Third-Order Intermodulation Distortion and Gain Compression in GaAs Fet's

A simple unilateral nonlinear circuit model of a GaAs FET is used in the analysis of the third-order intermodulation distortion and gain compression characteristics of a single-stage amplifier. Expressions are obtained for these characteristics, relating them to the input power level and to the device load admittance. The expressions are illustrated with contours on the load admittance plane of constant intermodulation distortion ratio, intercept point gain compression, AM-to-PM conversion, and output power, and as output power versus input power plots for fixed terminations. Agreement with experimentally measured distortion characteristics is good.     

有源滤波器的非线性交调失真

本文用频域交调波平衡法，分析了有源滤波器的非线性交调失真，计算和测量结果一致。     

抑制空间行波管三阶交调失真的信号注入技术

为了抑制空间行波管非线性特性产生的交调失真,本文通过理论分析、计算机仿真和实验验证,分别研究了谐波、交调和混合信号注入技术对空间行波管三阶交调（IM3）分量的抑制情况。实验结果表明：IM3注入技术能够得到25.2 dB的IM3最大抑制量,明显大于谐波注入技术的12.7 dB,两者对IM3失真分量的抑制效果都很良好,且就窄带空间行波管而言IM3注入技术比谐波注入技术更具优势。通过进一步仿真实验,证明双IM3注入技术可以在两个IM3频率处分别产生46 dB和53 dB的最佳抑制量,且混合注入谐波和交调信号也能最大抑制36.9 dB。     

A Nevv Method of Third-Order Intermodulation Reduction in Nonlinear Microwave Systems

Third-order intermodulation distortion (IMD (3)) of some microwave systems has been analyzed using Vollterra series. In this paper, theoretical results which have been calculated with a nonlinear FET model show that third-order intermodulation prodgcts of two input signals at f/sub 1/ and f/sub 2/ can be reduced by several orders of magnitude (in fact, theoretically, IMD (3) should be reduced to zero), with a low-frequency feedback at f/sub 1/- f/sub 2/, when the amplitude and the phase of this feedback are correctly chosen. To verify this prediction, a circuit has been realized and measurements have been made on a one-stage FET amplifier. First results confirm our analysis. Experimental measurements show a 12-dB decrease of intermodulation products with our method.     

Harmonic and Intermodulation Distortion Output of a Radio-Frequency Plasma Capacitor

This letter investigates the harmonic and intermodulation distortion behavior of a prototype plasma capacitor proposed for use as a radio-frequency control device. Experiments at a fundamental frequency of 900 MHz show second and third order harmonic output as high as -29 dBc and -35 dBc respectively for a 20 dBm input. Intermodulation distortion measurements are also performed at difference frequencies of 200 kHz and 1 MHz.     

Large Signal Analysis of Harmonic and Intermodulation Distortion in Switched-Current Audio Memory Cells

Closed-form expressions are presented for the harmonic and intermodulation performance of SI audio memory cells excited by large amplitude multisinusoidal current signals. Effects of the threshold-voltage mismatch, the output conductance and the clock-injection are taken into consideration. The results show that under certain conditions, the second-harmonic components resulting from these three sources may be out of phase and thus cancellation, resulting in minimum distortion, may result.     

Optimization of Nonlinear Transmission Lines for Harmonic Generation: The Role of the Capacitance-Voltage Characteristic and the Area Effect

In this paper, nonlinear transmission lines (NLTLs) periodically loaded with symmetric voltage dependent capacitances are investigated by means of computer simulation. Specifically, we have studied the role that the C-V characteristic plays on the performance of NLTLs as frequency multipliers. The main conclusion of the work is that the area under the C(V) curve is a key parameter for the optimization of conversion efficiency. This result is interpreted on the basis of soliton like propagation in NLTLs.     

Intermodulation Distortion in CMOS Attenuators and Switches

Gain control elements are widely used in communication systems both to limit the incident power to the circuitry and to control the amplitude of the transmitted signal. Attenuators are one way of controlling the signal amplitude. The distortion performance of common CMOS attenuator topologies is investigated in this work. CMOS device equations that model the device in different regions of operation and which also model short channel effects are used for calculating distortion performance. Calculated distortion is compared with simulation results and experimental data, and qualitative explanations of the distortion curves as well as the deviation between different sources of data are given. Potential improvements in linearity performance of attenuators via circuit design techniques have also been discussed     

