Showing papers on "Filter design published in 2022"
TL;DR: In this article , a linear prefilter was introduced to whiten the correlated noise (i.e., colored noise) for obtaining the unbiased estimate of the filter weight, and a new gradient approach was developed for the adaptive filter design based on the fractional-order derivative and a linear filter.
Abstract: The previous work for the filter design considers uncorrelated white measurement noise disturbance. For more complex correlated noise disturbance, the conventional adaptive filter results in biased estimates. To overcome this problem, we introduce a linear prefilter to whiten the correlated noise (i.e., colored noise) for obtaining the unbiased estimate of the filter weight. Moreover, the design of some adaptive filters mainly focuses on the integer-order optimization methods. However, compared with the integer-order-based adaptive algorithms, the fractional-order-based algorithms show better performance. Thus, this letter develops a new gradient approach for the adaptive filter design based on the fractional-order derivative and a linear filter. Finally, the simulation results are provided from the system identification perspective for demonstrating the performance analysis of the proposed algorithms.
93 citations
TL;DR: In this paper , a Takagi-Sugeno fuzzy model is constructed to represent the nonlinear plant and a fuzzy filter design for the singular system is proposed, such that the formulated filtering error system is admissible (regular, impulse-free, and stable) and ensures the corresponding filtering performance.
Abstract: This article studies the energy-to-peak filter design problem for the continuous-time nonlinear singular system. A Takagi–Sugeno fuzzy model is constructed to represent the nonlinear plant. The article focuses on the fuzzy filter design for singular system, such that the formulated filtering error system is admissible (regular, impulse-free, and stable) and ensures the corresponding filtering performance in the singular system. By introducing a novel Lyapunov function, design conditions of the fuzzy filter for the continuous-time singular system are proposed in the light of linear matrix inequalities representations. Finally, a practical example and the relevant simulation results are provided to demonstrate the effectiveness and feasibility of the proposed energy-to-peak filter design approach.
26 citations
TL;DR: In this article , a matrix inequality decoupling approach is proposed to separate the product terms with different types of uncertainties, and the resulting design condition of the resilient filter is described by strict linear matrix inequalities.
Abstract: In this article, the resilient $\mathcal H_\infty$ $\mathcal H_\infty$
23 citations
TL;DR: In this paper, the authors present a systematic as well as unified approach to design the EMI filter for any power electronic converter, particularly for three-phase ac-dc active boost rectifier systems.
Abstract: Designing an efficient, compact, and optimized electromagnetic interference (EMI) filter for the next generation high-frequency switched mode power converter while maintaining a small form factor with high power density, requires adequate research and development effort. This article presents a systematic as well as unified approach to design the EMI filter for any power electronic converter, particularly for three-phase ac–dc active boost rectifier systems. Since the differential mode (DM) filter stage consumes a major part of the EMI filter volume and weight, DM filter design optimization is a necessary yet challenging task to attain a higher power density. This article theoretically demonstrates the design steps for choosing the appropriate filter component values and number of filter stages to achieve the smallest volume of the DM EMI filter. Furthermore, to design an optimized common mode (CM) filter stage, a research effort has been made for estimation of the CM noise corner frequencies followed by multiconstraint volume optimization through a detailed mathematical noise modeling of the converter. While the validation of the proposed design methodology is done through MATLAB simulation, an experimental verification is also performed by designing the optimized EMI filter for a 2.3-kW proof of concept of a three-phase boost power factor correction converter to comply with the stringent EMI requirements of DO-160F standard.
13 citations
TL;DR: In this paper , the anti-ISRJ methods are studied in order to suppress the interrupted-sampling repeater jamming based on the waveform and filter design for SAR.
Abstract: The interrupted-sampling repeater jamming (ISRJ) is coherent and has the characteristic of suppression and deception to degrade the synthetic aperture radar (SAR) image quality. The anti-ISRJ methods are studied in this work in order to suppress the ISRJ based on the waveform and filter design for SAR. First, the relationship between the ISRJ and waveform is obtained by analyzing the principle of the ISRJ using the ambiguity function. The ISRJ produces multiple false targets based on the high Doppler tolerance of waveform and the characteristic of the matched filter. Next, a method is proposed to counter the ISRJ by transmitting a phase-coded (PC) waveform with low Doppler tolerance and designing the corresponding mismatched filter. The joint design method is then developed to improve the anti-ISRJ and imaging performance. In the proposed methods, the majorization minimization framework is introduced to solve the nonconvex waveform and filter design problem. Finally, several simulations are conducted to demonstrate the effectiveness of the proposed methods. Simulation results show that the joint design method shows better anti-ISRJ and imaging performance in comparison with the separate design method, but it is more sensitive to the ISRJ sampling duty ratio and period.
