Aggressive Space Mapping Algorithm Research Articles

Design and Optimization of an S-Band MEMS Bandpass Filter Based on Aggressive Space Mapping.

Aggressive space mapping (ASM) is a common filter simulation and debugging method. It plays an important role in the field of microwave device design. This paper introduces ASM and presents the design and fabrication of a compact fifth-order microstrip interdigital filter with a center frequency of 2.5 GHz and a relative bandwidth of 10% using ASM. The filter used a double-layer silicon substrate structure and stepped impedance resonators (SIRs) and was optimized by ASM. After five iterations, the filter achieved the design specification, which greatly improves the efficiency of the filter design compared with the traditional method. It was fabricated on high-resistance silicon wafers by micro-electro-mechanical systems (MEMSs) technology, and the final size of the chip is 9.5 mm × 7.6 mm × 0.8 mm. The measurement results show that the characteristics of the filter are similar to the simulation results, which also shows the efficiency and precision of the ASM algorithm.

Investigation on temperature stability of MEMS silicon‐based sixth‐order stripline filter

A double-layer silicon-based stripline filter with a center frequency of 20.76 GHz and a bandwidth of 2 GHz was designed by using an aggressive space mapping (ASM) and fabricated with Microelectromechanical Systems (MEMS) technology. The measurements agreed well with simulation, showing efficiency and accuracy of the ASM algorithm. Over temperature range of −50 to 80°C, the filter's performance such as insertion loss, bandwidth and central frequency were investigated and discussed, and the measured frequency drift is −55.5 ppm/°C and the bandwidth variation is ±4% over temperature range of −50 to 80°C. At 150°C after 1000 h of aging test, although the insertion loss of the filter slightly increased from 2.18 to 2.4 dB and the passband ripple deteriorated, the stopband rejection performance improved.

Investigation on temperature stability of MEMS silicon‐based sixth‐order stripline filter

A double-layer silicon-based stripline filter with a center frequency of 20.76 GHz and a bandwidth of 2 GHz was designed by using an aggressive space mapping (ASM) and fabricated with microelectromechanical systems (MEMS) technology. The measurements agreed well with simulation, showing efficiency and accuracy of the ASM algorithm. Over temperature range of −50 to 80°C, the filter's performance such as insertion loss, bandwidth and central frequency were investigated and discussed, and the measured frequency drift is −55.5 ppm/°C and the bandwidth variation is ±4% over temperature range of −50 to 80°C. At 150°C after 1000 h of aging test, although the insertion loss of the filter slightly increased from 2.18 to 2.4 dB and the passband ripple deteriorated, the stopband rejection performance improved.

Design and fabrication of MEMS lowpass filter exploiting space mapping algorithm

AbstractA high‐performance microstrip lowpass filter with coplanar waveguide as the ports is proposed and analyzed. By cascading asymmetric hairpin resonators, a compact elliptic function low‐pass filter with wide stop band was realized. The filter was optimized using aggressive space mapping algorithm, and finally a filter with a cut‐off frequency of 11.8 GHz was obtained. Stop bandwidth with attenuation level better than −27 dB extends from 15.6 to 36 GHz. Also, the maximum insertion loss in the passband is 0.9 dB and the return loss is better than −22 dB. The filter is manufactured on the silicon wafer using micro‐electromechanical systems process, and the measured results in good agreement with the simulation results.

Power in Simplicity with ASM: Tracing the Aggressive Space Mapping Algorithm Over Two Decades of Development and Engineering Applications

The most widely used space mapping approach to efficient design optimization is the aggressive space mapping (ASM) algorithm. My purpose here is to present both a historical account and a technical reassessment of ASM, starting with the invention of the space mapping concept and continuing with a brief overview of the most fundamental space mapping optimization methods developed until now, within which ASM is framed. The article goes on to review over two decades of ASM evolution, in terms not only of the theoretical contributions directly incorporated into the ASM algorithm but also of the most significant engineering applications documented for ASM to date.

Automated design of bandpass filters based on open complementary split ring resonators (OCSRRs) using aggressive space mapping (ASM) optimization

AbstractThis paper is focused on the design of bandpass filters based on open complementary split ring resonators (OCSRRs) in microstrip technology. The filters are obtained by coupling the corresponding shunt resonators (OCSRRs) through admittance inverters (quarter wavelength transmission line sections). Different undesirable effects derived from the chosen topology are taken into account and are compensated at the design level. These effects include the reduction in bandwidth (caused by the narrowband functionality of the line sections acting as admittance inverters), and the presence of a spurious band above the filter passband. The proposed technique is based on the well‐known aggressive space mapping algorithm, which is a powerful tool for the synthesis and design of microwave components. The design of the OCSRR‐based filter is provided in a fully automated way as the main result of this paper. Copyright © 2015 John Wiley & Sons, Ltd.

