Elliptic Low-pass Filter Research Articles

Perturbation Effect on IIR Filters

During the realization of digital FIR and IIR filters the finite word length in computers affects the accuracy of filter coefficients. This leads to change in actual desired poles and zeros of the system function. In this paper firstly the analog filter is converted to digital domain using bilinear transformation and then the filter coefficients are quantized to analyze the perturbation error and the finite word length effect.This paper analyzes the sensitivity to quantization of filter coefficients for 8-bit, 16-bit and 32-bit precisions up to order 7 for digital low pass Butterworth, Chebyshev (type I and type II) and Elliptic filters for direct form realization. In the end result shows that the Chebyshev type II filter yields the least perturbation error and Elliptic filter yields the maximum perturbation error for higher orders.

Planar elliptic function lowpass filter with sharp roll-off and wide stopband

A compact planar elliptic function lowpass filter with sharp roll-off at 20 dB attenuation level and wide stopband using microstrip stepped-impedance polygonal patch resonators is developed and investigated. Electromagnetic simulation is used to optimize the performance of the filter. The filter using cascaded multiple patch resonators provides a very sharp attenuation near cutoff frequency with a high stopband suppression level. The rejection bandwidth is enhanced by introducing additional transmission zeroes and the results are validated by the experiment. The filter has a compact size of 17.6 mm × 12.2 mm. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:133–136, 2016

MICROSTRIP LOW PASS FILTER DESIGNS USING DEFECTED GROUND STRUCTURE

The microwave filters play an important role in most RF/microwave applications. They are designed to remove undesired harmonics to reduce the system noise or to remove spurious mixing products. DGS slot with an interdigital shape are introduced here in two elliptic low pass filter designs. Here a fifth order low pass filter was designed, simulated and fabricated for a cut off frequency of 3GHz. Finally a prototype model were designed based on the simulation results obtained. These prototype filter designs have more than 20 dB of stop band rejection and a good return loss in the pass band. The fabricated results proved to be better than the simulation results. In the first low pas filter design the central aperture was replaced with the interdigital slot structure which improved the stop band response at the resonant frequency around 7.8 GHz. To improve the stop band rejection two interdigital structures were introduced in the bottom layer (Ground).

A systematic implementation of elliptic low-pass filters using defected ground structures

For the past decade, defected ground structures (DGSs) are largely used in the implementation of low-pass filters, without a systematic approach. In this paper, a simple systematic approach for the design of elliptic low-pass filters using DGSs is proposed. An empirical model for a simple rectangular slot DGS is extracted for its equivalent circuit. Using this model, low-pass filters for various orders are designed for critical filter specifications and optimized by reducing the parasitic effects induced by DGSs. This systematic implementation of DGS-based filters achieves more than 90% of the desired filter specifications. Due to the improved slow-wave factor and power handling capacity of DGSs, the filter is more compact and reliable than the conventional filters.

Voltage-Mode CFTA-C Third-Order Elliptic Low-Pass Filter Design and Optimization Using Signal Flow Graph Approach

In this work, two active only grounded-C equivalents of third-order voltage-mode (VM) elliptic low-pass (LP) LC ladder prototype are proposed. As active building blocks (ABBs) the recently introduced current follower transconductance amplifier (CFTA) were used. The first active only grounded-C LP filter employing eight CFTAs was proposed by interconnecting CFTA-based active equivalent sub-blocks of passive components, where one of the low-impedance input terminals is not used. Since such feature may cause some noise injection into the proposed circuit, the proposed filter was optimized using Mason-Coates' signal flow graph approach. In several steps the number of ABBs was reduced by two and the unused input terminal was eliminated. The performance of the novel and optimized active only grounded-C third-order VM elliptic LP filter was tested experimentally using the readily available UCC-N1B integrated circuit. DOI: http://dx.doi.org/10.5755/j01.eee.21.2.11508

An Underfrequency Load Shedding Scheme with Minimal Knowledge of System Parameters

Abstract Underfrequency load shedding (UFLS) is a common practice to protect a power system during large generation deficit. The adaptive UFLS schemes proposed in the literature have the drawbacks such as requirement of transmission of local frequency measurements to a central location and knowledge of system parameters, such as inertia constant H and load damping constant D. In this paper, a UFLS scheme that uses only the local frequency measurements is proposed. The proposed method does not require prior knowledge of H and D. The scheme is developed for power systems with and without spinning reserve. The proposed scheme requires frequency measurements free from the oscillations at the swing mode frequencies. Use of an elliptic low pass filter to remove these oscillations is proposed. The scheme is tested on a 2 generator system and the 10 generator New England system. Performance of the scheme with power system stabilizer is also studied.

