Composite Lowpass Filter Research Articles

Design of an ultra-sharp composite low-pass filter using analytical method

An ultra-sharp microstrip composite low-pass filter (LPF) with proper structure using analytical method is proposed. A composite LPF using image parameter method and lumped elements is designed is this paper. Then, quasi-lumped elements, such as: open-stub lines, high and low impedance lines and standard microstrip equations are utilized to microstrip implementation. In addition, parasitic substance of the quasi-lumped capacitors are compensated. Moreover, reduce the size of the microstrip filter, the curved microstrip lines are applied. A proposed composite LPF with a cutoff frequency of 1.3 GHz is designed and fabricated. The proposed device has great specifications, such as: ultra-sharp cutoff (600 dB/GHz), compact size (0.100λg × 0.168λg) and high suppression level in stopband (− 35 dB). The measured frequency responses of the proposed LPF, have good agreement with simulation results, which show the validity of the results. With this specifications the proposed filter is suitable for L-band applications.

Composite Lowpass Filter Realized by Image Parameter method and Integrated with Defected Ground Structures

An asymmetric DGS consisting of two square headed slots connected transversely with a rectangular slot is etched in the ground plane underneath a high-low impedance microstrip line. It provides a band-reject filtering characteristics with sharp transition. Thus, it may be modeled as m-derived filter section. Accordingly, T-type LC equivalent circuit is proposed and LC parameters are extracted. A planar composite lowpass filter is designed by image parameter method and implemented by different DGS units. A composite filter requires at least three filter sections, of which two m-derived sections and one constant k-section. In proposed scheme, one such m-derived section is directly replaced by proposed DGS unit, whose cut-off frequency is same as that of designed m-derived section. The other m-derived section implemented by proposed DGS unit divided into equivalent two L-sections which will act as a termination for impedance matching. A constant k-section has been realized by a dumbbell shaped DGS having same cutoff frequency. Here lumped LC parameters are directly replaced by the equivalent LC values of the DGSs and therefore, produce almost ideal filter characteristics by overcoming the limitations of microstrip technology.

L‐section matching with notches and its application for composite lowpass filter with spurious signal suppression

L-section matching circuits are used for various applications. Such circuits can be advanced to provide notch responses to suppress undesired spurious signals. The design guide that allows integration of notch responses in the L-section matching circuits is presented. With given impedance at the targeted matching frequency and notch frequencies, a matching circuit with the spurious signal suppressing notches can be simply designed based on the closed-form equations provided. A composite lowpass filter (LPF) based on the image parameter method is composed of two matching sections and two filter sections. Replacing conventional matching sections with the proposed L-section matching circuits, an LPF with spurious signal notches can be realised. The proposed matching circuit and filter with spurious suppression notches will bring an added dimension of design freedom for modern communication systems that demand stringent out-of-band requirements.

Ultra-wideband (UWB) Bandpass Filter with Cascaded Lowpass Filter on Multilayer Liquid-Crystal Polymer (LCP) Substrate

ABSTRACTAn ultra-wideband (UWB) bandpass filter with extended upper-stopband on multilayer liquid-crystal-polymer (LCP) substrate is presented in this paper. The proposed filter is designed to select the frequency band from 1.0 to 20 GHz. The filter consists of two parallel-coupled stub-loaded resonators separated by a composite lowpass filter. The composite lowpass filter is implemented to obtain a very wide rejection band. The proposed filter is fabricated using multilayer LCP technology. Excellent agreement between expected and measured results of the filter is obtained. The measurement results show that the fabricated filter has a fractional bandwidth of 180% and a very low insertion loss of less than 0.6 dB at center frequency of 10.5 GHz. The measured filter has a wide stopband and an excellent rejection level higher than 40 dB.

Design of Compact Composite Microstrip Low Pass Filter Using MEMS Technology

This paper presents the design technique of a compact composite microstrip filter operating at ultra high frequency (UHF) band and its fabrication using micro-electro mechanical system MEMS technology. The fringing compensation method is applied into the design of the microstrip line transformation from lumped element. The filter lumped circuits and microstrip line circuit were designed and simulated using Advanced Design Software (ADS) and fabricated on silicon substrates to obtain the best filter characteristic based on S-parameter. The measured and simulated results have achieved a good agreement within the frequency of interest. This shows that the fringing compensation method of transforming lumped element into microstrip line is able to solve the conventional design of complexity size of circuit of composite low pass filter (LPF) into microstrip line. The proposed filter design can replace the conventional filters in wireless communication as they offer better performance at lower cost in the RF microwave communication applications.

