一款JFET低噪声前置放大器的设计

在对级联网络及结型场效应管的噪声分析基础上,采用结型场效应管等分立元件设计了一款低噪声前置放大器实用电路。并对其幅频特性、输入阻抗和等效输入噪声进行了测量,结果表明其输入阻抗高达71Mn。等效输入噪声电压为0．7nV／√Hz,是一种适合于较高内阻传感器的较理想的低噪声前置放大器电路。     

低频低噪声测量放大器的设计

低频噪声是表征半导体器件质量和可靠性的一个重要敏感参数,为了能够测量电子器件低频噪声,使用分立器件SSM-2220组成偏置电路,由ADA4898-1构成前置放大器,采用噪声匹配变压器法设计一种测量低频低噪声的放大器。实验结果表明:在频率为80 k Hz以下,放大器输入端共模抑制比高出集成运放OP-37 228 d B,其系统的噪声系数低于前置放大器ADA-40752 0.3 d B,满足低频低噪测量放大器的设计要求。     

一款超低噪声前置放大器的设计

对于一款为低阻抗信号源设计用分立元件组成的前置放大器的低噪声设计要点作了较为详细的阐述,设计据级联放大器理论,重点是降低第一个晶体管的噪声系数,为此选择PNP型超β晶体管,并使之工作在低Uce,低Icl的微功耗状态,并采取低噪声阻容元件等措施.据此制作了电路并对其进行了测试.结果表明其等效输入噪声电压为0.12 nV/Hz,可称其为超低噪声前置放大器,可广泛应用于诸如锁相放大器等对噪声特性要求很高的微弱信号测试仪器中.     

高增益低噪声热释电红外探测器前置放大器设计研究

提出一种新的高增益低噪声热释电红外探测器电路模型.采用双极型结型场效应(BJFET),通过改变时间常数解决了热释电前置放大器输出信号弱和易受干扰的关键问题,理论推导了热释电电路的输出电流和电压响应,系统地分析了改进的前置放大器的噪声和温度特性.经实验验证:该电路实现了大电流、宽频带、高增益、低噪声等优化特性.     

低噪声前置放大电路设计

介绍了一种中、低频低噪声前置放大电路的设计方案.理论分析影响低噪声前置放大电路的因素;采用抑制噪声和直流漂移电路减小噪声干扰;并对设计电路进行测试和分析.以宽带前置放大电路为例,设计了低噪声的前置放大电路.     

低噪声的弹丸信号放大电路设计

针对传统放大电路设计出了一种用于红外光电立靶测试系统的前置放大器的电路,在设计中选用低噪声运算放大器和仪表放大器组成电路,同时论述了关于低噪声放大电路设计中的屏蔽和接地措施.     

基于光电二极管的前置放大电路噪声分析

在光电检测电路中信噪比是衡量电路性能的一个重要参数,因此有必要对前置放大电路进行噪声分析。首先给出了光电二极管和运算放大器的等效电路模型,并分析了光电二极管和运算放大器的噪声来源。然后采用分频段的方法计算前置放大电路的噪声,同时引入等效噪声带宽的概念。最后根据叠加原理和噪声理论,推导出了前置放大器的输出噪声计算方法。结果表明:该方法计算的结果与仿真结果相一致,误差较小。该方法的引入,对于元器件的选择和低噪声电路设计具有很好的参考价值。     

对数放大器在弱光检测中的应用

为提取弱光检测电路中淹没在噪声中的信号,通常使用高精度放大器尤其是对数放大器来提高电路滤除噪声的能力,其中以对数放大器LOG100为前置放大电路的光电检测电路效果最佳.基于这种电路,提出一种低噪声弱光电检测电路设计方案,以电子元器件相关参数的选择和依据,检测LOG100的输出效果.测量结果表明,输入光信号功率高于1 nW,LOG100噪声滤除性能良好,而低于1 nW时则输出噪声明显增强,可能导致A/D转换输出错误,不利于后续数据处理.     