无线通信系统中三阶交调的研究

随着通信行业的快速发展,移动通信对固定带宽内传输的信息容量的需求越来越大,而交调失真尤其是三阶交调,对信号容量以及接收灵敏度有着巨大的影响。文章主要对无线通信系统中三阶交调展开分析研究。首先阐述了三阶交调对通信产生的影响,然后分别从生产方面和施工方面着手分析了天馈系统对三阶交调性能的影响,最后介绍了避免三阶交调的一些方法。     

Intermodulation Distortion of FDM-FM in Injection-Locked Oscillator

When an injection-locked oscillator is used to amplify a frequency division multiplexing-frequency modulation FDM-FM signal, second- and third-order distortions are found to exist. Explicit expressions are derived that give the signal-to-distortion ratio (NPR) as a function of the locking bandwidth, frequency offset, and various modulation parameters. These formulas are believed to be valid within the limits of the assumptions made.     

A Fast Algorithm for Sorting and Counting Third-Order Intermodulation Products

This paper presents a fast algorithm that performs a selective counting of the third-order intermodulation products generated when several carriers of various types are transmitted through a common nonlinear device. In deriving the algorithm, the carrier configuration and the frequency distribution of intermodulation products are both described by polynomials which are related to each other. The frequency distributions of third-order intermodulation products of the various kinds are then obtained with the aid of an FFT algorithm and a numerical method for solving a set of linear equations. When compared to a direct counting procedure, the proposed algorithm has presented a drastic reduction on the required Computational effort. This advantage is particularly important when the number of carriers sharing the nonlinearity is large. In an example with 1366 carriers of three different types sharing the nonlinearity, the CPU time was reduced from 7 h 46 min. down to 52 s.     

Intermodulation Distortion in Coupled-Resonator Filters With Nonuniformly Distributed Nonlinear Properties—Use in HTS IMD Compensation

We present a general procedure for calculating intermodulation distortion in coupled-resonator filters that allows one to predict the performance of a nonlinear filter as a function of the general nodal matrix defining the filter and the material parameters that cause the nonlinear behavior. It is valid for almost any type of nonlinear distributed effects, including those produced by high-temperature superconductors, nonlinear dielectrics such as ferroelectrics, or superconductor/ferroelectric bilayers, and it is valid when the spatial distribution of nonlinearities is not uniform. The procedure has been validated with experimental measurements in an eight-pole quasi-elliptic superconducting filter. Using this procedure, we have assessed a combination of materials with different types of nonlinear effects to partially or completely mitigate the filter's nonlinear response. This includes superconducting filters with a ferroelectric pre- or post-distorter stage or even with intermediate ferroelectric compensation stages     

Nonlinear Eulerian Analysis of Harmonic Generation in Traveling-Wave Tubes

A third-order nonlinear Eulerian hydrodynamic formulation was developed for the analysis of harmonic generation in helix traveling-wave tubes. The analysis was simple and computationally fast compared to Lagrangian analysis, and contrary to the existing belief, the theory could as well demonstrate the saturation behavior of the device. The performance of the theory was also found to be in close agreement with that of the Lagrangian analysis. The theory is expected to be useful as a first-hand design and simulation tool for microwave and millimetric wave traveling-wave tubes.     

Nonlinear Frequency-Modulation Distortion Analysis for VCO Based on Harmonic Balance Method

The analysis methods for the steady-state responses of the voltage tuning negative resistance oscillator (voltage-controlling oscillator, VCO) by the microwave nonlinear autonomous circuit harmonic balance method in millimeter-wave bands are studied in the paper. Firstly, the quasi-periodic characteristic of the steady-state response of the VCO modulated by a periodic signal is proved. Then, on the bases of the harmonic balance analysis and the inter-modulation balance analysis, a novel method for obtaining the steady-state tuning performance and the nonlinear frequency-modulation distortion characteristic of the VCO is presented. The total analysis process is aimed to a kind of NRD-guide Gunn diode VCO. The large-signal lumped equivalent circuit model of the millimeter-wave P⁺N-junction varactor is also given for explaining the algorithm and the principle of the NRD-guide VCO.     

