射频开关及其在通信系统中的应用

主要针对无线通信系统中的身频电子开关进行分类讨论。总结了射频开关的带宽、插入损耗、隔离度、功率容量、开关速度、VSWR、功耗、使用寿命和尺寸等主要性能指标。讨论了铁氧体／机械开关、固态开关(PIN开关和FET开关)和MEMS开关的工作机理、各项技术指标以及优缺点。列表比较了各类开关。简述了开关矩阵在未来无线通信系统阵列天线中的作用及应用。最后,指出了射频开关的发展方向和动态。     

基于短波通信的射频前端电磁脉冲防护模块仿真与设计

随着通信系统面临的电磁工作环境越来越严峻,高功率容量、低插损、快响应时间的电磁脉冲防护模块对其射频前端电路的保护越发的重要起来.本文主要基于PIN二级管射频限幅的原理,构建了PIN二极管的时域等效电路模型,利用去嵌入阻抗场计算方法提取相应电路的S参数,优化设计匹配网络,并采用无源多级PIN二极管结构,设计了一个工作于0~200MHz,插入损耗小于0.15dB,驻波比小于1.4dB,响应时间小于1ns的短波通信电磁脉冲防护模块.结合PIN二极管时域等效电路模型,利用先进设计系统（Advanced Design System,ADS）仿真软件对电磁脉冲防护模块限幅性能进行仿真,并对加工出来的电磁脉冲防护模块进行了测试,结果验证了各项指标满足要求.     

一种新颖双馈电型PIN开关

微波光电二极管（PIN）开关速度和功率容量是相互矛盾的2个指标,为同时兼顾改善2个指标,结合半导体器件特性,采取PIN管芯两极同时馈电的设计形式（即双馈电型开关）,经过优化设计,研制出2 GHz～6 GHz单刀双掷PIN开关。与传统型开关电路相比,开关速度和功率容量都得到较好提升,为后续的工程应用奠定了基础。     

一种新型射频导热治疗仪的功率放大电路的仿真设计

信息时代的到来极大地改变了人类社会的生产、生活、工作和学习方式.射频功率放大器不仅在通讯系统中得到广泛应用,还逐渐被应用于其他领域内.本文为一种新型射频导热治疗仪所设计的大功率射频放大器电路,满足工作于射频低端.借助ADS仿真软件采用负载牵引技术的设计方式,通过对整体效率、功率增益、功率容量等一系列的对比.得出最佳输入、输出阻抗,并进行阻抗匹配电路的设计.在此基础上对整个功率放大电路进行谐波平衡优化仿真,显示达到良好的设计效果.     

超高频RFID前端SP4T的设计

分析了超高频射频识别系统时单刀多掷开关(SP4T)的要求.介绍了PIN管的基本结构和主要指标,建立了PIN管的微波等效模型.采用串-并联PIN管设计和制作了SP4T,并用ADS对设计电路进行了仿真和参数优化,分析了仿真和实测结果的差异.实际电路的插入损耗最大为1.42 dB,隔离度最小为25 dB,满足系统要求.     

一种基于肖特基二极管的大功率微波整流电路

为满足微波输能的大功率整流要求,提出了一种结合功分器和二极管阵列的整流电路,来提升微波整流电路的功率容量。该方法保持了较高整流效率,提升了整流电路的功率容量。根据需要调节功分器的分支数量,扩展了功率容量的覆盖范围。该电路结构紧凑,形式灵活,简捷高效。依此方法设计的整流电路,当输入功率在36dBm～42dBm时,均取得了大于60％的实测整流效率。在输入功率为41dBm时,整流效率达到了68％。电路的最高功率容量达到了43dBm 。     

PIN二极管简述

PIN二极管是射频电路中的一类重要元件，它与一般的由PN结构成的二极管的不同之处在于：PIN二极管在PN结之间还有一个未掺杂的本征半导体层--l层。     

基于射频隐身的自卫电子对抗功率控制

针对自卫电子对抗射频隐身条件下功率管控问题,分析了自卫电子对抗中压制性干扰与欺骗性干扰的射频隐身特性,讨论了自卫电子对抗有效干扰及射频隐身的关系并建立了射频隐身特性模型,提出了压制比有效边界、信干比有效边界的自卫电子对抗功率管控方法。依据电子对抗的"互闭环"特性,建立了基于功率管控前后截获距离比值的射频隐身表征因子,通过仿真证明了功率管控方法的有效性。     

