Model order reduction of linear and nonlinear 3D thermal finite-element description of microwave devices for circuit analysis

Sommet, Raphaël; Chang, Christophe; Quéré, Raymond; Duême, P.

doi:10.1002/mmce.20105

Cited by 8 publications

(7 citation statements)

References 18 publications

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“…In our approach, ANSYS simulation software was solely used to extract the conductivity matrix K, the specific heat matrix M, and the load vector F using the excellent tricks proposed in [12]. Then, a reduced thermal equivalent model (τ i ; Ri) was obtained using the MOR method based on the Ritz vector approach detailed in [11,13].…”

Section: Finite Element Linear Formulation Of the Heat Equationmentioning

confidence: 99%

“…The procedure for generating orthogonal Ritz vectors leads to an m-by-n projection matrix as shown in [11], where m is the number of time constants retained for the final solution. m depends on the precision proposed for the reduced model (see, for example the influence of m in results presented Figure 5).…”

Section: Finite Element Linear Formulation Of the Heat Equationmentioning

confidence: 99%

“…In this paper, a comparison between the thermal time constants and thermal resistances obtained both using the analytical model [7] and numerical model (ANSYS software) coupled with MOR [11] was carried out. This work can be considered as an extended study of [7].…”

Section: Introductionmentioning

confidence: 99%

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Understanding the Thermal Time Constants of GaN HEMTs through Model Order Reduction Technique

Jakani

Sommet

Simbélie³

et al. 2021

Electronics

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This paper described a comparison between a numerical Finite Element Analysis (FEA) and an analytical approach in order to extract the thermal time constants and the thermal resistances of simple but realistic structures. Understanding the complex contribution of multidimensional thermal spreading, the effect of multiple layers, and the correlation with the heat source length is mandatory due to the severe mismatch of thermal expansion in different epitaxial layers and high operating temperatures. This is especially true on GaN HEMT (High Electron Mobility Transistor) with the continuous decrease of the gate length and the increase of the power density. Moreover, in this paper, we extracted the time constants with a Model Order Reduction (MOR) technique based on the Ritz vector approach with inputs coming from the FE matrices. It was found that the time constants obtained by an analytical solution and a model order extraction from FEA were exactly the same. This result validated the idea that our MOR technique provides the real time constants and resistances for our device structures and in this case unified the analytical world with the numerical one.

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Section: Finite Element Linear Formulation Of the Heat Equationmentioning

confidence: 99%

Section: Finite Element Linear Formulation Of the Heat Equationmentioning

confidence: 99%

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Understanding the Thermal Time Constants of GaN HEMTs through Model Order Reduction Technique

Jakani

Sommet

Simbélie³

et al. 2021

Electronics

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“…Consequently, the thermal properties of a solid state device and its thermal behaviour must be accurately described and predicted, becoming a key factor also in device reliability [19][20][21]. Consequently, the thermal properties of a solid state device and its thermal behaviour must be accurately described and predicted, becoming a key factor also in device reliability [19][20][21].…”

mentioning

confidence: 99%

“…20 Example of Ku-band PA designed by using a lumped (input) Wilkinson splitter/combiner and TL combiner (output). 21 Scheme of a two-way unequal Wilkinson power divider in microstrip form.…”

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confidence: 99%

Power Combining

general

2009

High Efficiency RF and Microwave Solid State Power Amplifiers

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Power amplifiers are employed in a variety of system applications, where the required power levels are largely different, varying from mW to kW [1,2]. Consequently, a wide variety of PA realizations results, from travelling-wave tube amplifiers in very high power systems [3,4], in satellite payloads or radars, to solid-state amplifiers for medium-low power systems [5,6], such as wireless communication handsets. The request for high output power levels is influencing device technologies adopted for PA module realization [7,8]. Prior to the development of solid state devices, microwave power amplification and generation were mainly based on the use of vacuum tubes [9, 10], including magnetron, klystron and travelling-wave implementations (TWTAs) [4,11]. These devices still remain in use at kilowatt levels, where solid-state devices cannot compete so far.Nevertheless, the development of high power microwave solid-state device technologies (GaAs HEMT or HBT, GaN HEMT, etc.) may offer an order-of-magnitude improvement in reliability and reduction in size, weight, and low-voltage power-supply requirements as compared to vacuum devices. However, the output power attainable from a single solid-state device is basically limited by thermal and impedance matching problems. To meet system requirements it is therefore mandatory to combine several devices, thus attaining higher power levels. Many power splitting/combining schemes have been investigated and developed, involving different technologies and propagation media, ranging from metal waveguides (cavities, microstrips, striplines, etc.) where the power is confined into a limited region, to open space configurations [12][13][14].Devices involved in power splitting/combining operations are referred to as power splitters/ combiners and they play a key role in the design of high power PA, while being also fundamental components in designing mixers [15], multipliers and oscillators [16,17], or other linear and nonlinear circuits [18]. Moreover, since the proposed schemes can often be adopted for both the tasks of power division and combination, the terms power combining and power splitting are usually adopted simultaneously or interchangeably. Due to their intrinsic reciprocal characteristic in fact, the same device can alternatively be viewed as a power combiner or as a power splitter, depending on the selection of its input and output ports.The key features of power splitting/combining devices are clearly their insertion loss (related to the efficiency), bandwidth and size. The techniques adopted for the optimization of device performance are strictly related to the type of splitting/combining structure and to the selected realization technology. High Efficiency RF and Microwave Solid State Power Amplifiers

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