Jordi Verdu

Branch-Line Coupler Based on Edge-Coupled Parallel Lines With Improved Balanced Response

A conventional branch-line coupler is flat-balanced, in terms of magnitude and phase, in a narrow frequency band due to the quarter-wave length requirement in the transmission lines. In this paper, a novel branch-line structure is presented in order to overcome this limitation. Loading the horizontal transmission lines with a pair of open-end series stubs, the magnitude and phase balance becomes flatter in a wider frequency range. However, the proposed structure cannot be fabricated, for which an equivalent circuit using edge-coupled parallel lines has been used. The measurement of this device shows a relative bandwidth of 82.5% for 2 dB magnitude and 72% for plusmn5deg phase balance condition.

PROCEDURE FOR THE DESIGN OF LADDER BAW FILTERS TAKING ELECTRODES INTO ACCOUNT

This paper aims to complete a published systematic methodology for the design of ladder BAW filters in order to include the effect of the electrodes, since infinitely thin electrodes are assumed in this design methodology. The new procedure is validated against the work of other authors, finding very good agreement between results.

Design, fabrication and measurement of a GPS-Galileo dual-passband filter

This paper presents the design, fabrication and measurement of a GPS-Galileo dual-passband filter. The applied synthesis methodology is based on a frequency transformation of the Chebyshev low-pass prototype, and unlike most of conventional synthesis methodologies allows us to design dual-passband filters as classical coupled-resonator filters. The filter is designed and fabricated in microstrip technology which offers a very cost effective device with reduced size and weight. The measured insertion loss is about 2 dB in the lower band and 3.5 dB in the higher band. Lower insertion loss is possible using resonators with higher unloaded quality factor, for example cavity resonators, but on the other hand this type of resonators presents much higher cost, size and weight.

Electric Equivalent Circuit for the Thickened Edge Load Solution in a Bulk Acoustic Wave Resonator

With the aim to improve the performance of Bulk Acoustic Wave resonators, the thickened edge load can be included on the top electrode. Using this solution, the energy trapping concept is forced, and lateral unwanted resonances are not present in the electrical behavior of the resonator. The way to design such a thickened edge load entails, on one hand, the presence of a resonant mode given by the thickened edge load; on the other hand, the degradation of the electromechanical coupling coefficient of the main thickness mode. In order to study the previous phenomena, the electric equivalent circuit has been developed. The obtained results have been validated with the three-dimensional simulations and compared with manufactured resonators.

Double-Ladder Filter Topology for a Dual-Band Transmission Response Based on Bulk Acoustic Wave Resonators

Filters based on bulk acoustic wave resonators present very good performance, small size and compatibility with IC technology. However, the traditional configurations present only one frequency transmission band. In this work, a configuration based on electrically coupled BAW resonators has been developed in order to obtain a dual-band response, where each of these bands can be allocated at a desired frequency. In order to validate the proposed topology, a filter response using measured resonators is shown.

Analysis Technique for Asymmetrically Coupled Resonator Structures

Asymmetrical acoustically coupled structures are present in several acoustic applications. Specifically when they are used in filter design, some configurations provide unexplored and special response characteristics with high selectivity and relatively wide bandwidths. The relationships between geometries, configurations, and response specifications do not rely on a direct link. In this work, a novel approach to the analysis of these structures is presented as well as a model of an asymmetrical bulk acoustic wave coupled resonator filter obtained from the analysis presented.

Design of Three-Pole Bulk Acoustic Wave Coupled Resonator Filters

The control of longitudinal coupling in bulk acoustic wave (BAW) resonators makes it possible to design multilayer coupled resonator filters (CRF) with a desired response. This paper presents the methodology to face this kind of designs with a set of closed-form expressions that allow to control the coupling between resonators, and to determine the structure geometry of a three-pole CRF. A network transformation from the Mason model to an equivalent electric circuit makes it possible to apply the insertion loss filter design method. An UMTS RF filter has been designed using the proposed methodology.

Dual bandpass ladder-type filter

Filters based on Bulk Acoustic Wave (BAW) resonators present very good performance, small size and compatibility with the standard IC technology processes. However, the traditional configurations of such filters present only one frequency transmission band. In this work, a configuration based on electrically coupled BAW resonators has been developed in order to obtain a dual-band response, where each of these bands can be allocated at a desired frequency. In order to validate the proposed topology, a filter response using measured resonators is shown.

Systematic synthesis methodology for the design of acoustic wave stand-alone ladder filters, duplexers and multiplexers

Usually, the design of acoustic wave devices is mainly entrusted to optimization techniques due to the stringent constraints imposed by the technological feasibility of acoustic resonators and the challenging electrical specifications. A stringent transmission response and very restrictive technological factors make the designing a complex and challenging task. The objective of this work is to describe a methodology for the direct synthesis of ladder-type acoustic filters: stand-alone, duplexers or multiplexers (Carrier aggregation). The methodology is native oriented to accommodate technology, and also works with cross-couplings.

Relation between electromagnetic coupling effects and network synthesis for AW ladder type filters

The presence of electro-magnetic feedthrough between package ports in the design of filter based on acoustic wave resonators may cause degraded isolation levels and transmission zeros vanishing. These effects come from the presence of complex singularities, but also from internal phase shift requirements for a full network synthesis. This paper proposes a filter design procedure with cross-couplings that takes a set of leakages into account, providing the exact resonator parameters that maintain the levels of attenuation for acoustic wave filters.