Automated Design of Common-Mode Suppressed Balanced Wideband Bandpass Filters by Means of Aggressive Space Mapping

The automated and unattended design of balanced microstrip wideband bandpass filters by means of aggressive space mapping (ASM) optimization is reported in this paper. The proposed filters are based on multisection mirrored stepped impedance resonators (SIRs) coupled through quarter-wavelength transmission lines, acting as admittance inverters. Such resonant elements provide transmission zeros useful for the suppression of the common mode in the region of interest (differential filter pass band) and for the improvement of the differential-mode stopband (rejection level and selectivity). Due to the limited functionality of the inverters, related to the wide fractional bandwidths, the automated filter design requires a two-step process. With the first ASM, the filter schematic satisfying the required specifications (optimum filter schematic) is determined. Then, the layout is synthesized by means of a second ASM algorithm. Both algorithms are explained in detail and are applied to the synthesis of two filters, as illustrative (and representative) examples. With this paper, it is demonstrated that the two-step ASM optimization scheme (first providing the optimum schematic and then the layout), previously applied by the authors to wideband single-ended filters, can be extended (conveniently modified) to common-mode suppressed differential-mode bandpass filters. Thus, the value of this two-step ASM approach is enhanced by demonstrating its potential for the unattended design of complex filters, as those considered in this paper.

Synthesis of slow-wave structures based on capacitive-loaded lines through aggressive space mapping (ASM)

This article is focused on the automated synthesis of slow-wave structures based on microstrip lines loaded with patch capacitors. Thanks to the presence of the shunt capacitors, the effective capacitance of the line is enhanced, and the phase velocity of the structure can be made significantly smaller than the one of the unloaded line. The target is to achieve the layout of the slow-wave structure able to provide the required slow-wave ratio, characteristic Bloch impedance and electrical length i.e., the usual specifications in the design of slow-wave transmission lines. To this end, a two-step synthesis method, based on the aggressive space mapping ASM algorithm, is proposed for the first time. Through the first ASM algorithm, the circuit schematic providing the target specifications is determined. Then, the second ASM optimizer is used to generate the layout of the structure. To illustrate the potential of the proposed synthesis method, three application examples are successfully reported. The two-step ASM algorithm is able to provide the layout of the considered structures from the required specifications, without the need of an external aid in the process. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:629-638, 2015.

Design of Planar Wideband Bandpass Filters From Specifications Using a Two-Step Aggressive Space Mapping (ASM) Optimization Algorithm

This paper is focused on the automated and unattended optimization of a type of planar wideband bandpass filters by means of aggressive space mapping (ASM). The considered filters are microstrip filters implemented through a combination of shunt connected stepped impedance resonators (SIRs) and grounded stubs coupled through admittance inverters. The most relevant and novel aspect of this paper is the fact that the filter layout is automatically generated from filter specifications, i.e., central frequency, fractional bandwidth, in-band ripple and order, without the need of any external aid to the design process. To achieve this layout generation, filter optimization has been divided into two independent ASM processes. The first one generates the filter schematic (circuit element values) providing the required specifications. This first iterative process is necessary since, due to the narrow band operation of the admittance inverters, the target specifications are achieved by compensating the effects of such narrow band operation. The purpose of the second ASM algorithm is to automatically generate the layout from the filter schematic resulting from the first ASM process. To validate the new two-step ASM optimization tool, two sets of filter specifications (inputs of the developed tool), are considered. The generated filter layouts exhibit frequency responses that satisfy the specifications, and are in excellent agreement with the responses of the schematics.

