宽带大动态范围自动电平控制技术研究

简要介绍了自动电平控制的作用及工作原理,深入分析了自动电平控制电路设计中的关键技术及难点,提出了一种应用于宽带大动态范围信号源中的自动电平控制技术方案,针对检波中根据输入信号的大小呈现的平方律线性特性,设计了双斜率对数放大电路,使对数放大器输出电压在大信号和小信号时始终与输入功率成线性比例关系,并对该电路进行了详细的理论分析,通过实验对设计的电路进行了验证,结果表明该设计稳定可靠,性能优良。     

宽带大动态中频AGC系统实现

在某宽带遥测接收机系统设计中,针对系统大动态范围设计要求,提出了一种宽带大动态中频AGC电路实现方案,该方案采用反馈型AGC结构,实现了带宽20 MHz下动态范围达60 dB的AGC系统。重点阐述了系统各模块的设计思路和技术指标,并对系统电路的工作原理进行了详细的分析,最后给出了系统测试结果。实测结果表明,该方案的AGC电路在20 MHz带宽下具有足够大的动态范围,且性能稳定,满足系统设计指标,并已在实际接收机系统中得到应用。     

用宽带模拟量光纤传输系统测量脉冲电磁场

介绍了一种在强电磁场环境中用于传输脉冲信号的宽带模拟量光纤传输系统。通过采用场效应管做前级放大与光电器件的非线性预校正,且提高级间RC耦合时间常数。该系统动态范围大,非线性失真小,带宽达到1 Hz~150 MHz,调整输入电路并配合天线能测量脉冲磁场或脉冲电场。给出了脉冲电磁场测量的耦合电路和测试实例。测试结果表明该系统很适用于宽带脉冲电磁场的测量。     

C波段宽带线性调频信号源的设计

宽带线性调频信号源在通信、雷达和仪器中有着广泛的应用.传统的线性调频信号产生方法有先天性的缺陷,本文介绍了一种基于DDS和PLL的C波段宽带线性调频信号源的设计方法.这种方法巧妙地使DDS和PLL进行优势互补,可产生带宽达1 GHz的高线性度线性调频信号.实验表明,这种方法能够完全补偿VCO的非线性,并且具有简单易行,可编程,可扩展,实用性强等优点,所产生的线性调频信号具有带宽宽、相位噪声低、频率分辨率高等特性,能够满足精密测距雷达对线性调频电路的技术要求.     

线性检波器高频特性及输出噪声的研究

在频域测试中,需要通过线性检波电路进行交直流的变换（AC/DC）,以研究待测系统的辐频特性。以运放为核心的线性检波器已被普遍使用,然而其高频响应较差。本文详细地讨论了影响线性检波电路高频特性的原因,并给出一种用共射一共集组合电路制作的线性检波器实用电路,其高频特性远远优于运放,还对两类电路的输出噪声进行了实测对比。     

一种性能优良的AGC电路

讨论了自动增益控制电路的工作原理及类型,重点讨论了一种性能优良的自动增益控制电路的工作原理及电路实现。该电路具有增益高、动态范围大、频带宽、电路结构简单、易于实现等特点,可用于光纤通信、微波通信、卫星通信等接收系统。     

一种宽带微波功率监测系统的设计

针对微波信号发生器中功率控制系统的高准确度和大动态范围要求,介绍了一种基于AD公司的宽带功率检测芯片AD8318的微波功率监测系统,给出了其工作原理及软硬件组成.通过对功率电压的测量,由DSP对接收数据进行滤波和线性插值处理,可实现对微波功率的精确控制.该系统的带宽可达8 GHz,动态范围达到75 dB,可用于微波功率...     

一种性能优良的AGC电路

讨论了自动增益控制电路的工作原理及类型,重点讨论了一种性能优良的自动增益控制电路的工作原理及电路实现。该电路具有增益高,动态范围大,频带宽,电路结构简单,易于实现等特点,可用于光纤通信,微波通信,卫星通信等接收系统。     

海洋环境噪声接收机的设计与实现

针对海洋环境噪声的测量,设计了一种低噪声、宽带、高动态范围的水声接收机。采用新一代真有效值转直流芯片AD8436实现噪声信号有效值的实时高精度计算,并通过微控制器调整程控增益放大器的增益码完成自动增益控制,同时自动记录系统增益值。该接收机具有良好的人机交互接口,既可在线传递系统的增益,又可按用户需求设定固定的增益。实验测试表明,该接收机的等效输入自噪声小等于3 μVrms,频率带宽为20 Hz~5.5 kHz,信号输入的动态范围大等于68 dB;且具有精度高、适应性强和电路性能稳定等特点,可较好地满足海洋环境噪声的测量与分析。     

可重构数据采集系统设计实现

讨论了可重构数据采集系统的概念和实现方案,采用基于FPGA的FMC标准化接口的子板、载板构成宽窄带信号、多通道多任务信号的采集和信号处理系统.子板完成采集功能,载板完成数字下变频、数据融合和高速光纤传输数据功能.给出设计分析及测试结果,该结果表明:窄带信号的信噪比满足系统大动态范围的要求,宽带信号满足大带宽及多带宽信号采样的要求.该系统相对于传统的固定模式采集系统有较高的性能,更灵活的配置,为现代雷达提供了一种高性能的数据采集的解决方案,具有广泛的应用前景.     

