The kinetic power theorem for parametric, longitudinal, electron-beam amplifiers

A power theorem is developed for parametric, longitudinal, electron-beam amplifiers which may be considered as a generalization of Chu's well-known kinetic power theorem. The new power theorem is used to explore the limitations on noise performance of parametric electron-beam amplifiers. It is shown that the electron-beam noise does not impose a basic limit on the noise performance of a parametric electron-beam amplifier in the way a basic limit is imposed upon the noise performance of conventional longitudinal electron-beam amplifiers. The new power theorem can be employed for understanding the operation of parametric beam amplifiers in the same way as Chu's kinetic power theorem has been used for interpreting the opoeration of longitudinal beam amplifiers.     

微波固态反馈放大器的性能分析与自动设计

本文采用不定散射矩阵导出了串联、并联、混联和Mason反馈放大器的定散射矩阵显式表达式，提出了一种反馈放大器噪声参数的简化分析法，从而可快速分析微波反馈放大器的传输和噪声性能。在此方法的基础上，以知识库为支持，实现了微波固态反馈放大器的自动设计。     

Molecular amplification and generation of microwaves

This paper is a general introduction to the field of amplification and generation of microwaves using molecular rather than electronic processes. The basic physical properties of molecular systems as related to amplification are reviewed. The properties of molecular amplifiers, such as gain, bandwidth, saturation power, and noise figure are discussed and several specific types of amplifiers are described. These include the molecular-beam maser, the “hot-grid cell”, amplifiers excited by radio-frequency pulses and by “adiabatic fast passage”, and amplifiers based on multilevel molecular internal energy systems, including “optically pumped” amplifiers. Molecular amplifiers may add very little noise to the signal to be amplified: noise figures under 1 dB can be obtained. With suitable feedback, such amplifiers become oscillators of extremely high spectral purity. High gains can be achieved using regeneration, but bandwidths are relatively small. These range from the order of tens of kilocycles for amplifiers using a gaseous molecular system, to megacycles, using solids. Molecular amplifiers saturate at low input powers, of the order of microwatts. Variations of the devices discussed may provide a means of generating millimeter and submillimeter waves     

Intermodulation Performance of Solid-State UHF Class-C Power Amplifiers

In any frequency-division-multiple-access (FDMA) satellite communication system the control of intermodulation noise must be considered if all signals are amplified by a single nonlinear power amplifier in the satellite transponder. The subject of this paper is the use of Fourier-Bessel series expansion models in the prediction of the intermodulation performance of both traveling-wave-tube (TWT) amplifiers and solid-state class-C UHF amplifiers. Both theoretical and experimental results are described and compared. It is shown that in the case of the solid-state amplifiers a dynamic characteristic measurement technique must be used before reliable predictions can be achieved. A simple intermodulation noise reduction scheme is described for use with high-power efficient class-C solidstate amplifiers. It is demonstrated that a carrier-carrier-to-intermodulation noise power ratio improvement of 10 dB can be achieved with a minimal decrease in prime-power efficiency.     

Noise Figure Limit of L-band EDFAs

Erbium-doped fiber amplifiers (EDFAs) with high gain generally degrade the signal-to-noise ratio by at least 3 dB. In the conventional wavelength band, noise figures close to the so-called quantum limit can be obtained by strong pumping. Due to their lower average population in the metastable level, this limit is not reached by amplifiers designed for the long-wavelength band (L-band). In this paper, the lower noise figure limit is determined for such amplifiers. It has been found that the noise figure for typical gain values of about 30 dB can be very close to the quantum limit, whereas significantly larger noise figure values result for small amplifier gains. The lower limit decreases with increasing gain if the gain values are beyond 5 dB. In addition, the results reveal that low temperatures yield better noise figure.     

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.     