12 citations
10 citations
TL;DR: A new approach to designing the Frobenius norm-based weighted unbiased finite impulse response (FIR) fusion filter for wireless sensor networks and it is demonstrated to have higher robustness against uncertainties than Kalman filter-based methods.
Abstract: This article presents a new approach to designing the Frobenius norm-based weighted unbiased finite impulse response (FIR) fusion filter for wireless sensor networks. The weighted Frobenius norm is employed as a cost function to design a local unbiased FIR filter. The design problem is converted into a constrained optimization problem subject to an equality constraint. The Lagrange multiplier method is used to derive the local FIR filter gain. An alternative Frobenius norm is introduced to determine weights for the local unbiased FIR filters in the design of a global fusion FIR filter. The developed FIR fusion filter is demonstrated to have higher robustness against uncertainties than Kalman filter-based methods, such as the optimal fusion Kalman filter, distributed Kalman filter, and distributed weighted Kalman filter, through a numerical example of moving-target tracking employing seven smart sensors and an experiment with temperature and humidity estimation using eight sensors.
10 citations
TL;DR: In this article , a first-of-a-kind mixed-mode universal filter employing three VDBAs and three passive components, is proposed, which operates in all four modes and provides all five filter responses.
Abstract: In this paper, a first-of-a-kind mixed-mode universal filter employing three VDBAs and three passive components, is proposed. The filter operates in all four modes and provides all five filter responses, namely voltage-mode (VM), current-mode (CM), trans-impedance-mode (TIM), or trans-admittance-mode (TAM). Additionally, the same filter topology can also work as a CM single-input-multi-output (SIMO) filter. A state-of-the-art comparison of various ‘voltage differencing’ variants of the voltage differencing buffered amplifier (VDBA)-based SIMO/MISO (single-input-multi-output/multi-input-single-output)-type biquad filters further highlight the significance of the presented research. In the proposed no passive component matching is required for generating the filter responses. The filter circuit also provides inbuilt tunability of the quality factor independent of the pole frequency. The non-ideal frequency dependent gain and component sensitivity analyses of the filter were also performed. The Silterra Malaysia 0.18μm process design kit (PDK) is employed to design and validated the proposed VDBA-based filter using the Cadence design software. The simulation results closely follow the theoretical predictions. To further verify the practical feasibility of the proposed filter, an experimental evaluation is also completed. The VDBA-based filter is implemented using off-the-shelf operational transconductance amplifiers Intersil CA3080, Texas Instruments LF356 op-amp, and Analog Devices AD844s. The filter is designed for a characteristic frequency of 100 kHz. The time and frequency domain measurement results indicate the proper functioning of the filter.
10 citations
TL;DR: In this paper , the fault detection filter design problem is addressed for discrete-time memristive neural networks with time delays. And an augmented Lyapunov functional is constructed by utilizing the summation inequality approach and the improved reciprocally convex combination method, an FD filter that guarantees the asymptotic stability and the prescribed H∞ performance level of the residual system is designed.
Abstract: In this article, the fault detection (FD) filter design problem is addressed for discrete-time memristive neural networks with time delays. When constructing the system model, an event-triggered communication mechanism is investigated to reduce the communication burden and a fault weighting matrix function is adopted to improve the accuracy of the FD filter. Then, based on the Lyapunov functional theory, an augmented Lyapunov functional is constructed. By utilizing the summation inequality approach and the improved reciprocally convex combination method, an FD filter that guarantees the asymptotic stability and the prescribed H∞ performance level of the residual system is designed. Finally, numerical simulations are provided to illustrate the effectiveness of the presented results.
9 citations
TL;DR: In this paper , a design methodology for minimum volume of LCL filters applied to grid connected converters is proposed, which combines the determination of filter parameter values (inductances and capacitances) to hardware design (component technology and inductor construction).
