Piezoelectric Materials for Advanced Integrated RF Components
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1075-J03-01
Piezoelectric Materials for Advanced Integrated RF Components Mahmoud Al Ahmad, Fabio Coccetti, and Robert Plana LAAS CNRS, 7 avenue du Colonel Roche, Toulouse Cedex 4, France
Abstract This paper will ¯rst address the piezoelectric material characterization using a capacitance measurement technique. An original simple and e±cient technique for the determination of the jd33 j piezoelectric coe±cient of lead zirconate titanate thin ¯lms is described. Classical capacitor plate theory and piezoelectric material analysis are used to calculate the capacitance variation in lead zirconate titanate ¯lm, enabling piezoelectric coe±cient to be determined. The technique outlined here avoids the use of mechanical/optical apparatus that may require heavy preparation of sample substrate geometry. Then, this work also treats design and fabrication issues associated with innovative tunable front-end components which combine two di®erent ceramic technologies, namely multilayer ceramic circuit boards (low temperature co¯red ceramics or LTCC) and piezoelectric actuator technology within a single device.
Introduction The need for tunable front-end components is particularly arising due to the increasing number of wireless services and associated frequency bands [1]. A single ¯lter with a wide voltage-controlled tuning range would enable radio manufacturers to reduce costs by using a single frequency-agile device instead of a series of ¯xed frequency ¯lters [2]. A variety of tuning-concepts has therefore been investigated over the years as described in [3]-[4]. Particularly noticeable are semiconductor varactor diodes [5], MEMS capacitors [6], paraelectric capacitors [7]-[9], and piezoelectrically controlled circuits [10]. All of these approaches come with their individual bene¯ts and drawbacks in terms of power consumption, speed, reliability, microwave losses or drive voltage level. In the ¯eld of micro and nanosystems, there are a lot of e®orts to improve the sensitivity, the e±ciency and more generally the overall performances of the miniaturized sensors and actuators. One type of material is gaining more and more importance is the piezoelectric material where there is a strong interaction between the mechanical and electrical properties that translates into innovative components and circuits architectures. Lead zirconate titanate (PZT) is employed due to its large elastic density per volume unit [11]. However, the development of PZT based components will necessitate a deep understanding of its properties. Therefore, it has become increasingly important to characterize the activity of piezoelectric materials under conditions relevant to their applications.
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Piezoelectric Material Characterization Using RF Technique
Consequently di®erent methods have been sought to measure the piezoelectric activity, such as laser interferometry [12,13], resonance techniques [14], cantilever °exure [15,16], wafer °exure [17] and pneumatic loading techniques [18]. From the data known, di®erences between the various reported technique
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