低噪声应用中的DC—DC转换技术

通常在要求低噪声的场合不应使用DC-DC变换器,为了达到射频电路,低噪声放大器,读取前置放大器及其它敏感的模拟电路的性能要求而使用线性电源,所带来的结果是降低便携特性和缩短电池寿命。但是便携式电子产品的迅速发展导致了一些低噪声模拟电路和开关电源的简单结合。本文将探讨当严格的噪声和性能要求与供电电源冲突时如何综合考虑。     

CZT像素阵列核探测器的噪声分析

碲锌镉(CdZnTe)晶体是一种新型核辐射探测材料,在室温探测环境下对X射线及低能量伽玛射线具有较高的探测效率及能量分辨率.运用低噪声快速前放模块,分析晶体内部性能以及前置放大器对探测系统噪声的影响,建立了2×2碲锌镉像素阵列探测系统.实验结果表明,探测系统输出信号噪声小、脉冲无堆积,读出电路电子学噪声得到明显抑制,能...     

A Head-Mounted 24-Channel Evoked Potential Preamplifier Employing Low-Noise Operational Amplifiers

A simple circuit employing operational amplifiers yields an inexpensive low-noise biological amplifier. Design parameters are discussed and performance measured. When twenty-four of these amplifiers were incorporated in a head-mounted evoked potential preamplifier, noise increased while common mode rejection and stability decreased. These effects are explained and successfully controlled by minimizing source resistance and adding a simple feedback circuit.     

GaAsFET Mount Structure Design for 30-GHz-Band Low-Noise Amplifiers

This paper describes a GaAsFET mount design method for 30-GHz-band low-noise reflection-type amplifiers with the metal wall as a feedback circuit. Two examples of 30-GHz-band low-noise amplifiers are described; one with wide-band response and the other with high-gain response. The wide-band amplifier has 13-dB gain and 8.5-dB noise figure in the frequency range from 27.5 GHz to 29.1 GHz. The high gain amplifier has 15-dB gain and 9-dB noise figure in the frequency range from 27.7 GHz to 28.7 GHz. These results demonstrate the utility of this design approach.     

集成运算放大器同相和反相形式的E_n-I_n噪声分析和比较

本文通过分析和比较同相和反相放大器E_n-I_n噪声的特点,给出了若干新结果。本文方法在低噪声运放电路设计和运放噪声参数提取中都具有十分重要的意义。     

Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlingtou circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitivity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

Monolithic Integrated Circuits for Low-Noise Centimeter-Wave Amplifiers on an AlGaN/AlN/GaN/SiC Heterostructure

The results of designing low-noise broadband amplifiers on an AlGaN/AlN/GaN HEMT heterostructure are presented. In the investigations, two variants of low-noise amplifiers executed in a two-cascade circuit are considered and fabricated. The parameters of the fabricated monolithic integrated circuits of lownoise amplifiers are given.     

Investigation of Different Input-Matching Mechanisms Used in Wide-Band LNA Design

This paper analyzes different input-matching mechanisms used in designing the wide-band amplifiers in general, and the low noise amplifiers (LNA) in particular, and their corresponding noise impact. Among them, the most promising one is the reactive-feedback circuit configuration, which is a combination of high-frequency inductive feedback and low frequency capacitive feedback. In this paper the simulated result that both matched input impedance and low noise temperature T _n can be achieved simultaneously over a wide bandwidth in the single-ended low noise amplifier is proved mathematically and is well interpreted. This understanding of reactive feedback is crucial for the future development of ultra-wide-band low-noise amplifiers.     

Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlington circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitiyity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

220GHz低噪声放大器研究

基于IHP锗硅BiCMOS工艺,研究和实现了两种220 GHz低噪声放大器电路,并将其应用于220 GHz太赫兹无线高速通信收发机电路。一种是220 GHz四级单端共基极低噪声放大电路,每级电路采用了共基极（Common Base, CB）电路结构,利用传输线和金属-绝缘体-金属(Metal-Insulator-Metal, MIM)电容等无源电路元器件构成输入、输出和级间匹配网络。该低噪放电源的电压为1.8 V,功耗为25 mW,在220 GHz频点处实现了16 dB的增益,3 dB带宽达到了27 GHz。另一种是220 GHz四级共射共基差分低噪声放大电路,每级都采用共射共基的电路结构,放大器利用微带传输线和MIM电容构成每级的负载、Marchand-Balun、输入、输出和级间匹配网络等。该低噪放电源的电压为3 V,功耗为234 mW,在224 GHz频点实现了22 dB的增益,3 dB带宽超过6 GHz。这两个低噪声放大器可应用于220 GHz太赫兹无线高速通信收发机电路。