一种新颖的实现大小功率切换的技术

针对大功率雷达发射组件大小功率切换技术的要求,利用环行器3个端口环行的特点,提出了一种新颖且更易于实现的大小功率切换技术。该技术只需一个PIN二极管单刀单掷的大功率射频开关,便可实现大小功率的切换,且射频开关无需通过大功率,只需对其进行反射,因此大幅降低了实现难度。同时,采用该技术研制了一部S波段发射组件,其大功率输出达到1 500 W以上,成功实现了大小功率的切换,且功率容量和切换速度均满足设计要求,具有较高的实用性。     

射频功率校准仪的GPIB接口开发

为了满足组建以PC为中心的射频功率自动校准系统的需求，提高射频功率校准及射频功率检测的效率。本文利用NAT9914GPIB接口专用芯片设计了一种以ARM为核心的射频功率校准仪的GPIB接口电路．并详细讨论了GPIB接口功能的软件实现方法，并给出了软件设计的流程图。基于此种方法设计的GPIB接口卡已成功应用于射频功率自动校准系统中，取得了良好的效果，实现了GPIB的基本功能。对相关工程技术人员有一定的借鉴作用。     

Establishing the minimum reverse bias for a p-i-n diode in ahigh-power switch

An important circuit design parameter in a high-power p-i-n diode application is the selection of an appropriate applied DC reverse bias voltage. Until now, this important circuit parameter has been chosen either conservatively, using the magnitude of the peak RF voltage, or by empirical trials to determine a possible lower value. The reverse bias requirement for a p-i-n diode operating in a high-power RF and microwave environment is explored. It is demonstrated that the minimum reverse bias voltage is equivalent to the p-i-n diode's self-generated DC voltage under similar RF conditions. A concise expression for this self-generated voltage is developed and experimentally verified and should assist the design engineer in more accurately selecting an appropriate minimum value for the applied reverse bias voltage setting     

Lateral insulated gate p-i-n transistor (LIGPT)-a new MOS gatelateral power device

A new insulated gate power device suitable for thin silicon-on-insulator (SOI) application is described and verified through two-dimensional numerical simulation. The lateral insulated gate p-i-n transistor (LIGPT) has a much superior current carrying capability than that of the lateral insulated gate bipolar transistor (LIGBT) because it conducts like a p-i-n diode. Because a new turn-off mechanism is employed, the LIGPT also demonstrates a very large gate turn-off capability. These two major advantages; coupled with other advantages such as latch-up free, make the LIGPT a very promising device for use in power integrated circuits on SOI     

P-I-N Diodes for Low-Frequency High-Power Switching Applications

The development of high-power low-frequency diodes, conditions for their operation, and results measured in actual circuits are described. Harmonic distortion at 500 kHz and 2 MHz has been found to decrease with increasing diode lifetime and forward-bias current. Large reverse bias voltages are necessary at low frequencies to keep the RF voltage swing from penetrating the forward conduction region. The improvement of p-i-n diode lifetimes with thicker I-layers or with planar construction has been studied and the performance of these diodes in a routing switch is reported.     

Distortion In p-i-n Diode Control Circuits

Traditionally, distortion in p-i-n diodes has been thought to be only a function of the carrier lifetime and frequency of operation. This understanding is based on empirical evidence and is not entirely accurate. This paper will discuss the origins of p-i-n diode distortion and study the effects of various devices parameters on distortion performance. Included in the investigation on single-diode circuits will be switching circuits and reflective attenuators. In switch circuits, the analysis shows that distortion can be minimized by maximizing the stored-to-charge resistance ratio in the diode. In attenuators, the analysis shows that maximizing the i-region thickness will minimize distortion, independent of the device carrier life-time. In attenuators where multiple p-i-n diodes are used (the bridged-tee and PI are discussed), maximizing the i-region thickness also minimizes the distortion, independent of carrier lifetime. The model accurately predicts distortion signal cancellation in both single and multiple p-i-n diode circuits.     