Design and Implementation of Butterworth, Chebyshev-I and Elliptic Filter for Speech Signal Analysis

In the field of digital signal processing, the function of a filter is to remove unwanted parts of the signal such as random noise that is also undesirable. To remove noise from the speech signal transmission or to extract useful parts of the signal such as the components lying within a certain frequency range, filters are necessary. Filters are broadly used in signal processing and communication systems in applications such as channel equalization, noise reduction, radar, audio processing, speech signal processing, video processing, biomedical signal processing that is noisy ECG, EEG, EMG signal filtering, electrical circuit analysis and analysis of economic and financial data. In this paper, three types of infinite impulse response filter i.e. Butterworth, Chebyshev type I and Elliptical filter have been discussed theoretically and experimentally. Butterworth, Chebyshev type I and elliptic low pass, high pass, band pass and band stop filter have been designed in this paper using MATLAB Software. The impulse responses, magnitude responses, phase responses of Butterworth, Chebyshev type I and Elliptical filter for filtering the speech signal have been observed in this paper. Analyzing the Speech signal, its sampling rate and spectrum response have also been found.

Fuzzy Adaptive Modified PSO Algorithm Assisted to Design of Six Order Elliptic Low Pass Filter

To provide cost-effective communication systems for separate a signal into different frequency region and eliminate adverse signals and harmonics, Fuzzy Adaptive Modified particle swarm optimization (FAMPSO) method was used to have an optimized gain ripple of 6 th order elliptic low pass filter with 300 MHz cut-off frequency. The feasibility and effectiveness of the FAMPSO algorithm is demonstrated and results are compared with PSO algorithm. It is shown that FAMPSO has high quality solution, superior convergence characteristics and shorter computation time.

A Survey on the Design of Lowpass Elliptic Filters

The objective of this review paper, is the presentation of the basic features of the well known class of elliptic filters. Even though this is not a new subject, the theory of the elliptic filters found in most books is restricted only to a few resulting equations, due to the great complexity associated with the Jacobian elliptic functions. The aspects of the elliptic filters described in this paper include the detailed estimation of the minimum filter order, the construction of the filter transfer function via the identification of its poles and zeros in the complex plane, as well as the application of the resulting design procedure for the construction of an elliptic filter that meets prescribed specifications.

High-Order Active Filter Design Based on Component-Level Signal Flow Graph Method

In this paper, a seventh-order elliptic low-pass active-RC filter with three finite transmission zeros is designed for the baseband filter of a 433MHz wireless communication terminal. While designing, the canonical signal flow graph (SFG) method is applied based on component-level simulation of LC ladder prototype circuit. The simulation and measurement results show that the filter satisfied the design specifications.

Study on Elliptic Filters in Airborne Gravity Data Processing

For low-pass filtering of airborne gravity data processing, elliptic low-pass digital filters were designed and filtering influences of the elliptic filter order, upper limit passband frequency, maximal passband attenuation and minimal stopband attenuation were studied. The results show that the upper limit passband frequency has the greatest effect on filtering among four parameters; the filter order and the maximal passband attenuation have some influence, but instability will increase with larger order; the effect of the minimal stopband attenuation is not obvious when reaching a certain value, which requires a combination of evaluation indicator accuracy to determine the optimal value. The standard deviations of discrepancies between the elliptic filtered gravity anomaly with optimal parameters and the commercial software result are within 1mGal, and the internal accord accuracy along four survey lines after level adjusting is about 0.620mGal.