Abstract: A design methodology for minimum volume of LCL filters applied to grid connected converters is proposed. It combines the determination of filter parameter values (inductances and capacitances) to hardware design (component technology and inductor construction). Using the proposed strategy, different combinations of L-C-L that meet standard restrictions are determined. The influence of the harmonic content that results from filter design is considered in order to estimate component losses, and filter and bus capacitor lifetimes. Results are presented for filters that lead to the smallest volume, highest capacitor lifetime, or a compromise between both. A case study with three different magnetic material technologies and two types of capacitors is done. The design methodology is experimentally validated for a 1 kW converter. Step-by-step procedures for the determination of filter parameters and inductor hardware design are provided.
9 citations
TL;DR: In this paper , the authors present a systematic as well as unified approach to design the EMI filter for any power electronic converter, particularly for three-phase ac-dc active boost rectifier systems.
Abstract: Designing an efficient, compact, and optimized electromagnetic interference (EMI) filter for the next generation high-frequency switched mode power converter while maintaining a small form factor with high power density, requires adequate research and development effort. This article presents a systematic as well as unified approach to design the EMI filter for any power electronic converter, particularly for three-phase ac–dc active boost rectifier systems. Since the differential mode (DM) filter stage consumes a major part of the EMI filter volume and weight, DM filter design optimization is a necessary yet challenging task to attain a higher power density. This article theoretically demonstrates the design steps for choosing the appropriate filter component values and number of filter stages to achieve the smallest volume of the DM EMI filter. Furthermore, to design an optimized common mode (CM) filter stage, a research effort has been made for estimation of the CM noise corner frequencies followed by multiconstraint volume optimization through a detailed mathematical noise modeling of the converter. While the validation of the proposed design methodology is done through MATLAB simulation, an experimental verification is also performed by designing the optimized EMI filter for a 2.3-kW proof of concept of a three-phase boost power factor correction converter to comply with the stringent EMI requirements of DO-160F standard.
TL;DR: In this paper , a complete method to design transmission-line reflectionless filters is presented, which can be applied to reflectionless filter prototypes consisting of filtering and matching sections that comply the Cauer topology.
Abstract: This article is to present a complete method to design transmission-line reflectionless filters. Our approach can be used to accord a transmission-line filter to feature an infinite frequency range of reflectionless response. It can be applied to reflectionless filter prototypes consisting of filtering and matching sections that comply the Cauer topology. Hence, it does not limit by the filter order and/or the filter response type. Design equations supporting our approach are provided, and their applications to actual filter designs will be elaborated via various filter examples with distinct features. The measurements authenticate our design approach.
TL;DR: This work presents a natively fixed-point filter design method that targets FPGA-based Reconfigurable Finite Impulse Response (RFIR) filters for Software Defined Radio applications, and finds that the method is up to three orders of magnitude faster than an equivalent software implementation.
Abstract: We present a natively fixed-point filter design method that targets FPGA-based Reconfigurable Finite Impulse Response (RFIR) filters for Software Defined Radio applications. The Filter Designer is capable of reconfiguring cut-off frequencies on-the-fly at run-time; with other parameters, such as filter length and window type, configurable at compile-time. The ability to compute filter coefficients directly on FPGAs is compelling, as much lower latencies can be achieved when compared to RFIRs programmed with embedded processors. In this work we discuss several filter design techniques from the literature and investigate their suitability for implementation on FPGAs. A hybrid method combining window and frequency sampling methods is developed and implemented on a Xilinx Zynq-7000 SoC. We explore the limitations of designing filters in fixed-point arithmetic and consider the effects filter length and wordlength have on filter quality. Results show that the proposed algorithm generates good-quality filters that display stopband attenuation up to 88dB, transition bandwidths less than 1% of the sample rate, and low resource utilisation. Most notably, we found that our method is up to three orders of magnitude faster than an equivalent software implementation, with execution times as low as 2.52 $\mu \text{s}$ , enabling radio applications in which latency is a principal constraint.
TL;DR: In this paper , the authors proposed a modularized design approach of a completely reconfigurable non-uniform filter bank for hearing aid systems, which consists of a multiband generation module and a subband extraction module.
