This letter describes a novel three-port absorptive limiter for frequency-selective circuits based on a configuration similar to a conventional 90° hybrid coupler. This circuit uses the switching behavior of common diodes to change between the nonlimiting and absorptive limiting states. Theoretical descriptions and designs are presented along with prototypes based on PIN diodes. Measurements of the limiting performance of the devices at approximately 2 GHz as a function of power demonstrate the viability of the concept.
Collado, J.; Rocas, E.; Verdú, J.; Mateu, J.; Hueltes, A.; Aigner, R. IEEE International Ultrasonics Symposium p. 1497-1501 DOI: 10.1109/ULTSYM.2014.0370 Data de presentació: 2014-09-05 Presentació treball a congrés
An equivalent circuit model to predict lateral modes occurring in real BAW resonators is proposed. The circuit model has been validated with FEM simulations of FBAR resonators and also with measurements of SMR resonators. The model allows to predict the electrical response of square-shaped and rectangular-shaped resonators without limitation on dimensions.
Collado, J.; Hueltes, A.; Rocas, E.; Mateu, J.; Booth, J.; O'callaghan, J.; Verdu, J. IEEE microwave and wireless components letters Vol. 24, num. 6, p. 415-417 DOI: 10.1109/LMWC.2014.2313583 Data de publicació: 2014-06-01 Article en revista
This letter describes a novel absorptive limiter for frequency-selective circuits. The proposed circuit allows the design of absorptive limiters based on a bi-state phase shifter, which is appropriate for integration into channelizing devices, such as hybrid-coupled input multiplexers. A preliminary prototype with shunt PIN diodes has been fabricated and measured to demonstrate the viability of the concept.
This paper evaluates the nonlinear effects occurring in a bulk acoustic wave (BAW) filter which includes barium strontium titanate (BST) capacitors to cancel the electrostatic capacitance of the BAW resonators. To do that we consider the nonlinear effects on the BAW resonators by use of a nonlinear Mason model. This model accounts for the distributed nonlinearities inherent in the materials forming the resonator. The whole filter is then implemented by properly connecting the resonators in a balanced configuration. Additional BST capacitors are included in the filter topology. The nonlinear behavior of the BST capacitors is also accounted in the overall nonlinear assessment. The whole circuit is then used to evaluate its nonlinear behavior. It is found that the nonlinear contribution arising from the ferroelectric nature of the BST capacitors makes it impractical to fulfill the linearity requirements of commercial filters.
This paper demonstrates that it is possible to find an ideal filter response (Chebyshev, Butterworth,..) considering the antenna as the last resonator of a filter under certain circumstances related with the antenna performance and the bandwidth of the filtenna device. If these circumstances are not accomplished, we can achieve excellent performance as well, by means of an iterative process the goal of which is defined by either a filter mask or a classical filter function itself. The methodology is based on the conventional coupling matrix technique for filter design and has been validated by fabricating a microstrip prototype using hairpin resonators and a rectangular patch antenna.
Rocas, E.; Collado, J.; Mateu, J.; Hueltes, A.; Verdu, J.; Booth, J.; Aigner, R. IEEE International Ultrasonics Symposium p. 1672-1675 DOI: 10.1109/ULTSYM.2013.0426 Data de presentació: 2013-07 Presentació treball a congrés
In this work we go beyond the usual temperature range for commercial applications and explore the functioning of Bulk Acoustic Wave (BAW) resonators down to cryogenic temperatures, to get the whole picture at understanding the physical tendency of the main parameters with temperature. This can ensure the proper functioning for specific applications where the device is exposed to extreme temperature variations.
Rocas, E.; Collado, J.; Aigner, R.; Mateu, J.; Hueltes, A.; Booth, J. IEEE International Ultrasonics Symposium p. 547-550 DOI: 10.1109/ULTSYM.2012.0136 Data de presentació: 2012-10 Presentació treball a congrés
We present a methodology to characterize BAW resonators both linearly and nonlinearly. The procedure uses physical modeling along with measurements that exploit different manifestations of the nonlinear phenomena to identify the dominant linear and nonlinear material properties. Such methodology allows obtaining consistent nonlinear material parameters by use of two independents measurements.
We present a methodology to characterize BAW
resonators both linearly and nonlinearly. The procedure uses physical modeling along with measurements that exploit different
manifestations of the nonlinear phenomena to identify the dominant linear and nonlinear material properties. Such methodology allows obtaining consistent nonlinear material
parameters by use of two independents measurements.
Aspect-Oriented Software Development (AOSD) supports systematic identification, modularisation, representation and composition of crosscutting concerns such as security, mobility, distribution and resource management. Its potential benefits include improved ability to reason about the problem domain and corresponding solution; reduction in application code size, development costs and maintenance time; improved code reuse; architectural and design level reuse by separating non-functional concerns from key business domain logic; improved ability to engineer product lines; application adaptation in response to context information and better modelling methods across the lifecycle.AOSD-Europe will harmonise and integrate the research, training and dissemination activities of its members in order to address fragmentation of AOSD activities in Europe and strengthen innovation in areas such as aspect-oriented analysis and design, formal methods, languages, empirical studies and applications of AOSD techniques in ambient computing. Through this harmonisation, integration and development of essential competencies, the AOSD-Europe network of excellence aims to establish a premier virtual European research centre on AOSD. The virtual research centre will synthesise the collective viewpoints, expertise, research agendas and commercial foci of its member organisations into a vision and pragmatic realisation of the application of AOSD technologies to improve fundamental quality attributes of software systems, especially those critical to the information society. It will also act as an interface and a centralised source of information for other national and international research groups, industrial organisations and governmental bodies to access the members? work and enter collaborative initiatives. The existence of such a premier research base will strengthen existing European excellence in the area, hence establishing Europe as a world leader.