86,824 research outputs found
Physics-based large-signal sensitivity analysis of microwave circuits using technological parametric sensitivity from multidimensional semiconductor device models
No full textThe authors present an efficient approach to evaluate the large-signal (LS) parametric sensitivity of active semiconductor devices under quasi-periodic operation through accurate, multidimensional physics-based models. The proposed technique exploits efficient intermediate mathematical models to perform the link between physics-based analysis and circuit-oriented simulations, and only requires the evaluation of dc and ac small-signal (dc charge) sensitivities under general quasi-static conditions. To illustrate the technique, the authors discuss examples of sensitivity evaluation, statistical analysis, and doping profile optimization of an implanted MESFET to minimize intermodulation which makes use of LS parametric sensitivities under two-tone excitatio
Mathematical approach to large-signal modelling of electron devices
No full textA general purpose mathematical approach is proposed for the large-signal modelling of microwave electron devices (e.g. MESFETs, bipolar transistors, diodes, etc.). The mathematical model, which is based on mild assumptions valid both for field effect and bipolar devices in typical large-signal operating conditions, can easily be identified through conventional measurements and is particularly suitable for nonlinear microwave circuit analysis based on harmonic balance technique
A design method for DR-stabilized MESFET oscillators
No full textIn this paper a method is proposed for the design of DR-stabilized MESFET oscillators where several diferent design objectives, associated both to stability and output power, can simultaneously be taken into account. First, stability and self-starting capability of an oscillator are related to suitable performance indexes which are defined in the paper. Then an efficient procedure aimed at searching for an optimal compromise between opposing design requirements is described. The validity of the whole procedure and the performance indexes introduced has been investigated by considering the design of a microstrip parallel-feed back DR oscillator using a medium power GaAs MESFET
The vector-gradient Hough transform for identifying straight-translation generated shapes
No full textThe paper introduces the vector-gradient Hough transform (VGHT), a modified version of the gradient weighted Hough transform (GWHT), defined in vector space and able to exploit all the vector information of the gradient of luminosity. The new formulation, directly derived from the Radon transform, is analyzed and compared with the GWHT, in order to point out the improvement in selectivity provided by the VGHT in a strictly polar parametric space, without any relevant increase in computational complexity. This approach can be very suitable for identifying a specifically defined model of shapes in gray level images, ideally generated by a translation in the 2D space of a 1D luminosity profile. Finally, the suitability of the VGHT in real applications is shown with examples in the area of defect identification for automated visual inspection. © 1996 IEEE
A computationally efficient unified approach to the numerical analysis of the sensitivity and noise of semiconductor devices
No full textThe authors present a computationally efficient unified approach to the numerical simulation of sensitivity and noise in majority-carrier semiconductor devices that is based on the extension to device simulation of the adjoint method for sensitivity and noise analysis of electrical networks. Sensitivity and device noise analysis based on physical models are shown to have a common background, since they amount to evaluating the small-signal device response to an impressed, distributed current source. This problem is addressed by means of a Green's function technique akin to Shockley's impedance field method. To allow the efficient numerical evaluation of the Green's function within the framework of a discretized physical model, inter-reciprocity concepts, based on the introduction of an adjoint device, are exploited. Examples of implementation involving GaAs MESFETs are discusse
A mathematical modelling approach for the large-signal performance prediction of microwave electron devices
No full textA highly selective HT based algorithm for detecting extended, almost rectilinear shapes
No full textThe paper presents an highly selective algorithm for detecting extended and almost rectilinear shapes in digital images, in presence of structured and unstructured noise; it exploits the Gradient-based Hough Transform, followed by a special purpose correlation process in the parameter space. The paper discusses the algorithm and its application in a quality inspection task for detecting fabrication defects in mechanical pieces
The vector-gradient Hough transform
No full textThe paper presents a new transform, called vector-gradient Hough transform, for identifying elongated shapes in gray-scale images. This goal is achieved not only by collecting information on the edges of the objects, but also by reconstructing their transversal profile of luminosity. The main features of the new approach are related to its vector space formulation and the associated capability of exploiting all the vector information of the luminosity gradien
Physical noise modelling of majority-carrier devices: an adjoint-network approach
No full textA novel, two-dimensional technique for the physical noise modeling of monopolar devices, based on the impedance-field method, is presented. The impedance field is computed by means of an efficient approach based on the introduction of an adjoint problem, according to a method already successfully applied to noise analysis in lumped networks. The same approach can also be used for computing device sensitivities with respect to parameter variations. As an example, preliminary results are discussed relative to the application of the method to GaAs MESFET
Simulation and design for microwave class-C amplifiers through harmonic analysis
No full textIEEE TRANS. ON MICROWAVE THEORY AND TECHNIQUE
- …