Abstract: Filter banks with good reconfigurability are desired in hearing aid systems due to the individual requirements of patients with different hearing loss characteristics. This paper proposes a modularized design approach of a completely reconfigurable nonuniform filter bank for hearing aid systems. The proposed filter bank structure consists of a multiband generation module and a subband extraction module, where the frequency warping technique is adopted. Based on theoretical analyses of second order frequency warping, the subband distribution can be flexibly controlled. Moreover, to adapt the subband extraction module design to the multiband generation module, the relationship between control parameters is analyzed and a mapping formula is derived. Through the co-design of the two modules, superior reconfigurability over existing methods is achieved. Application examples show that the proposed filter bank is able to provide multiple subbands distribution schemes that satisfy the requirements of different audiograms. The proposed filter bank structure has lower complexity, smaller delay and smaller matching errors than existing filter bank structures due to its flexible structure.
TL;DR: In this article , the authors proposed an optimum design approach for fractional-order Chebyshev low-pass filters that meet design specifications based on genetic algorithm (GA), where the fractional order and ripples attenuation were calculated according to specifications.
Abstract: Fractional‐order filters have received extensive attention from international scholars because of their greater design freedom and continuously stepped stopband attenuation rate. Based on genetic algorithm (GA), this paper proposes an optimum design approach for fractional‐order Chebyshev lowpass filters that meet design specifications. The fractional order and ripples attenuation of the normalized Chebyshev lowpass filter are calculated according to specifications, the integer order in the Chebyshev polynomial is replaced with the calculated fractional order, and then the fractional‐order Chebyshev polynomial is substituted into the magnitude response of the normalized Chebyshev lowpass filter along with the ripples attenuation to achieve the ideal response. The transfer function parameters of a fractional‐order filter are optimized using GA to make the magnitude response approximate the ideal response described above. This completes the optimized design of a fractional‐order Chebyshev filter that meets specifications. Given three different sets of design specifications, the fractional‐order Chebyshev filter designed using the proposed method is compared with one designed by another method in the literature. Finally, design examples are presented, stability analysis and Pspice simulations are performed, and an actual circuit is constructed to illustrate the effectiveness of the proposed method.
TL;DR: In this paper , a mixed-mode first-order universal filter configuration is presented that employs three operational transconductance amplifiers (OTAs) and one grounded capacitor (eminently suitable for IC chip fabrication).
Abstract: In this paper, a new mixed-mode first-order universal filter configuration is presented that employs three operational transconductance amplifiers (OTAs) and one grounded capacitor (eminently suitable for IC chip fabrication). All three first-order generic filter functions, namely low pass filter (LPF), high pass filter (HPF) and all pass filter (APF) in all the four possible modes, namely voltage mode (VM), current mode (CM), transresistance mode (TRM) and transconductance mode (TCM) can be realized. The proposed configuration offers high input impedance and high output impedance. The pole frequency of the filter can be controlled electronically by varying a single transconductance. Nonideal analysis of the proposed filter structure has also been carried out and the results have been compared with those obtained from ideal analysis. The performance of the presented filter configuration has been corroborated through PSPICE simulations as well as experimental results. The various simulation and experimental results validate the practical viability of the proposed configurations.
TL;DR: In this paper, a novel approach for solving inverse heat conduction problems in one-dimensional domain with moving boundary and temperature dependent material properties is presented, where two thermocouples are used to measure temperature at two interior locations within the medium while the front boundary experiences recession (moving towards the back surface).
TL;DR: In this article , the Frobenius norm-based weighted unbiased finite impulse response (FIR) fusion filter for wireless sensor networks is proposed, in which the weighted FF is employed as a cost function to design a local unbiased FIR filter and the Lagrange multiplier is used to derive the local FIR filter gain.
Abstract: This article presents a new approach to designing the Frobenius norm-based weighted unbiased finite impulse response (FIR) fusion filter for wireless sensor networks. The weighted Frobenius norm is employed as a cost function to design a local unbiased FIR filter. The design problem is converted into a constrained optimization problem subject to an equality constraint. The Lagrange multiplier method is used to derive the local FIR filter gain. An alternative Frobenius norm is introduced to determine weights for the local unbiased FIR filters in the design of a global fusion FIR filter. The developed FIR fusion filter is demonstrated to have higher robustness against uncertainties than Kalman filter-based methods, such as the optimal fusion Kalman filter, distributed Kalman filter, and distributed weighted Kalman filter, through a numerical example of moving-target tracking employing seven smart sensors and an experiment with temperature and humidity estimation using eight sensors.
TL;DR: In this paper , a decentralized sampled-data H∞ fuzzy filter for nonlinear interconnected systems is proposed, which includes exponential time-varying gains, which leads to enlargement of the sampling period and improvement in the decay rate performance of the filter.
