Reflectionless Filtering 90° Coupler Using Stacked Cross Coupled-Line and Loaded Cross-Stub

Yu, Wei; Rao, Yunbo; Qian, Huizhen Jenny; Luo, Xun

doi:10.1109/lmwc.2020.2986155

Cited by 22 publications

(11 citation statements)

References 33 publications

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“…In (6), fr.max is a user-defined maximum allowed misalignment between the actual and the intended operating frequency (or frequencies), r denotes a user-defined penalty factor, and fr refers to is a regularization function whose definition is problem specific (cf. (7). As it can be seen, the regularization term increases the primary objective function in a manner proportional (through a user-defined factor r)…”

Section: B Frequency-related Regularization Concept and Benefitsmentioning

confidence: 99%

“…A remark should be made that the proposed regularization approach is capable of handling several different minima at different target frequencies. This may be necessary e.g., when optimizing e.g., multi-band transformers and it merely requires to reformulate the regularization function (7). In the reformulated regularization function instead of the frequency vectors of (7), the vector of the target operating frequencies and the vector of the actual resonant frequencies at current design x (that have extracted from the EM-simulated response), respectively, need to be inserted.…”

Section: B Frequency-related Regularization Concept and Benefitsmentioning

confidence: 99%

“…Although the development of microwave circuits traditionally relies on theoretical and equivalent network models [1]- [4], the importance of electromagnetic (EM)driven design has been continuously growing over the years [5], [6]. On the one hand, EM analysis is indispensable for reliable performance evaluation that accounts for the phenomena that cannot be reliably quantified by simpler representations [7]. On the other hand, simulation models are frequently used in the design process itself, e.g., for tuning geometry parameters [8] or uncertainty quantification [9], [10].…”

Section: Introductionmentioning

confidence: 99%

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Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization

2020

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Electromagnetic (EM)-driven optimization is an important part of microwave design, especially for miniaturized components where the cross-coupling effects in tightly arranged layouts make traditional (e.g., equivalent network) representations grossly inaccurate. Efficient parameter tuning requires reasonably good initial designs, which are difficult to be rendered for newly developed structures or when redesign for different operating conditions or material parameters is required. If global search is needed, due to either the aforementioned issues or multi-modality of the objective function, the computational cost of the EM-driven design increases tremendously. This paper introduces a frequency-related regularization as a way of improving the efficacy of simulation-based design processes. Regularization is realized by enhancing the conventional (e.g., minimax) objective function using a dedicated penalty term that fosters the alignment of the circuit characteristics (e.g., the operating frequency or bandwidth) with the target values specified by the design requirement. This leads to smoothening of the objective function landscape, improves reliability of the optimization process, and reduces its computational cost as compared to the standard formulation. An added benefit is the increased immunity to poor initial designs and multi-modality issues. In particular, regularization can make local search routines sufficient in situations where global optimization would normally be necessary. The presented approach is validated using two miniaturized circuits, a rat-race and a branch line coupler. The numerical results demonstrate its superiority over conventional design problem formulations in terms of reliability of the optimization process. INDEX TERMS Microwave design; miniaturized passive components; design optimization; EM-driven design; gradient-based search; regularization.

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Section: B Frequency-related Regularization Concept and Benefitsmentioning

confidence: 99%

Section: B Frequency-related Regularization Concept and Benefitsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization

2020

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“…In [32], the main banpass channel, which consists of a bandpass filter and supur-lines, together with the bandstop auxiliary channel lead to a wideband bandpass filter with broad stopband and ultra-wideband reflectionless at the input port. Similarly, a wideband reflectionless filtering coupler is presented in [33] To achieve symmetrical two-port reflectionless properties using the complementary diplexer architecture, auxiliary absorptive circuits need to be loaded at both the input and output ports [22], [34]. The theoretical analysis demonstrates symmetrical quasi-reflectionless properties and provide general guidance in terms of implementations using acoustic, lumped-element, transmission-line, etc.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

Wu¹,

Li²,

Liu³

2020

Preprint

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High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with the presented absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-of-band rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

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“…In [33], the main bandpass channel, which consists of a bandpass filter and spur-lines, together with the bandstop auxiliary channel lead to a wideband bandpass filter with broad stopband and ultra-wideband reflectionless characteristics at the input port. Similarly, a wideband reflectionless filtering coupler is presented in [34].…”

mentioning

confidence: 99%

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-Band Rejection

Liu

2020

IEEE Access

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High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-ofband rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

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Reflectionless Filtering 90° Coupler Using Stacked Cross Coupled-Line and Loaded Cross-Stub

Cited by 22 publications

References 33 publications

Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization

Improved-Efficacy Optimization of Compact Microwave Passives by Means of Frequency-Related Regularization

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-Band Rejection

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