A general procedure for the design of bulk acoustic wave filters

This article presents a procedure for the design of bulk acoustic wave (BAW) filters. The procedure consists of optimizing the modified Butterworth‐Van Dyke model of each resonator, considering appropriate technological parameters. The approach is demonstrated first to design a classical aluminum nitride‐based BAW filter but remains valid for other piezoelectric layers, considering either longitudinal or transverse acoustic wave coupling. The approach is finally applied to the design of a lithium niobate (LiNbO₃) BAW filter for wide‐band filtering applications. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A surface-mountable membrane supported filter

A silicon micro-machined filter with a simple planar integration on an other substrate is proposed in this article. The excitation is made from the top of the shielding substrate of a membrane supported micro-machined filter. Packaging and inter-connection are included in the design. Experimental results are presented on a two pole 30 GHz, 4% fractional bandwidth filter with a quality factor of 602 and insertion loss of 1.8 dB. Such a filter can be easily integrated in any circuit using flip-chip technology.     

A study on controllable aluminium doped zinc oxide patterning by chemical etching for MEMS application

This present work reports on the study of controllable aluminium doped zinc oxide (AZO) patterning by chemical etching for MEMS application. The AZO thin film was prepared by RF magnetron sputtering as it is capable of producing uniform thin film at high deposition rates. X-Ray diffraction (XRD) and atomic force microscopy (AFM) characterization were done to characterize AZO thin film. The sputtered AZO thin film shows c-axis (002) orientation, low surface roughness and high crystalline quality. To pattern AZO thin film for MEMS application, wet etching was chosen due to its ease of processing with few controlling parameters. Four etching solutions were used namely: 10 % Nitric acid, 10 % Phosphoric acid, 10 % Acetic acid and Molybdenum etch solutions. For the first time, chemical etching using Molybdenum etch that consist of a mixture of CH₃COOH, HNO₃ and H₃PO₄ was characterized and reported. The effect of these acidic solutions on the undercut etching, vertical and lateral etch rate were studied. The etched AZO were characterized by scanning electron microscopy (SEM) and stylus profilometer. The investigations showed that the Molybdenum etch has the lowest undercut etching of 7.11 µm, and is highly effective in terms of lateral and vertical etching with an etch ratio of 1.30. Successful fine patterning of AZO thin films was demonstrated at device level on a surface acoustic wave resonator fabricated in 0.35 μm CMOS technology. The AZO thin film acts as the piezoelectric thin film for acoustic wave generation. Patterning of the AZO thin film is necessary for access to measurement probe pads. The working acoustic resonator showed resonance peak at 1.044 GHz at 45.28 dB insertion loss indicating that the proposed Molybdenum etch method does not adversely affect the device’s operating characteristics.

     

Business communications standardization in ETSI

Enterprise networks are in the process of a major and rapid evolution toward IP. At the same time, the 3GPP IP multimedia subsystem is gaining momentum in the telecom industry as the target architecture for delivering and controlling multimedia services in carrier-grade IPbased networks. As a logical consequence, standards are emerging that enable the support of business trunking and hosted enterprise services using the IMS. This article provides insight into the benefits of this approach and takes an in-depth look at related ETSI standards.     

A Two-Pole Lumped-Element Programmable Filter With MEMS Pseudodigital Capacitor Banks

This paper presents a novel two-pole reconfigurable bandpass filter on alumina substrate for applications in X- and S-bands. An analytical approach was followed for synthesis of multiple filtering characteristics. A microstrip network on alumina was then optimized to implement a set of switched filtering functions. Finally a reconfigurable filter was fabricated and tested in order to validate the proposed approach. This filter exploits five 3-bit capacitor banks controlled with microelectromechanical systems ohmic switches to achieve 12 states with 37.5% tuning range between 1.51-2.26 GHz. Several tuning mechanisms are demonstrated including frequency, bandwidth tuning, and frequency + bandwidth tuning. Good agreement with theoretical results has been obtained.     

A complete UMTS transmitter using BAW filters and duplexer: A 90‐nm CMOS digital RF signal generator and a 0.25‐μm BiCMOS power amplifier

A complete UMTS transmitter is proposed. It is composed of a radiofrequency (RF) signal generator, a power stage, and a bulk acoustic wave (BAW) duplexer. The 90‐nm CMOS digital RF signal generator is based on a third‐order delta‐sigma modulator using innovative design techniques to increase work frequency and a BAW filter to get rid of out‐of‐band quantization noise. The filter exhibits very high rejection, 3 dB of insertion losses at 1.95 GHz for a 3% fractional bandwidth. The 0.25‐μm BiCMOS power stage feeds a BAW duplexer that allows to share a common between W‐CDMA emission and reception. This 4 × 4 mm² duplexer, built with flip‐chipped BAW on glass substrate, ensures good isolation. The full transmitter measurements show the compliance with respect to spurious emissions in the different frequency bands and an EVM measurement at the state of the art (<5%). © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Simultaneous standardisation of modules and their components: a global economic perspective

This paper deals with the problem of simultaneous standardisation of a set of modules and of several sets of components that may be combined in these modules. The aim is to minimise future costs of production and procurement. We introduce a multilevel standardisation that permits to link the level of forecasts used in manufacturing companies with the modules. This formulation determines the composition of the module i.e. their Bill of Material instead of using a predetermined one. The model takes into account coupling restrictions between components and also permits to modelise the possibility of lifting some of them through ‘junction components’. Our model proposes an efficient approach to deal with temporal dimension in the standardisation process. This approach is illustrated with a real case from the automotive industry and some of the related implementation problems are discussed.     

Bulk acoustic wave filters synthesis and optimization for multi-standard communication terminals

This article presents a design methodology for bulk acoustic wave (BAW) filters. First, an overview of BAW physical principles, BAW filter synthesis, and the modified Butterworth-van Dyke model are addressed. Next, design and optimization methodology is presented and applied to a mixed ladder-lattice BAW bandpass filter for the Universal Mobile Telecommunications System (UMTS) TX-band at 1.95 GHz and to ladder and lattice BAW bandpass filters for the DCS1800 TX-band at 1.75 GHz. In each case, BAW filters are based on AlN resonators. UMTS filter is designed with conventional molybdenum electrodes whereas DCS filters electrodes are made with innovative iridium.