Eden Corrales

Equivalent circuit modeling of coupled resonator filters

Using the stacked crystal filter (SCF) concept, a coupled resonator filter (CRF) can be interpreted as a device in which 2 piezoresonators are stacked on top of each other in such a way that a certain degree of acoustic interaction occurs. The work presented in this paper reports a novel all-electrical model for the CRF. The model associates acoustical coupling with an equivalent electrical coupling between resonators. The resulting equivalent circuit makes it possible to apply classical filter synthesis techniques directly based on the coupling control between resonators. It complements with a synthesis approach the analysis approach of the Mason model.

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.

Dual-Band Mixer Using Composite Right/Left-Handed Transmission Lines

The concept of composite right left-handed transmission lines provides for one additional degree of freedom in realizing arbitrary dual-band frequency response devices. In this letter, an arbitrary dual-band operation mixer, based on the classical balanced mixer topology is proposed. The prototype demonstrates the mixer performance for a ratio of 2.5 between the two operation bands (860 MHz and 2,150 MHz). The conversion losses are better than 8.5 dB in both bands.

Closed-Form Expressions for the Design of BAW CRF Acoustic Inverters

A bulk acoustic wave coupled resonator filter is a device in which two thin film bulk acoustic wave resonators are stacked on top of each other separated by a set of passive layers which control the degree of acoustic interaction between resonators contributing to the conformation of the radiofrequency passband response. The set of passive layers implements an impedance inverter which has to fulfill the desired coupling value. The variation of the acoustic lengths of the coupling layers gives the degree of freedom to implement the desired inverter. In this work, a set of closed-form expressions are provided to obtain the coupling layers thicknesses without any time-consuming optimization procedure. The provided solution gives an explanation to the underlying fundamentals that take place in a successful optimization procedure.

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.

A Dual-Band 180-Degree Hybrid Coupler Based on Coupled-Line Sections

This letter presents a novel 180 degree hybrid coupler structure based on coupled-line sections which offers a compact circuit and a dual-band operation. The structure is based on 90 degree and 180 degree coupled lines suitable to offer a 180 degree hybrid coupler behavior at two frequency bands when the even and odd impedances of the coupled-line sections are properly determined. The circuit presents a symmetry plane that enables an even/odd analysis. The dual-band operation of the structure has been verified by means of a prototype implemented in microstrip technology operating at 2.4 and 5 GHz.

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.

Design of a Coupled Resonator 3dB power divider based on BAW technology

Conventional power dividers based on quarter-wavelength lines are not adequate for the high level of miniaturization demanded for new wireless communications systems. The use of Bulk Acoustic Wave (BAW) technology overcomes the miniaturization issue. The design approach for an equal power divider based on BAW Coupled Resonator Filters (CRF) is introduced. A 3 dB power divider designed for W-CDMA receivers is presented. The proposed structure formed by three CRF sections shows a Chebyshev filtering response with 20 dB return loss. The designed CRF power divider simplifies the fabrication because almost all the multilayer films are uniform for all the CRF sections.

A dual-band resonator in Bulk Acoustic Wave technology

Filters with the capacity of operation in different frequency bands are important components in new multi-band wireless communication systems. The use of dual-band resonators is a possible mechanism to create the dual-band filter. In this paper, a novel dual-band resonator based in Bulk Acoustic Wave technology is proposed. Limitations in the dual-band resonator for designing dual-band filters have been studied. A Galileo/GPS dual-band filter in ladder-type topology is designed using the proposed dual-band resonator.

Direct Coupling Matrix Synthesis of Bandstop Filters

This work presents a straightforward way to obtain the coupling matrix of a bandstop flltering response from the original bandpass coupling matrix. The generated bandstop coupling matrix implements a response where the bandwidth is deflned at the equiripple return loss of the lower and the upper passbands.