E. Rius

An original topology of dual-band filter with transmission zeros

This paper reports on a new topology of high-performance dual-band filters. This topology is derived from the Dual Behavior Resonator (DBR) filter. The resulting resonator is directly dual-band. It allows the control of two bandpasses separated by a transmission zero to ensure a high rejection level between them. Moreover, two other transmission zeros are located on either side of the two bandpasses. The possibilities offered by this structure are discussed and measurements are presented to validate the method.

Narrow bandpass filters using dual-behavior resonators based on stepped-impedance stubs and different-length stubs

Dual-behavior resonators (DBRs) are based on the parallel association of two different bandstop structures, which implies a constructive recombination. Two kinds of stubs, stepped-impedance and different-length stubs, are examined in this paper. The first section concerns stepped-impedance stubs. We have previously reported some simplifications of the fundamental equations. Here, we propose a new simplification together with synthesis; both allow an independent control of the two attenuated bands. In a second section, a DBR composed of two uniform stubs of different lengths is studied instead of two stepped-impedance open-circuited stubs. This implies a greatly simplified synthesis and implementation. Some other structures combining short- and open-circuited stubs are also introduced. Throughout the paper, simulations are proposed to illustrate the possibilities offered by such topologies. Experimental results in microstrip technology are also presented in order to validate our idea. Finally, benefits and drawbacks of the different structures are discussed.

MEMS switchable interdigital coplanar filter

This paper presents a tunable interdigital coplanar filter with tapped-line feedings. Microelectromechanical systems capacitors are used as a high contrast capacitive switch between a quarter-wavelength resonator and an open-ended stub to perform the frequency shift. A two-pole tunable filter with a 13% relative bandwidth has been designed, fabricated, and measured. The center frequency can be switched from 18.5 to 21.05 GHz with low return losses (less than 15 dB) and low insertion losses (3.5 dB).

Bandwidth and central frequency control on tunable bandpass filter by using MEMS cantilevers

This paper deals with a tunable bandpass filter topology which controls independently and simultaneously both the central frequency and bandwidth. This tunable filter results from the association of MEMS cantilevers, used as variable capacitors, with an original passive topology. The latter is based on dual behavior resonators (DBRs), each of them is constituted of low- and high-frequency open-ended stubs. The associated filter electrical response is characterized by tunable frequency transmission zeros. A millimeter bandpass filter with central frequency and relative bandwidth tunability of about 10 and 75%, respectively, is presented.

Integration of optimized low-pass filters in a bandpass filter for out-of-band improvement

We propose an original structure for the design of high performance filters with simultaneously controlled band-pass and band-reject responses. The band-reject response is controlled due to the integration of low-pass structure. Thus, the spurious resonances of the band-pass filter are rejected up to the low-pass filter ones. In this way, we have to optimize the response of the low-pass structure in order to control the out-of-band response of the band-pass filters.

Integration of optimized low-pass filters in band-pass filters for out-of-band improvement

We propose an original structure for the design of high performance filters with simultaneously controlled band-pass and band-reject responses. The band-reject response is controlled due to the integration of low-pass structure. Thus, the spurious resonances of the band-pass filter are rejected up to the low-pass filter ones. In this way, we have to optimize the response of the low-pass structure in order to control the out-of-band response of the band-pass filters.

Design of narrow-band DBR planar filters in Si-BCB technology for millimeter-wave applications

This paper discusses a method used to design planar bandpass filters for millimeter-wave applications in U- and W-band frequency ranges. For technical reasons, these filters have to be implemented on silicon-based technology. So as to decrease the insertion losses levels inherent in silicon substrate, we propose a thin-film microstrip-like technology implemented on a benzocyclobutene layer. In addition, a dual-behavior resonator-based filter topology enabled us to fit a hardened specification. In association with this new topology, we employed an automated design procedure that combines both circuit and full-wave simulations. It is based on a statistical sensitivity study performed by design-of-experiment analysis.

Wide- and narrow-band bandpass coplanar filters in the W-frequency band

This paper deals with the design of passive coplanar devices in the W-frequency band. As long as coplanar transmission lines are correctly dimensioned, analytical models based on quasi-TEM approximation can be used. Such models are associated with a correct definition of the reference planes at the junctions and employed for junction discontinuities, T- and cross-junctions. In order to validate these assertions, simulated and experimental data on classical quarter-wavelength shunt-stub filters are first presented. Then the design of traditional coupled-line filters is examined. The problems in terms of insertion loss associated with these kinds of narrow-band applications are discussed here. Minimization of insertion losses requires increasing the width of the strips. Consequently, the design becomes complex and modeling using transmission-line models less accurate. Nevertheless, as an optimization procedure is needed to tune the filter theoretically, such a very fast design method is necessary. Simulated and experimental results in the range 500 MHz to 110 GHz are compared throughout the paper.

Planar tri-band filter based on dual behavior resonator (DBR)

This paper reports on the application of dual behavior resonators to design triband filters. The principle is briefly presented by considering monoband, dual-band and triband filters. A circuit is proposed by using an approximate synthesis. Then, a hybrid (electromagnetic / circuit) simulation is performed to take into account the parasitic effects induced by the junction discontinuities and to allow a fast triband optimization in the same time. An example of layout with associated simulated and experimental results is proposed.

Theoretical and experimental study of various types of compensated dielectric bridges for millimeter-wave coplanar applications

This paper describes a new approach for the integration of dielectric bridges in microwave-integrated-circuit uniplanar technology. Taking into account the electrical influence of these elements on coplanar waveguide, a simple way to compensate these parasitic effects is presented. It consists of locally tuning the dimensions of both the bridges and associated compensation lines. Theoretical and experimental results on coplanar waveguides and T-junctions are given for the millimeter frequency range. Finally, to validate the proposed technique, a bandpass filter including compensated dielectric bridges is implemented.