Ultra-wide stopband low-pass filter using symmetrical cascaded modified hairpin resonators

An elliptical function low-pass filter LPF with ultra wide stopband and sharp cutoff frequency is proposed. This filter is composed of symmetrical cascaded modified hairpin resonators and U-shaped resonators. The transition band is from 1 to 1.21 GHz with -3 and -20 dB, respectively. For this filter, the return loss is better than 17 dB in 80% of passband width, where the insertion loss is less than 0.3 dB. The band-stop rejection is greater than 20 dB from 1.21 to 26.35 GHz and 40 dB from 1.35 to 12.5 GHz. To validate the design and analysis, the proposed LPF has been designed and fabricated on a 20 mil thick RO4003 substrate with a relative dielectric constant 3.38 and loss tangent of 0.0021. The filter is evaluated by experiment and simulation with a good agreement. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:314-321, 2014.

Design and Simulation of Switched Capacitor Filter for Speed Change Parameter Converter

In this paper, we design a high-order switched capacitor filter for rapid change parameter converter. This design uses a structure which consists of three biquads filter sub-units. The design is a 6th-order SC elliptic low-pass filter, and the sample frequency is 250 kHz. By the MATLAB Simulink simulation, the system can meet the design requirements in the time domain. In this paper, the 6th-order switched capacitor elliptic low-pass filter was implemented under 0.5 um CMOS process and simulated in Cadence. The final simulation results show that the pass-band cutoff frequency is 10 kHz, and the maximum pass-band ripple is about 0.106 dB. The stop-band cutoff frequency is 20 kHz, and the minimum stop-band attenuation is 74.78 dB.

Design of coplanar-waveguide-based elliptic filter using T-shaped defected ground structure

In this paper T-shaped Defected Ground Structure (DGS) has been proposed in the ground plane of the conventional coplanar-waveguide (CPW) structure. The T-shaped DGS has wider gap capacitance than the conventional dumbbell-shaped DGS, and provides a wide stop band and slow-wave characteristics. Thus, utilizing the above properties array of two T-shaped DGS structures has been introduced to obtain an elliptic low-pass filter (LPF). This proposed LPF is suitable for transferring low frequency signal up to 2.5 GHz satisfactorily. It provides sharp transition between pass- and stop-band with good sharpness factor, but almost 1.2 dB insertion loss in the pass-band. Therefore, the insertion loss in the pass-band is reduced with the help of compensated Hi–Lo coplanar waveguide (CPW) transmission line.

칩 인덕터를 사용하여 광대역 저지 특성을 갖는 소형 C-밴드 Semi-Lumped 저역 통과 여파기

칩 인덕터를 이용하여 넓은 저지 대역과 소형화 특성을 갖는 C-밴드 semi-lumped 저역 통과 여파기를 제안하였다. 칩 인덕터의 자기 공진 주파수(SRF: Self Resonance Frequency) 특성을 유지하기 위하여 추가된 분리형 인덕터와 SRF 특성으로 인해 발생되는 감쇠 폴을 이용하여 광대역 저지 대역과 높은 저지 특성을 얻을 수 있었다. 3차 elliptic function 여파기에 칩 인덕터(L: 9.1 nH, SRF: 5.5 GHz, Q: 25)를 적용한 결과, 마이크로스트립 라인 인덕터로 구현한 여파기보다 크기가 37.4 % 감소하였으며, 삽입 손실이 0.38 dB, 차단 주파수는 920 MHz, 1.43~7.8 GHz의 넓은 저지 대역(20 dB 이하) 특성을 가졌다. The C-band semi-lumped lowpass filter with broad stopband and compact size characteristic using chip inductor is proposed. To provide an additional attenuation pole in stopband by SRF, a separable inductor is added to proposed structure, and it has broad stopband characteristic. The third order elliptic function lowpass filter with chip inductor(L: 9.1 nH, SRF: 5.5 GHz, Q: 25) has insertion loss of 0.38 dB, cutoff frequency of 920 MHz, broad stopband(below 20 dB) of 1.43~7.8 GHz and the size is reduced 37.4 % compared to distributed inductor.