Bandwidth extension,linearity enhancement,and cost reduction techniques for continuous‐time channel‐select filters

Achieving a wide bandwidth in a conventional active‐RC filter requires large power consumption and is often accompanied by significant performance degradation. In this paper, a new structure to implement active‐RC continuous‐time filters and also a new frequency compensation scheme for the operational amplifiers that are the main building blocks of active‐RC filters are proposed. Exploiting these techniques increases the maximum possible bandwidth with lower power consumption in comparison with the conventional architectures, reduces die area, and enhances the dynamic range. The effectiveness of these methods has been verified by analysis and simulation of the conventional and proposed filters under identical conditions. Both the analytical investigations and extensive simulation results prove that the adopted techniques improve the performance of continuous‐time filters considerably in terms of bandwidth and linearity while reducing the die area. Simulations have been carried out in a standard 90‐nm CMOS process by using Advanced Design System (ADS), and the proposed filter features 11.08‐dB spurious‐free dynamic range improvement and 5.9 times bandwidth enhancement. Also, the total on‐chip capacitance is made 2.4 times smaller by using the new biquad structure. Copyright © 2016 John Wiley & Sons, Ltd.     

基于磁阻传感器的三维瞬态磁场记录仪的研制

随着智能变电站的发展,变电站二次设备的瞬态电磁干扰问题越来越引起人们的关注。为了研究变电站开关操作时的瞬态磁场,本文基于各向异性磁阻(AMR)传感器研制了一套高速大容量三维瞬态磁场记录仪。该仪器测量频带为DC-5MHz,动态范围20m Gs到6Gs,线性度大于97%,测量误差小于3%,存储深度大于50ms。测试和现场应用表明,该瞬态磁场记录仪在动态范围、线性度和抗电磁干扰性能等方面,基本满足变电站瞬态磁场测量要求,各项指标均达到设计要求。     

Photon Number Resolving Detector at Telecom Wavelengths: Charge Integration Photon Detector (CIPD)

A photon number resolving detector (PNRD) is the basic device for many optics applications, especially for developing optical quantum computer. The implementation of universal nonlinear quantum gates typically requires high quantum efficiency and a wide dynamic range up to a few tens of photons. We have developed a charge integration photon detector (CIPD) as a PNRD with a quantum efficiency of 80% and multiphoton measuring over ten photons at telecom wavelengths. This detector has a signal-to-noise ratio of 3 and operates at 40 Hz at present. In this paper, we introduce the principle of our CIPD and report the capability of detecting different types of photon statistics with a high linearity to incident photon numbers.     

Using MOS current dividers for linearization of programmable gain amplifiers

Two highly linear, digitally programmable gain amplifiers are presented and compared in terms of linearity, frequency, area and power consumption. High linearity and wide gain tuning range with moderate area consumption are the main benefits of both configurations. Furthermore, constant bandwidth is achieved by means of switched compensation capacitor arrays. Three‐bit prototypes were integrated in a 0.35 µm–3.3 V CMOS process with 2.5 V supply voltage. Experimental distortion levels are better than ?68 dB for 1 MHz and 1 V_p?p output signals in both configurations; hence, the suitability of the linearization technique based on MOS current dividers is shown. Copyright © 2007 John Wiley & Sons, Ltd.     

Electronically Tunable Filters

In this article, a brief introduction to the development of tunable filters was given. A classical design technique based on a combline filter approach was shown, where minimum degradation in passband performance could be obtained across a broad-tuning range. The fundamental disadvantages associated with the conventional resonator tuning approaches were also discussed, recognizing the importance of developing new techniques for realizing tunable microwave filters. It was shown that there is a possibility in realizing an electronically reconfigurable microwave filter based on parallel- coupled switched-delay lines, which possesses the important property of maintaining constant absolute bandwidth over almost an octave of tuning bandwidth. Furthermore, the filter has the ability to incorporate active switching elements in the filter circuit, without sacrificing its loss and linearity performance. With the exceptional linearity performance and power handling capability, the filter is readily adapted to poor environments. Although the use of p-i-n diodes as switching elements would result in large dc consumption, the approach could also be readily adapted for use with any switches, such as pHEMT or RF MEMS switches, to achieve extremely low power consumption. The integration of switchable couplings to enable both bandwidth and center frequency to be reconfigurable would be an enhancement.     

Differential amplifier with improved gain‐accuracy and linearity

A novel circuit design technique is presented which improves gain‐accuracy and linearity in differential amplifiers. The technique employs negative impedance compensation and results demonstrate a significant performance improvement in precision, lowering sensitivity, and wide dynamic range. A theoretical underpinning is given together with the results of a demonstrator differential input/output amplifier with gain of 12 dB. The simulation results show that, with the novel method, both the gain‐accuracy and linearity can be improved greatly. Especially, the linearity improvement in IMD can get to more than 23 dB with a required gain. Copyright © 2009 John Wiley & Sons, Ltd.     

CMOS current mirror with enhanced input dynamic range

A novel CMOS cascode current mirror configuration with enhanced input dynamic range is presented. The proposed mirror circuit combines the advantages of wide input swing, wide output swing and large output resistance capability, which make it attractive for practical application. Based on 0.18 µm MOS model parameters, HSPICE simulation results show that the input current ranges from 1 µA to 1 mA with large bandwidth for the proposed circuit. The simulation results confirm the theoretical prediction. Copyright © 2009 John Wiley & Sons, Ltd.     

Design of a robust PWM power amplifier using approximate two‐degree‐of‐freedom integral‐type control

A method is proposed for designing a robust controller for PWM power amplifiers, which are widely used as amplifiers and power supplies. The main technical requirements imposed on PWM power amplifiers are linearity in a wide frequency range and a well‐damped fast dynamic response in the presence of extensive load and DC power supply variations. Therefore, in order to satisfy the design specifications, namely, linearity in a wide frequency range and no overshoots during transients, an approximate two‐degree‐of‐freedom integral control structure is proposed and a design procedure for the robust controller is discussed. It is shown by some simulations and experiments that the designed controller shows especially good dynamic performance and effective disturbance rejection in the presence of external disturbances, that is, load and power‐supply variations. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(1): 68–77, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10102