Harmonic and intermodulation performance of Josephson junctions

In this paper a simple mathematical model is presented for the inherent resistive nonlinearity of a Josephson junction. By incorporating this model in the RSJ model of the Josephson junction, series expressions are obtained for the harmonic and intermodulation performance of Josephson junctions irradiated by multisinusoidal signals. Special cases are considered where the series expressions can be reduced to simple analytical expressions.     

Harmonic and intermodulation performance of active integrated-optic waveguides

An empirical formula is developed for the static input/output optical characteristic of the active integrated-optic waveguide. Using this formula, closed-form analytical expressions, in terms of the ordinary Bessel functions, are obtained for the output optical components resulting from a modulated multisinusoidal optical input. Using these expressions the effect of the wavelength of the light input, the guide width, the modulation depth and the optical power for transperancy on the harmonic and intermodulation performance of the active integrated-optic waveguide can be studied.     

Harmonic and intermodulation performance of moderate inversion MOSFET transconductors

This article discusses the harmonic and intermodulation performance of moderate inversion MOSFET transconductors. The bulk of the nMOS transistor is tied to ground, at all levels of inversion, including moderate inversion and the transistor is operating in the saturation region where it behaves qualitatively as a constant current source. The current–voltage characteristic of the transistor is approximated using a Fourier-series model. Using this model, analytical expressions are obtained for amplitudes of the harmonics and intermodulation products resulting from multi-sinusoidal gate-to-source input voltages. The special case of a two equal-amplitude sinusoidal input is considered in detail and the results are compared with previously published results.     

Harmonic and intermodulation performance of double-gate CMOS inverting voltage amplifier

This paper presents a simple mathematical model for the transfer characteristic of the double gate (DG) CMOS inverting voltage amplifier. The model yields closed-form expressions for the amplitudes of the fundamental and distortion components of the output voltage resulting from a multisinusoidal input voltage for different scenarios and values of the bottom gates voltages. The special case of a two-tone equal-amplitude input voltage is considered in detail. The results show that the distortion performance of the DG-CMOS inverting voltage amplifier is strongly dependent on the bottom gates voltages and the amplitudes of the input sinusoids with the third-order intermodulation component dominating over the whole range of the input voltage amplitudes and different bottom gates voltages.     

Harmonic and intermodulation performance of MoS2FET- and GFET-based amplifiers

This paper presents a simple mathematical model for the output–input voltage characteristic of the graphene field effect transistor (GFET)- and the molybdenum disulfide field effect transistor (MoS₂FET)-based inverting amplifiers. The model, basically a Fourier series, yields closed-form expressions for the amplitudes of the harmonic and intermodulation components of the output voltage resulting from a multisinusoidal input voltage. The special case of a two-tone equal-amplitude input voltage is considered in detail. The results show that the harmonic and intermodulation performance of the complementary GFET- and the MoS₂FET-based inverting amplifiers is strongly dependent on the bias voltage and the amplitudes of the input tones with the third-order intermodulation component dominating over a wide range of the input voltage amplitudes.     

Harmonic and intermodulation generation in quantum-well diodes

A Fourier-series model describing the current-voltage characteristic of a quantum-well diode (QWD) is presented. Using this model, closed-form expressions are obtained for the harmonic and intermodulation performance of a QWD excited by a multisinusoidal voltage superimposed on a dc voltage.     

Harmonic and intermodulation distortion in oxide-confined vertical-cavity surface-emitting lasers

The nonlinear distortion in single and multimode vertical-cavity surface-emitting lasers (VCSELs) under analog modulation was studied both numerically and experimentally. A quasi-three-dimensional time domain model was used to simulate the second-order harmonic and third-order intermodulation distortion in typical GaAs-based oxide-confined VCSELs emitting at 850 nm. The model is based on fundamental interrelated physical processes involving the optical fields and carrier and temperature distributions with no parameter fitting to experimental results. The simulations show that for low modulation frequencies (<2 GHz), the distortion is strongly affected by spatial hole burning, and at higher modulation frequencies, the distortion is dominated by the relaxation oscillation effects. At intermediate frequencies the two effects often cancel, resulting in a significantly lower distortion. Due to mode competition, the multimode VCSEL shows a more unpredictable behavior in the low frequency region. Moreover, in this region, the distortion of an individual mode can be much higher than the distortion of the total output power demonstrating the importance of avoiding mode-selective losses in multimode applications. The general trends observed in the simulations are well reproduced in the experiments.     

Prediction of carrier to intermodulation performance

Closed-form expressions correlating the carrier to intermodulation performance, of two SCPC systems, with the simple two-carrier measurements are obtained. It is assumed that the high power amplifiers are exhibiting both amplitude non-linearity and AM/PM conversion characteristics. The high power amplifier is modelled by a quadrature model, which is mathematically represented by two sets of sine functions. Special eases are considered where curve fitting techniques, usually used to find the parameters of the sine function representations, can be totally avoided.     

