有频率覆盖范围大、工作波段和瞬时带宽可灵活重构、抗电磁干扰等优势,在泛在无线通信、软件无线电、雷达和电子战系统中有着广阔的应用前景。为进一步减小系统的尺寸和功耗以满足实际应用的需求,构建基于光子集成芯片技术的微波光子射频前端微系统势在必行。文章分析了集成微波光子射频前端微系统目前在器件层面和系统集成层面面临的挑战,并从高精细、可重构的光滤波器设计、混合集成系统架构设计和系统频率漂移抑制方案三个方面重点介绍了作者所在课题组开展的关于混合集成可重构微波光子射频前端的研究现状。     

关于IPQAM下移的前端射频系统优化方案分析

本文主要对多业务发展的形势下,广电网络采用IPQAM发展高清互动业务时,就分前端射频系统的优化改造方案进行了分析,并采用模型方式,探索如何科学、合理地规划前端射频系统,保障IPQAM系统的扩容和升级。     

CDMA直放站可变频射频前端的设计

设计了一种可变频射频前端,针对新一代具有数字处理功能的 CDMA 直放站而研发,可用于以解决“导频污染”、优 化网络为目的的 CDMA 直放站系统中.射频前端调制和解调通道采用零中频方式设计,并且本振部分可现场配置,输出频率 在一定范围内连续可变.介绍了此类CDMA直放站可变频射频前端的硬件设计思路,主要解决此类射频前...     

一种频率合成器的建模优化与电路设计

根据数模混合集成电路系统级和行为级快速验证的需求,设计了一种卫星导航系统射频接收机前端的频率合成器。传统行为级模型一般是基于理想环路进行参数提取,误差较大。为此,首先,分别利用MATLAB和Verilog-AMS对频率合成器建立理想行为级模型与非理想行为级模型,并根据行为级模型提取与优化的环路参数,采用SMIC 180 nm CMOS工艺设计仿真电路级频率合成器;其次,建立MATLAB噪声模型,对电路级各个模块的噪声进行拟合,评估频率合成器系统的整体噪声性能。所提出的频率合成器设计方法对电路级设计具有前瞻性的指导,并有助于电路级的设计优化。     

UHF大功率收发前端设计

射频收发前端电路是无线收发信机的重要电路之一,它对整个系统的噪声系数,动态范围等关键指标起决定性作用。文中具体分析了射频前端电路在无线通信系统中的重要性、射频收发前端的组成、工作原理、接收和发射部分的设计难点和重点。对关键技术指标进行了优化设计。设计了思维简洁、电路控制速度快的UHF大功率射频收发前端,并对方案进行试验改良。通过实验结果表明,该电路噪声系数达到3.2 dB,接收通道增益达到30 dB。发射通道输出功率≥40 dBm,三阶交调≤-18 dBc,试验结果达到预期目标。最后结合实际测试曲线,对实验结果进行进行了分析,并对现有方案提出了改进。     

链路复用的跳频收发机射频前端设计

针对便携式跳频电台,设计了一种收发链路复用的收发信机射频前端。该收发信机射频前端可以提高抗干扰能力,达到降低功耗、减小设备体积的目的。详细介绍了收发信机射频前端的设计链路和硬件电路实现,设计中收发链路均采用二次变频结构,输出和输入频率在110～512 MHz之间连续可变。最后,对射频前端进行性能测试,测试结果表明所设计的射频前端实现了低相噪、低杂散、带内波动小和高速跳频等指标。     

一种UHF频段无线数据传输系统接入点的射频前端

介绍了UHF(特高频)频段无线数据传输系统中接入点的一种射频前端。该前端包括调制器、上变频器、功率放大器、低噪声放大器、下变频器、解调器、频率合成器、增益控制和收发切换开关等电路。介绍了射频前端的实现方案以及关键部件的设计与测试。制作完成的射频前端集成在一块1 5 0mm×1 0 0mm的4层印制电路版上。该前端最大输出功率可达2W,接收灵敏度优于-100 dBm,收发切换时延小于1.5μs,满足系统指标要求。     

