Frequency-Domain Physics-Based Analysis of semiconductor devices by a Spectral-Balance approach

AbstractIn the paper, a method of estimation of parameters of Gaussian and non-Gaussian components in the noise signal of semiconductor devices in a frequency domain is proposed. The method is based on composing estimators of two spectra, corresponding to 1/fα noise (Gaussian component) and two-level RTS noise (non-Gaussian component). The proposed method can be applied for precise evaluation of the corner RTS frequency fRTS in the noise spectrum.

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Frequency-domain EBIC method for mapping of noise and instability regions in semiconductor devices

Materials Science and Engineering B ◽

10.1016/s0921-5107(01)01019-4 ◽

2002 ◽

Vol 91-92 ◽

pp. 239-243 ◽

Cited By ~ 2

Author(s):

A. Šatka ◽

D. Donoval ◽

F. Mika

Keyword(s):

Frequency Domain ◽

Semiconductor Devices ◽

Instability Regions

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A New Harmonic Balance Approach Using Multidimensional Time

Volume 10A: Structures and Dynamics ◽

10.1115/gt2020-16224 ◽

2020 ◽

Author(s):

Laura Junge ◽

Christian Frey ◽

Graham Ashcroft ◽

Edmund Kügeler

Keyword(s):

Frequency Domain ◽

Fundamental Frequency ◽

Harmonic Balance ◽

Fourier Transforms ◽

Cartesian Product ◽

Discrete Fourier Transforms ◽

Base Frequency ◽

Balance Approach ◽

Sampling Points ◽

The Common

Abstract Over the past years, nonlinear frequency-domain methods have become a state-of-the-art technique for the numerical simulation of unsteady flow fields within multistage turbomachinery as they are capable of fully exploiting the given spatial and temporal periodicities, as well as modelling flow nonlinearities in a computationally efficient manner. Despite this success, it still remains a significant challenge to capture nonlinear interaction effects within the context of configurations with multiple fundamental frequencies. If all frequencies are integer multiples of a common fundamental frequency, the interval spanned by the sampling points typically resolves the period of the common base frequency. For configurations in which the common frequency is very low in relation to the frequencies of primary interest, many sampling points are required to resolve the highest harmonic of the common fundamental frequency and the method becomes inefficient. In addition when a problem can no longer be described by harmonic perturbations that are integer multiples of one fundamental frequency, as it may occur in two-shaft configurations or when simulating the nonlinear interaction in the context of forced response or flutter, then the standard discrete Fourier transform is no longer suitable and the basic harmonic balance method requires extension. One possible approach is to use almost periodic Fourier transforms with equidistant or non-equidistant time sampling. However, the definition of suitable sampling points that lead to well-conditioned Fourier transform matrices and small aliasing errors is an intricate issue and far from straightforward. To overcome the issues regarding multi-frequency problems described above, a new harmonic balance approach based on multidimensional Fourier transforms in time is presented. The basic idea of the approach is that, instead of defining common sampling points in a common time period, separate time domains, one for each base frequency, are spanned and the sampling points are computed equidistantly within each base frequency’s period. Since the sampling domain is now extended to a multidimensional time-domain, all time instant combinations covering the whole multidimensional domain are computed as the Cartesian product of the sampling points on the axes. In a similar fashion the frequency-domain is extended to a multidimensional frequency-domain by the Cartesian product of the harmonics of each base frequency, so that every point defined by the Cartesian product is an integer linear combination of the occurring frequencies. In this way the proposed method is capable of fully integrating the nonlinear coupling effects between higher harmonics of different fundamental frequencies by using multidimensional discrete Fourier transforms within the harmonic balance solution procedure. The aim of this paper is to introduce the multidimensional harmonic balance method in detail and demonstrate the capability of the approach to simultaneously capture unsteady disturbances with arbitrary excitation frequencies. Therefore the well established aeroelasticity testcase standard configuration 10 in the presence of an artificial inflow disturbance, that mimics an upstream blade wake, is investigated. The crucial aspect of the proposed testcase is that a small ratio of the frequency of the inflow disturbance and the blades vibration frequency is chosen. To demonstrate the advantages of the newly proposed multidimensional harmonic balance approach, the results are compared to unsteady simulations in the time-domain and to state-of-the-art frequency-domain methods based on one-dimensional discrete Fourier transforms.

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A New Harmonic Balance Approach Using Multidimensional Time

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4049698 ◽

2021 ◽

Author(s):

Laura Junge ◽

Christian Frey ◽

Graham Ashcroft ◽

Edmund Kuegeler

Keyword(s):

Frequency Domain ◽

Fundamental Frequency ◽

Harmonic Balance ◽

Nonlinear Frequency ◽

Base Frequency ◽

Fundamental Frequencies ◽

Balance Approach ◽

Frequency Domain Methods ◽

Sampling Points ◽

The Common

Abstract Over the past years, nonlinear frequency-domain methods have become a state-of-the-art technique for the numerical simulation of unsteady flow fields within multistage turbomachinery. Despite this success, it still remains a significant challenge to capture nonlinear interaction effects within the context of configurations with multiple fundamental frequencies. If all frequencies are integer multiples of a common fundamental frequency, the interval spanned by the sampling points typically resolves the period of the common base frequency. For configurations in which the common frequency is very low in relation to the frequencies of primary interest, many sampling points are required to resolve the highest harmonic of the common fundamental frequency and the method becomes inefficient.To overcome the issues regarding multi-frequency problems described above, a new harmonic balance approach based on multidimensional Fourier transforms in time is presented. The basic idea of the approach is that, instead of defining common sampling points in a common time period, separate time domains, one for each base frequency, are spanned and the sampling points are computed equidistantly within each base frequency's period. Since the sampling domain is now extended to a multidimensional time-domain, all time instant combinations covering the whole multidimensional domain are computed as the Cartesian product of the sampling points on the axes. In a similar fashion the frequency-domain is extended to a multidimensional frequency-domain. In this way the proposed method is capable of integrating the nonlinear coupling effects between higher harmonics of different fundamental frequencies.

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