Modeling and Validation of Coplanar Waveguide Elliptic Filter Using Square Open Complementary Split-Ring Resonator

In this article, an elliptic low-pass filter is implemented in coplanar waveguide technology by etching an open complementary split-ring resonator and one open split-ring slot in the central transmission strip. The structures behave as series-connected parallel resonant tanks, whereas metallic patches etched in the back side of the substrate provide the required shunt capacitances to achieve the elliptic function response. An order-5 elliptic low-pass filter has been designed to illustrate the possibilities of this new approach. Since the open complementary split-ring resonator is an electrically small resonator and the dimension of the open split-ring slot is also very small, the designed filter dimensions are also small compared to the filters designed by split-ring resonators, complementary split-ring resonators, or other procedures.

CMOS analog baseband circuitry for an IEEE 802.11 b/g/n WLAN transceiver

An analog baseband circuit for a direct conversion wireless local area network (WLAN) transceiver in a standard 0.13-μm CMOS occupying 1.26 mm2 is presented. The circuit consists of active-RC receiver (RX) 4th order elliptic lowpass filters(LPFs), transmit (PGAs) with DC offset cancellation (DCOC) servo loops, and on-chip output buffers. The RX baseband gain can be programmed in the range of −11 to 49 dB in 2 dB steps with 50–30.2 nV/√Hz input referred noise (IRN) and a 21 to −41 dBm in-band 3rd order interception point (IIP3). The RX/TX LPF cutoff frequencies can be switched between 5 MHz, 10 MHz, and 20 MHz to fulfill the multimode 802.11b/g/n requirements. The TX baseband gain of the I/Q paths are tuned separately from −1.6 to 0.9 dB in 0.1 dB steps to calibrate TX I/Q gain mismatches. By using an identical integrator based elliptic filter synthesis method together with global compensation applied to the LPF capacitor array, the power consumption of the RX LPF is considerably reduced and the proposed chip draws 26.8 mA/8 mA by the RX/TX baseband paths from a 1.2 V supply.

Noise-immunity of the double-loop system of automatic control

Dynamic transients in a double-loop system of automatic control are under investigations exemplified #by the double-loop frequency-phase system of automatic frequency control. An algorithm of noise-immunity determination of such a system is described. As an example, the pulse and transient characteristics of the double-loop frequency-phase system of automatic frequency control are calculated. The system contains a third-order elliptic low-pass filter, which allows increasing of the system’s noise immunity. Results are obtained both with the help of direct solution of the nonlinear differential equation of the dynamic system in the Mathcad environment and using simulation in the Matlab Simulink environment.

Design Elliptic Lowpass Filter with Inductively Compensated Parallel-Coupled Lines

This paper presents a simple technique to design an ellicptic transfer fuction microstrip lowpass filter based on a ection of doubly inductive compensated parallel-coupled lines. The proposed lowpass filter has the suppression performance to suppress the signal transmission in transition and stopband better than the filter based on the conventional coupled lines. The proposed design procedures are convenient with the closed form design equation. To emonstrate the techniques performance, simulated and measured results at 0.9GHz cut off frequency LPF with ncompensated and the compensated structures are compared. The measured results obtained from the proposed LPF exhibit 0.2dB insertions, less than 20dB return loss and more suppression performance than 35dB at 1.8GHz.

A low power 8th order elliptic low-pass filter for a CMMB tuner

This paper presents an 8th order active-RC elliptic low-pass filter (LPF) for a direct conversion China Mobile Multimedia Broadcasting (CMMB) tuner with a 1 or 4 MHz −3 dB cutoff frequency (f−3dB). By using a novel gain-bandwidth-product (GBW) extension technique in designing the operational amplifiers (op-amps), the proposed filter achieves 71 dB stop-band rejection at 1.7 f−3dB to meet the stringent CMMB adjacent channel rejection (ACR) specifications while dissipates only 2.8 mA/channel from a 3 V supply, its bias current can be further lowered to 2 mA/channel with only 0.5 dB peaking measured at the filter's pass-band edge. Elaborated common-mode (CM) control circuits are applied to the filter op-amp to increase its common-mode rejection ratio (CMRR) and effectively reject the large signal common-mode interference. Measurement results show that the filter has 128 dBμVrms in-band IIP3 and more than 80 dB passband CMRR. Fabricated in a 0.35-μm SiGe BiCMOS process, the proposed filter occupies a 1.19 mm2 die area.