Design Technique and modification of Power line filter using passive lumped components

A unique design technique of power line filter is being proposed. It is based on the conventional technique of composite low pass filter. The equivalent circuit of the composite low pass filter is being presented in the two different modes by considering the modal propagation of noise. The consideration of composite LPF is taken into account in the design technique of power line filter. In order to accurately predict the insertion loss of the filter the effects of non-ideal behaviour of the passive lumped components are considered. It is based on the parasitic effect of the passive lumped elements. The filter is then characterized using S-parameters. The response of the filter's circuits is simulated using advanced design software (ADS). Keywords: Conducted emission, Composite filter, electromagnetic compatibility, lumped elements, and power line filter. I. Introduction Switching and modulation techniques are used for efficient use of electrical power. Widely used Switched mode power supplies (SMPS) for powering today's electronics loads is a most common example. Unfortunately, all the power control techniques deliberately distort sinusoidal wave form of power frequency and generate unwanted interfering signals. Obviously, they all are often cited as one of the main source of conducted emission (CE). Usually the power supplies which are using controlling techniques cannot comply with the strict electromagnetic compatibility (EMC) regulations. In order to meet the limit set for conducted EMI, power supplies require a filter at its input. Conducted EMI generated through particular equipment gets coupled into other equipments mostly through power line cables. CE can be controlled by using filters and increasing line impedance. Conducted EMI has two components: The common mode (CM) interference and differential mode (DM) interference. The coupling mechanisms of these interferences are different (4). The difference in the direction of propagation of these coupling currents along the phase and neutral line, leads to differential mode ( ) current and common mode ( ) current. Therefore design of EMI filters demand decoupling of these two modes (2). This paper attempts to describe a design technique for Power Line filter using classical design technique. 1.1 Characterization of common mode & differential mode currents

Comparison Study on Chebyshev and Composite lowpass Filter for Harmonic Rejection in Two Ways Radio

The paper is on a comparison study on Chebyshev and Composite lowpass filter designed at 300-400 MHz used for harmonic rejection in two ways radio. The filter is used to attenuate harmonic that generated by power amplifier to prevent from radiating out through the antenna. The filter's circuits were first simulated using Advanced Design Software (ADS) to obtain the best filter characteristic based on S-parameter to see whether they met the specification for two way radio or not using the tuning and optimization features in AD S. The final low pass filter circuits were fabricated using chip capacitor and chip inductor components on printed circuit board. The S-parameter were measured using network analyzer. It was found that the fabricated had similar trend as simulated one. However, the cutoff frequencies are slightly different from what are intended to design. The simulated result showed the composite filter was found to be the best low pass filter and able to perform the better filters response. On the other hand, the fabricated Chebyshev filters was found to be the better filter output response.

A compact realization of composite low-pass filter for monolithic microwave integrated circuit applications

A compact realization of composite low-pass filter is presented in this article. The filter is realized using on-chip spiral inductors and metal–insulator–metal capacitors and features an attenuation pole near the cutoff frequency leading to a sharper attenuation response. As well, it offers good matching properties in the passband. Space-mapping-based algorithm is used in the design/optimization of spiral inductors toward achieving high quality factors at the filter cutoff frequency. The realization of the proposed filter is compact in size, suitable for monolithic microwave integrated circuit applications, and exhibit broad upper stopband frequency characteristics. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

Compact planar and vialess composite low-pass filters using folded stepped-impedance resonator on liquid-Crystal-polymer substrate

A compact composite low-pass filter, designed by the image parameter method and semilumped component approach, will be described and results for cutoff frequency ranging from C- to V-band will be presented. This composite design combines four filter sections and the presence of a strong attenuation pole near the cutoff frequency provides an extremely sharp attenuation response, while ensuring good matching properties in the passband, making this filter design very attractive for harmonic spurious response suppression or diplexing. The lumped-element schematic of the filter has been implemented using a combination of a stepped-impedance filter and folded stepped-impedance resonators. The overall folded layout has been optimized using full-wave simulation and occupies an ultra-compact area of only 5/spl times/5 mm/sup 2/ for a C-band filter. Measured results exhibit rejection of the attenuated pole greater than 40 dB. Similar filter designs have been realized for C- and V-bands. These filters have been fabricated on a liquid-crystal-polymer substrate demonstrating a high performance, ultra-compact, and very low-cost solution for RF and millimeter-wave applications.