TL;DR: In this paper , a new sampled-data fuzzy filter design method for Takagi-Sugeno fuzzy systems with the asynchronous premise variables is presented, where the membership functions of the filter are affine transformed by scaling and biasing the system's membership functions.
Abstract: This article presents a new sampled-data fuzzy filter design method for Takagi–Sugeno fuzzy systems with the asynchronous premise variables. In the new fuzzy filter design method, the membership functions of the filter are affine transformed by scaling and biasing the system’s membership functions. Taking the advantage of the newly proposed method, the asynchronous problem of the premise variables between the system and filter is easily resolved. Based on the looped function and a modified free-weighting matrix inequality, the sampled system’s output is handled, and the filter design condition is formulated in terms of a parameterized linear matrix inequality with affine matched fuzzy parameter vectors. Additionally, a modified Finsler’s lemma is devised to handle the affine matched fuzzy parameter vectors. By utilizing the relationship between the transformed membership functions, the filter design condition for $H_{\infty }$
TL;DR: This work proposes an algorithm that uses characteristics of a signal to estimate its envelope, eliminating the necessity of parameter tuning, and compares favorably with classic envelope detection techniques based on smoothing, filtering, and the Hilbert transform.
TL;DR: In this article , the authors proposed a power-efficient multichannel low-pass filter for digital image processing based on the cascade multiple accumulate finite impulse response (CMFIR) structure.
Abstract: Abstract The author offers a power-efficient multichannel low-pass filter for digital image processing based on the cascade multiple accumulate finite impulse response (CMFIR) structure in this study. The CMFIR filter was created using the outputs of a linear time-invariant system (LTI), which was built using a cascaded integrator comb (CIC) and a MAC low-pass filter. The sample rate convertor based on CIC filters effectively conducts decimation or interpolation. The sample rate convertor with the CIC filter can only accommodate narrowband transmissions and so cannot be utilized for wideband signals. The MAC architecture-based sample rate convertor is a good solution for high-bandwidth signals, but it uses more resources like registers and flip-flops, which increases power consumption. Here, the CMFIR low-pass filter acts as an interpolator, introducing a sample to boost the image's resolution. CMFIR is a useful tool for addressing the issue of aliasing during sampling. In addition, the genetic algorithm was used to increase the filter's resource utilization and power consumption efficiency.
TL;DR: In this paper , the problem of fault detection for a class of Takagi-Sugeno (T-S) fuzzy semi-Markov jump systems (FSMJSs) with partially unknown transition rates (PUTRs) subject to output quantization was addressed by designing a reduced-order filter.
Abstract: This article deals with the fault detection problem for a class of Takagi–Sugeno (T–S) fuzzy semi-Markov jump systems (FSMJSs) with partly unknown transition rates (PUTRs) subject to output quantization by designing a reduced-order filter. First, a more general PUTRs model is constructed to describe the situation that the information of some elements is completely unknown, where this model is affected simultaneously by PU information and time-varying parameter compared with the traditional PUTRs model. Second, we take full advantage of the reduced-order filter to address the fault detection problem for FSMJSs, in which the stochastic failure phenomenon is injected into the reduced-order filter. Besides, the logarithmic quantizer is employed to tackle the limited bandwidth problem in a communication channel. Consequently, the new sufficient conditions are developed based on the Lyapunov theory to obtain the desired reduced-order filter. Simulation results with respect to the tunnel diode circuit are provided to demonstrate the usefulness and availability of the established theoretical results.
TL;DR: In this paper , the problem of how to select a proper configuration among three types of high-pass filters in a filter package is addressed, which can be used in different applications, ranging from low voltage levels to high voltage levels.
Abstract: In recent years, there is an increased use of passive filters in both transmission and distribution systems due to the proliferation of power electronic devices. However, the problem of filter design has not been well addressed in the past and one example is the application of high-pass filters in a filter package. Three types of HP filters are widely used to mitigate multiple harmonics, i.e., 2 nd HP filter, 3 rd HP filter and C-type filter. There is still a lack of research to clearly reveal the characteristics of each filter, which makes it difficult for the designer to select the optimal filter topology under different circumstances. The main goal of this paper is to solve the problem of how to select a proper configuration among three HP filter candidates for a given harmonic problem. Unlike the conventional optimization-based filter studies, this paper investigates three HP filters in an analytical way. As a result, the paper provides a deep insight into the inherent characteristics of the filter and the conclusions drawn in the paper are universal; thus can be used in different applications, ranging from low voltage levels to high voltage levels. The research results lead to a recommended application scope of each HP filter, which is very useful to guide the design of filter packages and help designers to evaluate the design results.