Comparison of GaAs MESFET and GaAs p-i-n diodes as switch elements

The Kurokawa-Schlosser quality factor Q̂ is used to compare the GaAs MESFET switch with the GaAs p-i-n diode switch. The MESFET device parameters are governed by the power handling capability and the specified pinchoff voltage, and the switch Q̂ is calculated from an approximate expression. The GaAs p-i-n has been characterized using a simple diode model which is derived from detailed simulations. The comparison for typical devices shows that the GaAs pin has the higher Q̂ and therefore should have improved characteristics as a switch in terms of insertion loss and isolation.     

The effects of an applied magnetic field on the oscillation of a silicon avalanche diode

The observed effects of an applied magnetic dc field on the oscillation of a p-i-n CW silicon avalanche diode oscillating near 11 GHz at room temperature are described. Near oscillation threshold, the applied magnetic field increases the RF power output significantly and the frequency of oscillation slightly, but has little effect at higher output levels.     

TRAPATT oscillations in a p-i-n avalanche diode

The characteristics of TRAPATT oscillations in a p-in diode are discussed and an approximate semi-analytical solution for the diode voltage waveform is derived when the diode current is a square wave. It is shown that a traveling avalanche zone is not necessary to generate a dense "trapped" plasma and that the boundary conditions prevent the trapped plasma from completely filling the depletion layer. Typical voltage waveforms and corresponding diode power, efficiency, and impedance at the fundamental and higher harmonics are presented. When the diode current is a square wave the diode does not necessarily exhibit a negative resistance at all higher harmonics. A computer program for TRAPATT oscillations in a p-i-n diode is described. Its running time is two or three orders of magnitude less than more exact time domain computer analyses. Typical results of diode power, dc to RF conversion efficiency, and required circuit impedances are presented for several different current waveforms which are composed of up to the seventh harmonic of a square wave and the first two harmonics of a half-wave sine wave. It is shown that high-efficiency oscillations are possible with diode currents composed of only the fundamental and one harmonic.     

Photovaractor for remote optical control of microwave circuits

A photovaractor for the remote optical control of microwave circuits was studied. The photovaractor was fabricated as a p-i-n photodiode placed in a pigtailed fiber optical module. The study of the impedance in the frequency range up to 3 GHz in darkness and under illumination has shown that the photovaractor capacitance strongly depends on the incident optical power. The capacitance variation of the photovaractor diode under illumination is discussed     

A 60-W Multicarrier WCDMA Power Amplifier Using an RF Predistorter

In this brief, we present a 60-W power amplifier that is linearized using an RF predistorter for multicarrier wideband code-division multiple-access (WCDMA) applications. The proposed RF predistorter is fully composed of RF or analog circuits, and it has a moderate memory effect compensation capability using a delayed third-order intermodulation (IM3) component path. It also includes the IM5 generation circuits and a compact IM3 generator that is capable of autocanceling for the fundamental component. The proposed RF predistorter was implemented and applied to a 60-W high-power WCDMA amplifier. For a four-carrier downlink WCDMA signal, the RF predistorter improved the adjacent channel leakage power ratio at a 5-MHz offset by 6.19 dB at an average output power of 48 dBm. The total efficiency of the system is as high as 13.6% at the same output power level. At an output power level of 60 W, the linearized power amplifier complies with the linearity specification of the WCDMA system.     

Thermally Induced Switching and Failure in p-i-n RF Control Diodes

This paper measures and analyzes a thermally induced, breakdown-like effect in p-i-n RF switching diodes. The effect is found to be due to thermally generated carriers increasing the I-region conductivity and loss. This is a positive feedback situation which, with increasing power levels, eventually causes the diode to switch to a low-impedance state. In the low-impedance state, further increases in temperature have a negative feedback effect on the absorbed power and hence this mode is stable with a very large hysteresis effect. Unfortunately, the high temperatures encountered in the low-impedance mode(~ 400°C) have a detrimental effect on diode reliability. The threshold power at which switching to this mode occurs can be increased somewhat by reverse biasing the diode or improving its heat sink.