On a class of low-reflection transmission-line quasi-gaussian low-pass filters and their lumped-element approximations (original) (raw)

Design of digital filters from LC ladder networks

A design procedure is given which enables digital filters to be derived directly from ladder LC filters. The derivation is based on an element-by-element transfer of the ladder components to the digital domain. The manner in which such a transfer is achieved is dependent on linear voltage-current transformations, a special case of which is that relying on scattering parameters which has already been described by this author and by others elsewhere. A specific set of constraints are imposed on the transformations in this paper so as to satisfy the readability condition and also to ensure that the digital filters thus derived have transfer functions which are identical to the original ladder transfer function, generally modified by a constant multiplier, as viewed through the bilinear complex frequency transformation. Two special cases of the general approach presented in this paper show that the digital filter structures so derived have a low attenuation sensitivity to multiplier variation, which is consistent with the expectation for the low sensitivity properties of the doubly-terminated lossless ladder filters.

IJERT-Design and Implementation of Microstrip Line Based Stepped Impedance Low Pass Filter

International Journal of Engineering Research and Technology (IJERT), 2021

https://www.ijert.org/design-and-implementation-of-microstrip-line-based-stepped-impedance-low-pass-filter https://www.ijert.org/research/design-and-implementation-of-microstrip-line-based-stepped-impedance-low-pass-filter-IJERTCONV9IS03046.pdf Filters are noteworthy RF and Microwave components in communication systems. Lumped element filters using capacitors and inductors are unrealistic for compact designs of wireless communications equipment, especially hand-held devices. Distributed element filter design offers a much smaller area and are low profile. With the initiation of advanced substrate materials offering high dielectric constants with low loss, the size reduction with preserved efficiency is greatly enhanced. Transmission line filters can be easy to fabricate, depending on the type of transmission line used. This paper proposes the microstrip line stepped impedance low pass filter. This paper presents about the design, testing and fabrication of microwave low pass filter by using micro strip layout. The development of the micro strip filter is simulated by using CST2019 software followed by practical measurements using R&S make Vector Network Analyzer. The higher cutoff frequency is 2.4GHz and has insertion loss is-23dB at 3.9GHz.

Design of Chebychev's Low Pass Filters Using Nonuniform Transmission Lines

Journal of ICT Research and Applications, 2015

Transmission lines are utilized in many applications to convey energy as well as information. Nonuniform transmission lines (NTLs) are obtained through variation of the characteristic quantities along the axial direction. Such NTLs can be used to design network elements, like matching circuits, delay equalizers, filters, VLSI interconnections, etc. In this work, NTLs were analyzed with a numerical method based on the implementation of method of moment. In order to approximate the voltage and current distribution along the transmission line, a sum of basis functions with unknown amplitudes was introduced. As basis function, a constant function was used. In this work, we observed several cases such as lossless and lossy uniform transmission lines with matching and arbitrary load. These cases verified the algorithm developed in this work. The second example consists of nonuniform transmission lines in the form of abruptly changing transmission lines. This structure was used to design a...

Design and Simulation of Low Pass Filters for UHF Based on Microstrip Lines

physica status solidi (b), 2000

An algorithm was developed for the synthesis of the transmission line structure for filters to be designed on microstrip lines within the UHF range. In this case, the generalized algorithm optimizes a predetermined objective function, in which electrical parameters of the filter are calculated straightforward by means of recurrent equations. Optimization is carried out for a minimum out-band energy criterion. The length of the microstrip line can be computed for desired values of source impedance, load impedance and wavelength. This procedure can be extended to any geometry of microwave transmission line, as well. The above algorithm was compared to the well-known method based on the representation of the transfer function of low-pass filter through prototype structures of equivalent concentrated transmission lines. As a result of comparison, it was found that the accuracy for the generalized algorithm was higher than for the indirect representation method. The synthesized microstrip lines are to be made up of a set of conductor segments with physical parameters chosen according to the obtained values from the developed algorithms.

Butterworth Filter Design at RF and X-band Using Lumped and Step Impedance Techniques

Low pass filters are widely used in telecommunications for a variety of commercial and military applications. The design and simulation technology differs according to the cut-off frequency. In this work we design, simulate and compare various types of passive Butterworth filters, regarding their order and the type of topology used, for RF frequencies using lumped components with cut-off frequency around 3 KHz. Then, low frequencies are transferred to microwave frequencies and a low pass even order Butterworth microwave filter, using step impedance microstrip lines with cut-off frequency around 3 GHz is analyzed, designed and simulated.

Low pass filter design with improved stop‐band suppression and synthesis with transformer‐free ladders

2021

A new method to design transformer-free low pass (LP) ladder network with improved stop-band suppression performance is introduced. The parametric representation of back-end impedance of LP filter network is established with minimum impedance part and a Foster reactance part. The constructed impedance function is optimized by using real frequency technique. It has been shown that the proposed method provides LP filters which have superior stop-band suppression in comparison with classical transfer function-based filters with same complexity. The synthesis of the LP filter is obtained with the proposed element extraction procedure and resulted with fully realizable network elements in ladder form. An LP filter design and application by employing the proposed technique is provided. The measurement results of the prototyped filter are presented. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A Review of Technique to Convert Low Pass Filter Into Microstrip Line Circuit

2015

The purpose of this paper is briefly describes review of techniques design a lumped element low pass filter prototype into microstrip line circuits that is normalized in terms of impedance and frequency range. There are several methods have been consequential or developed and used to provide as well as improve the conversion into microstrip line circuit by researchers to interpret the lumped element into a microstrip filter with simple and efficient techniques and which accomplish the design specification. There are some main features of the frequency at microstrip low pass filters to improve frequency responses, to obtain the sharp cutoff frequency response and low ripple corresponding to low return loss in the passband. This paper will investigates different techniques undergoes by some of the research that has been performed in the area of transforming lumped element LPF into microstrip line circuits and the future objectives that must be accomplished for achieved more efficientl...