TL;DR: In this paper , a cascaded integral action-based filter was proposed by relying on the orthogonal output of a delay block, which addresses the problem of initial state when applying a direct integral action to a sinusoidal voltage.
Abstract: This article proposes a cascaded integral action-based filter by relying on the orthogonal output of a $T/4$
TL;DR: In this article , a hybrid Farrow algorithm that combines a modulated Farrow filter with a frequency response interpolated coefficient decimated masking filter is proposed for the design of a novel filter with low computational complexity.
Abstract: Realising a low-complexity Farrow channelisation algorithm for multi-standard receivers in software-defined radio is a challenging task. A Farrow filter operates best at low frequencies while its performance degrades towards the Nyquist region. This makes wideband channelisation in software-defined radio a challenging task with high computational complexity. In this paper, a hybrid Farrow algorithm that combines a modulated Farrow filter with a frequency response interpolated coefficient decimated masking filter is proposed for the design of a novel filter with low computational complexity. A design example shows that the HFarrow filter bank achieved multiplier reduction of 50%, 70% and 64%, respectively, in comparison with non-uniform modulated discrete Fourier transform (NU MDFT FB), coefficient decimated filter bank (CD FB) and interpolated coefficient decimated (ICDM) filter algorithms. The HFarrow filter bank is able to provide the same number of sub-band channels as other algorithms such as non-uniform modulated discrete Fourier transform (NU MDFT FB), coefficient decimated filter bank (CD FB) and interpolated coefficient decimated (ICDM) filter algorithms, but with less computational complexity.
01 Jan 2022
TL;DR: In this article, the authors used MATLAB filter design and analysis tool to preprocess the ECG signal to reduce the baseline drift artifacts in ECG signals, and the performance measures of IIR and FIR filter are analyzed.
Abstract: The electrocardiogram (ECG) is one of the most commonly used technique in the assessment of cardiovascular disease. Cardiovascular disease is one of the major cause of death in many countries so it is important for interpretation of heart beat. The ECG signal during its acquistion gets commonly affected by baseline drift that hinders physician in the correct diagnosis of heart condition. In this work, ECG signal is preprocessed to alleviate noise. Digital filters such as Infinite Impulse Response (IIR) and Finite Impulse Response (FIR) filter are designed for the purpose of removal of artifacts from the signal. The IIR Butterworth low pass filter and least square linear phase low pass FIR filter are designed to reduce the baseline drift artifact in ECG signal. The preprocessing block is designed in MATLAB filter design and analysis tool. The corresponding model is realized in simulink environment. The performance measures of IIR and FIR filter are analyzed. The corresponding HDL code is generated and is targeted to a field programmable gate array board to observe the simulation results.
TL;DR: In this paper , the state-of-the-art microwave filter design methodologies are reviewed, including surrogate modeling (machine learning) methods and advanced optimization algorithms, and three essential techniques in filter designs are included: 1) smart data sampling techniques, 2) advanced surrogate modeling techniques, and 3) advanced optimization methods and frameworks.
Abstract: Microwave filters are indispensable passive devices for modern wireless communication systems. Nowadays, electromagnetic (EM) simulation-based design process is a norm for filter designs. Many EM-based design methodologies for microwave filter design have emerged in recent years to achieve efficiency, automation, and customizability. The majority of EM-based design methods exploit low-cost models (i.e., surrogates) in various forms, and artificial intelligence techniques assist the surrogate modeling and optimization processes. Focusing on surrogate-assisted microwave filter designs, this article first analyzes the characteristic of filter design based on different design objective functions. Then, the state-of-the-art filter design methodologies are reviewed, including surrogate modeling (machine learning) methods and advanced optimization algorithms. Three essential techniques in filter designs are included: 1) smart data sampling techniques; 2) advanced surrogate modeling techniques; and 3) advanced optimization methods and frameworks. To achieve success and stability, they have to be tailored or combined together to achieve the specific characteristics of the microwave filters. Finally, new emerging design applications and future trends in the filter design are discussed.