1480-nm pumped erbium-doped fiber amplifiers with optimized noiseperformance for AM-VSB distribution systems

Within analog video transmission systems, optical amplifiers have to display simultaneously good noise and output power performance because of the very stringent carrier-to-noise ratio requirements imposed by the AM-VSB modulation format. We show, theoretically and experimentally, that properly designed forward 1480-nm pumped erbium-doped fiber amplifiers can deliver +16 dBm saturated output power with noise parameter (n_sp/C_x) as low as 3.5dB. These amplifiers do not exhibit significant degradation of their noise performance when the input powers are as large as +3 dBm. These characteristics make 1480-nm pumped amplifiers suitable for AM-VSB transmission systems     

Measurement and analysis of phase noise generated fromsemiconductor optical amplifiers

The phase noise generated from traveling-wave semiconductor optical amplifiers is measured. It is found that the phase noise is strongly correlated with the intensity noise and has bandwidth of 600 MHz. Phase-noise formulas are derived for semiconductor optical amplifiers to explain such phase-noise characteristics. It is shown that the phase noise is induced by the carrier density fluctuation associated with the intensity noise and the spontaneous carrier recombination. For the coherent heterodyne DPSK system, the phase noise, instead of the intensity noise, is found to be the limiting factor on the number of repeater amplifiers     

FETs and HEMTs at cryogenic temperatures-their properties and usein low-noise amplifiers

Typical DC characteristics and X-band noise parameters are presented and qualitatively correlated wherever possible with other technological or experimental data. While certain general trends can be identified, further work is needed to explain a number of observed phenomena. A design technique for cryogenically cooled amplifiers is briefly discussed, and examples of realization of L-band, C -band, X-band, and K-band amplifiers are described. The noise temperature of amplifiers with HEMTs in input stages is usually less than half of that for all-FET realizations, setting new records of performance for cryogenically cooled, multistage amplifiers     

Gain and noise properties of small-signal erbium-doped fiberamplifiers pumped in the 980-nm band

The authors have experimentally and theoretically investigated the effects of detuning the pump wavelength on the gain and noise properties of small-signal, erbium-doped fiber amplifiers codirectionally pumped in the 980-nm band. While the pump wavelength can be varied over a wide range with little impact on the gain, a noise penalty is incurred. For amplifiers saturated by amplified spontaneous emission, it is possible to increase the gain by detuning the pump wavelength     

Noise characteristic of dye-doped polymer optical fiber amplifiers

The noise in polymer optical amplifiers is mainly derived from the amplification of spontaneous emission （ASE）. ha this paper, the noise characteristic of dye-doped polymer optical fiber amplifiers is studied. The propagation equations of ASE power and the rate equations of dye molecular concentration are found based on the energy level transition of dye. The noise characteristic of optical fiber amplifiers is given by solving above equations numerically, and the relationship between noise figure and parameters of optical fiber amplifiers is investigated in detail. The result shows that the noise figure of dye-doped polymer optical fiber amplifiers will not exceed 5 dB.     

A simple technique to evaluate the noise spectral density in operational amplifier based circuits using the adjoint network theory

We use the adjoint network theory to get quick estimates of the noise contributed by various elements in linear time-invariant opamp based circuits. The noisy operational amplifier is represented using a or with an input referred noise voltage and current source. The adjoint model for this representation is derived. This makes the noise analysis of operational amplifier based circuits very simple and the contribution of the operational amplifiers to the output noise can be obtained very often by inspection. The method is applicable to amplifiers, active RC and MOSFET-C filters. Examples of circuits analyzed include the universal active filter and gyrator topologies.     