Harmonic and two-tone intermodulation distortion analyses of theinverted InGa/InAlAs/InP HBT

Harmonic and two-tone intermodulation distortion analyses of the InGaAs/InAlAs/InP collector-up heterojunction bipolar transistor (HBT) are performed by a simple Ebers-Moll model. The parasitic elements of the equivalent circuit are extracted at zero bias by numerical optimization. A semianalytical approach is used to extract the intrinsic parameters of the small-signal equivalent circuit at nonzero bias points. Appropriate equations given by device physics are fitted to the bias variation of intrinsic parameters so that the Ebers-Moll model parameters can be extracted. Agreement between simulation and measurement of harmonic and intermodulation distortion is achieved     

On the computation of intermodulation products for a power series nonlinearity

A recently derived formula for intermodulation amplitudes in a power series nonlinearity involved a multiple summation with many terms. An iterative scheme is presented for performing the summation which greatly reduces computing time, thereby making the formula practical even for cases where the input amplitudes are not small.     

Prediction of the transient intermodulation performance of operational amplifiers

Closed-form expressions are obtained for the THD, THD-20 and MIM tests used to characterize the TIM performance of operational amplifiers and circuits of similar topology. Good agreement is observed between measured and calculated results. Using approximate formulae for Bessel functions, the calculations can be performed by using small programmable calculators.     

基于傅立叶级数法的互调产物一般特性分析

分析和讨论了非线性器件互调产物的一般行为特性.在已知传递函数的情况下,采用傅立叶级数法,推导了二载波情况下互调产物的幅度及其随阶数变化的一般表达式.针对两种典型的传递函数(分段线性软限幅器和光滑软限幅器),对二载波输入时的互调产物的幅度进行了数值计算.分析和数值结果表明:互调产物的幅度一般来说随阶数的增加而下降;高阶互调产物的下降行为本质上与传递函数的类型有关.     

Improved analysis of the intermodulation performance of ferroelectric thin-film and bulk-based varactors

In this paper, Fourier cosine series are proposed for representing the hard nonlinear dependence of the permittivity and conductance of a ferroelectric material on the DC bias voltage. Using these Fourier series representations closed-form expressions are obtained for the amplitudes of the fundamental and third-order intermodulation products generated when a exposing ferroelectric-based varactor to a DC bias voltage plus an equal-amplitude two-sinusoids signal. The results clearly show the strong and complicated dependence of the third-order intermodulation performance on the DC bias voltage, the temperature and the amplitude of the sinusoid. The results obtained suggest that the DC bias voltage and/or the temperature play an important role in deciding the nonlinear performance of the ferroelectric-based varactors.     

New single-parameter models for nonlinear electronic systems and its use in predicting intermodulation performance

Simple single-parameter models are presented for the instantaneous characteristics of nonlinear electronic systems. The models can easily provide closed-form expressions, in terms of the ordinary Bessel functions, for the amplitudes of the output components of the nonlinear systems excited by multisinusoidal signals. Moreover, being a single-parameter model, the nonlinear electronic circuit can be easily characterized using a set of measured data for the variation of the relative output third-order intermodulation over an appropriate range of input tone amplitudes of a two-tone equal-amplitude input signal.     

Numerical analysis of intermodulation interference in an optical coherent multichannel system

Coherent optical transmission techniques have a potential for use in ultra-wide-band coherent optical lans (UCOL's) in addition to long distance applications. They offer the possibility of extremely high total bandwidth by making simultaneous transmission of multiple wide-band signals possible. This paper reports on the numerical simulation of the performance of a heterodyne optical FDM system as a function of channel spacing. The channel interference due to intermodulation noise is discussed. A possible channeling arrangement with a spectral efficiency of 45 percent is described.     

Conversion gain and intermodulation performance of a GaAs HBT 50-950 MHz upconvertor

The authors report the measured performance of a single ended GaAs heterojunction bipolar transistor (HBT) upconverting mixer from 50 to 950 MHz, showing a conversion gain of 19.4 dB and output intermodulation intercept point (OIP/sub 3/) of +20.5 dBm with local oscillator drive power of 0 dBm. The measured results demonstrate the suitability of the HBT for use in low power consumption upconvertor circuits.<>     

Relationship between crossmodulation and intermodulation

When the frequency dependence of the 3rd-order distortions in a nonlinear system is taken into account, it is found that the well known fixed relationship between the (2q-p) inter-modulation product and the crossmodulation no longer exists. Owing to the same frequency dependence, the crossmodulation from n `unwanted? signals, e.g. in a c.a.t.v. system, is not simply n times the crossmodulation from a single unwanted signal, but the n components have to be added vectorially.     

Analytical expressions for intermodulation distortion of a MESFET small-signal amplifier using the nonlinear Volterra series

Using the nonlinear Volterra series representation, analytical expressions for the third-order intermodulation distortion power and intercept point for a MESFET small-signal amplifier are derived when its equivalent circuit is bilateral and includes the gate-to-drain capacitance (C_gd) explicitly as a nonlinear element. Previously developed analytical expressions treated C_gd as a linear element or incorporated it as a part of gate-to-source and drain-to-source capacitances (C_gs and C_ds). These new analytical expressions are then compared with experimental data and good agreement is obtained. The analytical expressions are also used to study the variation of intermodulation distortion with input power and frequency, and the effect of the individual nonlinear elements in the MESFET’s equivalent circuit.