基于微波光子技术的一体化射频前端

针对传统射频前端技术中电子器件在频率、带宽方面受限的问题,研究了基于微波光子技术的射频前端。介绍了微波光子技术在宽带、低损和灵活等方面的优势,分析了光学辅助本振产生、多频变换以及微波光子交叉连接等技术,提出了一种基于微波光子技术的一体化射频前端。这种新型的前端架构具有高频宽带、灵活可重构的特点,适应不同的射频体制,并且能够有效降低系统的体积、重量和功耗。     

Review: Machine learning techniques in analog/RF integrated circuit design,synthesis, layout,and test

Rapid developments in semiconductor technology have substantially increased the computational capability of computers. As a result of this and recent developments in theory, machine learning (ML) techniques have become attractive in many new applications. This trend has also inspired researchers working on integrated circuit (IC) design and optimization. ML-based design approaches have gained importance to challenge/aid conventional design methods since they can be employed at different design levels, from modeling to test, to learn any nonlinear input-output relationship of any analog and radio frequency (RF) device or circuit; thus, providing fast and accurate responses to the task that they have learned. Furthermore, employment of ML techniques in analog/RF electronic design automation (EDA) tools boosts the performance of such tools. In this paper, we summarize the recent research and present a comprehensive review on ML techniques for analog/RF circuit modeling, design, synthesis, layout, and test.     

基于射频隐身的采样周期和辐射功率控制方法研究

为进一步提高雷达的射频隐身能力,合理分配相控阵雷达的工作参数,在目标跟踪时,对雷达的采样周期和辐射功率控制方法进行研究。首先,根据目标运动状态的不同,对雷达采样周期与辐射功率自适应设计方法进行分析,在满足系统跟踪性能要求的前提下,建立了控制参数的优化模型;然后,利用粒子群算法优化自适应采样周期和自适应辐射功率等参数,有效地降低了跟踪性能误差,提高了雷达系统的射频隐身性能。与传统的雷达采样周期和辐射功率算法进行了仿真比较,结果表明所提的算法取得了较好射频隐身效果。     

System-defined design and performance of RFICs for W-CDMA mobile radio terminals

Third generation wideband CDMA (W-CDMA) systems like UMTS will add broad-band data to support video, Internet access, and other high speed services for untethered devices. They are currently deployed in Japan and will be introduced in Europe in 2002. Despite sufficient RF performance has been assumed in the standardization bodies, especially in mobile devices the RF part is still a limiting factor for the overall system characteristics. Only an integral design approach including both RF and baseband functionalities makes it possible to achieve analog front-ends with sufficient performance. This paper reviews transceiver architectures with respect to W-CDMA and presents some of the recent silicon-based radio frequency integrated circuits for mobile terminals.     

ESD–RF co-design methodology for the state of the art RF-CMOS blocks

This paper describes an approach to design ESD protection for integrated low noise amplifier (LNA) circuits used in narrowband transceiver front-ends. The RF constraints on the implementation of ESD protection devices are relaxed by co-designing the RF and the ESD blocks, considering them as one single circuit to optimise. The method is applied for the design of 0.25 μm CMOS LNA. Circuit protection levels higher than 3 kV HBM stress are achieved using conventional highly capacitive ggNMOS snapback devices. The methodology can be extended to other RF-CMOS circuits requiring ESD protection by merging the ESD devices in the functionality of the corresponding matching blocks.     

RF beamforming for MIMO cognitive user

Using Multiple Input Multiple Output (MIMO) architecture in cognitive radio (CR) secondary users improves the system performance in terms of interference cancellation and data rate enhancement but at the expense of adding complexity and cost. A solution to reduce this complexity is employing radio frequency (RF) beamforming networks at the transmitter/receiver front-ends. In this paper, we consider a MIMO secondary user equipped with such RF beamforming network. Moreover, we find the transmit/receive optimum RF beamforming network for a MIMO spatial multiplexing system. We evaluate the performance of the optimally designed RF beamforming technique over a Rician channel via computer simulations. The simulation results are assessed for different RF beamforming structures and the number of primary transmitters which cause interference on the secondary receiver.     