Propagation of signal and noise in concatenated erbium-doped fiberoptical amplifiers

Signal propagation and noise accumulation in lightwave systems using saturated optical amplifiers as repeaters are analyzed. Numerical simulations of amplified spontaneous emission in concatenated erbium-doped fiber amplifiers indicate that a reach beyond 10000 km is possible with a 1.55-μm system in the absence of fiber nonlinearities. Distributed optical amplifiers are shown to have low noise, but require higher pump power than lumped amplifiers. Three operating modes of an amplifier lightwave system are identified and their relative signal power efficiency and noise performance are described     

Influence of the zero dispersion wavelength fluctuation on the gain and noise performance in dual-pump fiber parametric amplifiers

Because of the zero dispersion wavelength (ZDWL) random fluctuations, the gain and noise figures deteriorate in optical parametric amplifiers based on highly nonlinear fibers (HNLFs). The detrimental role of ZDWL fluctuations on the gain and noise performance in dual-pump fiber optical parametric amplifiers (FOPAs) is presented. Numerical investigations of noise figure (NF) for different fibers with random fluctuation are analyzed. The noise figures for different fibers are varying even if the random fluctuation is small. Through choosing HNLFs with low ZDWL fluctuation and large nonlinear coefficient, high-gain and low-noise performance can be obtained.     

Noise figure of saturated 1310-nm polarization insensitive multiple-quantum-well optical amplifiers

The noise figure degradation due to saturation by amplified spontaneous emission of high-gain 1310-nm polarization insensitive multiple-quantum-well optical amplifiers has been investigated systematically by studying amplifiers of different lengths. It is found that the intrinsic noise figure of 4 dB of a device with 20-dB single-pass gain is degraded to about 5 dB for a device having 36-dB single-pass gain. This degradation in noise figure is very modest, compared to results reported earlier for semiconductor optical amplifiers with bulk-gain media, illustrating the benefits of using a quantum-well gain medium in semiconductor optical amplifiers.     

Noise Statistics in Fiber Optical Parametric Amplifiers

In this paper, we show both theoretically and experimentally that the probability density function of the intensity of an amplified signal by parametric amplifiers subject to a pump with excess noise is highly asymmetric. This is due to the nonlinear relationship between the optical pump power and the parametric gain. Because of this, the relationship between the noise figure (NF) and the bit error rate (BER) is modified, compared with that predicted by the chi² theory, which is an effect that is notable at large NFs and low BERs. The difference in predicted BER can be of several orders of magnitudes between the correct theory and the chi² approximation in single-stage parametric amplifiers. We also show that in the limit of many cascaded parametric amplifiers, the statistics of the noise of an amplified optical signal approaches chi². Furthermore, the BER of a parametric amplifier is generally lower compared with erbium-doped fiber amplifiers for the same NF values if we assume quantum-limited amplification     

集成运算放大器参数时漂的1/f噪声预测方法

寿命试验和噪声测试结果表明,如果集成运算放大器的主要失效模式是输入偏置电流或失调电流随时间的漂移,则这种漂移量与运放的1/f噪声电流具有强相关性,二者近似呈正比关系。理论分析表明,这种漂移可归因于作为1/f噪声直接起源的氧化层陷阱对硅中电子的慢俘获作用。据此,提出了通过1/f噪声测量对集成运放特定参数时漂进行快速无损评估的方法。     

Low-noise monolithic amplifier design: Bipolar versus CMOS

Design of monolithic low-noise amplifiers in bipolar and CMOS technologies for matching a given signal source is presented. Noise matching conditions are derived for three different types of source impedance, i.e., resistive, capacitive, and inductive. Emphasis is put on the comparison of the best noise performance obtainable by the use of bipolar and CMOS approaches. It is shown that for a resistive source, low-noise amplifiers can easily be designed in both bipolar and CMOS technologies. While for capacitive and inductive sources, a CMOS approach yields better noise performance than a bipolar one. Measurement and simulation results on some amplifiers are presented which confirm the theoretical considerations.     

Noise temperature in distributed amplifiers

The subject of noise generation in certain types of RF amplifiers is treated. The different physical mechanisms by which noise is generated within the amplifier are discussed. Expressions for the "effective source noise temperature" are derived for distributed amplifiers of the maser, parametric, and tunnel type.     

放大器的相位噪声与噪声系数关系式理论推导

介绍了二端口器件放大器的噪声对相位噪声的影响,并从理论上对相位噪声和噪声系数之间的关系式进行了推导。