Analysis and Improvement of Intermodulation Distortion in GaAs Power FET's

Tailoring of the doping profile is a powerful tool in reducing the intermodulation distortion (IMD) in GaAs power FET's. Reproducible and uniform preparation of the required profiles is a difficult task for epitaxial techniques. This shortcoming has motivated the present investigation of fabricating highly linear power FET's by ion implantation. An analytical divice model was developed for exploring the relationship between the active layer profile and the IMD. These calculations revealed a complex behavior in the variation of the distortion levels due to partial correlation between the contributions arising from nonlinear transconductance and output conductance. The device model was used to identify implant doses and energies for approaching an optimum active layer profile. Based on the results, a deep Se implant followed by a shallow compensating Be implant to reduce the doping level close to the surface was used in the device fabrication. The IMD of the transistors was measured by the two-tone method. Conventional epitaxial FET's with a flat doping profile were evaluated for comparison purposes. This comparison demonstrated that a 4-dB increase in the intercept point for the third-order intermodulation product can be realized by using the tailored implanted profile. The experiments demonstrated that the tuning conditions for maximum output power and minimum IMD are virtually identical for the implanted transistors, in contrast to the behavior of conventional devices with flat doping profiles. These performance advantages, coupled with the high levels of uniformity and reproducibility of doping parameters, show ion implantation to be a powerful technique in the fabrication of highly linear power FET's.     

Harmonic and Intermodulation Performance of the Semiconductor Bolometer

A mathematical model for the temperature dependence of the bolometer semiconductor resistance is presented. The model, basically a sine-series function, can easily yield closed-form expressions for the harmonic and intermodulation performance of the acquired interferogram voltage with large-amplitude multisinusoidal variations in the incident radiation. The special case of two-tone equal-amplitude incident radiation is considered in detail. The results show that the intermodulation components are always higher than the harmonic components of the same order. The results also show that the second-order intermodulation is always dominant and is higher than the second-harmonic component by about 6 dB. Moreover, the results show that for relatively small incident amplitudes of the incident radiation the ratio between the second- and third-harmonic components is almost equal to the ratio between the second-harmonic component and the fundamental. The results also show that the ratio between the amplitudes of the second- and third-order intermodulation components is almost equal to the ratio between the amplitudes of the second-order intermodulation component and the fundamental.     

新型非线性晶体--CsLiB6O10的倍频效应

介绍了新型非线性晶体———CsLiB6 O10 (CLBO)的非线性光学 (NLO)特性。用CLBO单晶在调QNd∶YAG激光器上实现了 2ω ,3ω ,4ω和 5ω谐波激光输出 ,转换效率分别为 6 0 % ,5% ,4 3%和8%。对影响倍频光转换效率的因素进行了讨论。     

Design of Dispersion Compensation and Nonlinear Distortion Self-compensation in Co-network Transmission Systems

Dispersion and nonlinear distortion have an effect on transmission performances of optical fiber transimission systems,The schemes of dispersion compensation and nonlinear distortion self-compensation in telecom-CATV co-network transmission systems are reported,followed by investigation on (1) the impact of dispersion compensation fiber (DCF) on fiber nonlinear effects with a cascade of erbium-doped fiber amplifiers (EDFAs) and different dispersion compensation schemes,(2) the impact of the complex on the total nonlinear distortion induced by EDFA gain tilt and the light source.As a result,dispersion compensation optimal scheme and EDFA negative gain tilt are suggested as a solution to dispersion compensation optimal scheme and EDFA negative gain tilt are suggested as a solution to dispersion compensation and the nonlinear distortion self-compensation.     

Intermodulation Effects in the Transmission of Voice-Activated SCPC/FM Carriers Through a Nonlinear Repeater

When several voice-activated SCPC/FM carriers are transmitted through a nonlinear satellite repeater, a large number of intermodulation products appear at the output. An analysis of the baseband effect of these products is presented, taking into account the random on-off pattern followed by each carrier, the random nature of the level of each modulating speech signal, and a precise definition of the carrier power spectral density which is conditioned on the fact that the carrier is on, assuming that this is the circumstance under which we want to examine interference effects on any particular carrier. The analysis shows that computing intermodulation baseband noise, simply by introducing a penalty factor into the noise that would result by treating intermodulation as if it were thermal noise, may lead to very conservative estimates of intermodulation effects. The paper is restricted to the situation in which all carriers have equal amplitudes, but the general analysis is still valid when this is not so. The extension is straightforward except for the difficulties in counting the number of products of each type.     

扬声器的互调失真测试分析探究

以扬声器的互调失真为研究对象,阐述Klippel和Soundcheck这两种测试仪对于互调失真的测试参数设置。将扬声器置于自由场环境中,使用相同的功率放大器和测试线路,馈以双音正弦激励信号,使用两种测试仪器测得的二阶与三阶互调失真存在差异。分析得出,测试结果差异是由于测试仪器软件内置计算公式差异所致。