一种快速实时工频信号采集处理的新方法

工频信号采集与处理在电力、通讯等诸多领域有着广泛的应用。文中详细论述了基于频率抽样滤波算法的工频信号采集处理方法,并提出了多频率抽样滤波方法,用以克服传统采集处理方法通带线性度差、带外衰减不理想、运算速度慢等缺点。在实际应用系统设计中证实该方法可靠有效、易于实现,特别适合单片机中工频采样数据的处理。     

一种新型扫频仪的设计

选用了一种基于DSP与FPGA结构的新型射频扫频仪的设计方案,重点讨论了其扫频信号源的设计.分析了频率合成技术的发展趋势,介绍了PLL技术和DDS技术的原理,并在此基础上给出了以PLL+DDS方式实现的扫频信号源设计.     

High-frequency CMOS amplifier with improved bandwidth performance

A high-frequency CMOS amplifier is proposed which can be used as a gain stage in RF front-ends. The circuit is based on a traditional transconductance amplifier unconventionally arranged to achieve both accurate input biasing and single-to-differential conversion. It takes advantage of an innovative approach to greatly improve frequency performance. Owing to this technique, the operating frequency of a basic amplifier in a 0.8 μm CMOS process could be extended from 290 to 650 MHz without affecting the gain     

Optimization of energy-constrained wireless powered communication networks with heterogeneous nodes

In this paper, we generalize conventional time division multiple access (TDMA) wireless networks to a new type of wireless networks coined generalized wireless powered communication networks (g-WPCNs). Our prime objective is to optimize the design of g-WPCNs where nodes are equipped with radio frequency (RF) energy harvesting circuitries along with constant energy supplies. This constitutes an important step towards a generalized optimization framework for more realistic systems, beyond prior studies where nodes are solely powered by the inherently limited RF energy harvesting. Towards this objective, we formulate two optimization problems with different objective functions, namely, maximizing the sum throughput and maximizing the minimum throughput (maxmin) to address fairness. First, we study the sum throughput maximization problem, investigate its complexity and solve it efficiently using an algorithm based on alternating optimization approach. Afterwards, we shift our attention to the maxmin optimization problem to improve the fairness limitations associated with the sum throughput maximization problem. The proposed problem is generalized, compared to prior work, as it seemlessly lends itself to prior formulations in the literature as special cases representing extreme scenarios, namely, conventional TDMA wireless networks (no RF energy harvesting) and standard WPCNs, with only RF energy harvesting nodes. In addition, the generalized formulation encompasses a scenario of practical interest we introduce, namely, WPCNs with two types of nodes (with and without RF energy harvesting capability) where legacy nodes without RF energy harvesting can be utilized to enhance the system sum throughput, even beyond WPCNs with all RF energy harvesting nodes studied earlier in the literature. We establish the convexity of all formulated problems which opens room for efficient solution using standard techniques. Our numerical results show that conventional TDMA wireless networks and WPCNs with only RF energy harvesting nodes are considered as lower bounds on the performance of the generalized problem setting in terms of the maximum sum throughput and maxmin throughput. Moreover, the results reveal valuable insights and throughput-fairness trade-offs unique to our new problem setting.

     

RF Class-E Power Amplifier Design Based on a Load Line-Equivalent Capacitance Method

In this research work, an alternative methodology to design radio frequency (RF) class-E amplifier is proposed and verified. The conventional design procedure starts with a switch idealization of the device and extraction of the output capacitance based on S parameter measurements. Since these ideal conditions lead to non-optimal values at microwave frequencies, an optimization procedure on these values, using a non-linear model of the device, has to be applied in order to obtain higher performance. Unlike this legacy procedure, the proposed method starts the design of the RF class E power amplifier with the non-linear model directly to determine a more representative value of the equivalent capacitance, and thereby considering all the non-ideal and non-linear features of the device.