Space-mapping in fluid–structure interaction problems

Transient response due to gust loads can lead to structural failure despite the fact that the aero-elastic system is asymptotically stable. Unsteady aeroelastic analysis should therefore be included in the load calculation cycle of the aircraft design process. Especially in the transonic regime, partitioned strong coupling algorithms perform better than loose coupling algorithms and allow larger time-steps in the unsteady simulation. However, the simulation of high fidelity unsteady fluid–structure interaction using strong coupling algorithms is currently too expensive in order to be useful in industry.To accelerate high fidelity partitioned fluid–structure interaction simulations we apply space-mapping, which is a technique that originates from the field of multi-fidelity optimization. Without loss of generality we assume the availability of a cheap low fidelity fluid solver and an expensive high fidelity fluid solver. The space-mapping approach is used to accelerate the high fidelity computation using black-box input/output information of both the high fidelity fluid solver and low fidelity fluid solver. In order to achieve this, a space-mapping function is defined on the fluid–structure interface which keeps track of the differences between the high fidelity model and the low fidelity model during the coupling iterations. Reformulating the root-finding problem on the fluid–structure interaction interface using the space-mapping function results in the Aggressive Space-Mapping algorithm.The Aggressive Space-Mapping algorithm is applied to 1-D and 2-D test cases in order to assess the speedup with respect to the Quasi-Newton Inverse Least Squares algorithm. The latter is considered to be the current state of the art in partitioned strong coupling algorithms. The observed speedup depends mainly on the type of FSI problem and the time step size. The maximum observed speedup is about 1.5.The application of the space-mapping technique to partitioned fluid–structure interaction problems is found to be a promising approach. The framework is non-intrusive and allows the reuse of existing solvers which is especially useful in an industrial environment. It is expected that the space-mapping technique can be combined with higher order time integration schemes that maintain accuracy over a large range of time step sizes.

Space mapping-focused control techniques for particle dispersions in fluids

We present and investigate techniques for optimizing particle dispersions in all kinds of Reynolds number flows. In particular, we show the range of application, power and efficiency of space mapping approaches that are based on a hierarchy of models ranging from a complex (fine, accurate, costly) to simple (coarse, rough, cheap) model. Space mapping turns out to be a reasonable approximation to optimal control and a competitive alternative to instantaneous control regarding speed and memory demands when dealing with complex, non-stationary problems. Moreover it allows the easy and efficient treatment of stochastic design problems. To control random particle dynamics in a turbulent flow, we suggest a Monte-Carlo aggressive space mapping algorithm which yields very convincing numerical results.

OPTIMAL DOPANT PROFILING BASED ON ENERGY-TRANSPORT SEMICONDUCTOR MODELS

We consider optimal design problems for semiconductor devices which are simulated using the energy transport model. We develop a descent algorithm based on the adjoint calculus and present numerical results for a ballistic diode. Furthermore, we compare the optimal doping profile with results computed based on the drift diffusion model. Finally, we exploit the model hierarchy and test the space mapping approach, especially the aggressive space mapping algorithm, for the design problem. This yields a significant reduction of numerical costs and programming effort.

A hybrid aggressive space-mapping algorithm for EM optimization

We propose a novel hybrid aggressive space-mapping (HASM) optimization algorithm. HASM exploits both the trust-region aggressive space-mapping (TRASM) strategy and direct optimization. Severe differences between the coarse and fine models and nonuniqueness of the parameter extraction procedure may cause the TRASM algorithm to be trapped in local minima. The HASM algorithm is based on a novel lemma that enables smooth switching from the TRASM optimization to direct optimization if the TRASM algorithm is not converging. It also enables switching back from direct optimization to the TRASM algorithm in a smooth way. The uniqueness of the extraction step is improved by utilizing a good starting point. The algorithm does not assume that the final space-mapped design is the true optimal design and is robust against severe misalignment between the coarse and fine models. The examples include a seven-section waveguide transformer, the design of a H-plane waveguide filter, and a double-folded stub filter.

A trust region aggressive space mapping algorithm for EM optimization

A robust new algorithm for electromagnetic (EM) optimization of microwave circuits is presented. The algorithm (TRASM) integrates a trust region methodology with the aggressive space mapping (ASM). The trust region ensures that each iteration results in improved alignment between the coarse and fine models needed to execute ASM. The parameter extraction step is a crucial part of the ASM technique. The nonuniqueness of this step may result in the divergence of the technique. To improve the uniqueness of the extraction phase, we developed a recursive multipoint parameter extraction. This suggested step exploits all the available EM simulations for improving the uniqueness of parameter extraction. The new algorithm was successfully used to design a number of microwave circuits. Examples include the EM optimization of a double-folded stub filter and of a high-temperature superconducting (HTS) filter using Sonnet's em. The proposed algorithm was also used to design two-section, three-section, and seven-section waveguide transformers exploiting Maxwell Eminence. The design of a three-section waveguide transformer with rounded corners was carried out using HP HFSS. We show how the mapping can be used to carry out Monte Carlo analysis using only coarse model simulations.