A new simulation model for nonlinearity of SAW resonator filters
In the design stage of SAW duplexers for 3G handsets, a new simulation method which is predictable for the frequency characteristics of the nonlinearity has been desired in order to improve the intermodulation distortion and/or the triple beet. Recent SAW duplexers consist of not only ladder type filters but also DMS filters. In this paper, a novel simulation method of nonlinear signals, which is applicable for not only one-port SAW resonators but also DMS filters, has been proposed. Basic calculation model of the nonlinear current is derived by introducing nonlinear terms to the piezoelectric fundamental equation. In order to apply this model to IDT structure, we extend the equation to summation model of multi point electrodes. Good agreement between calculated results and measured values has been obtained.
Third order nonlinear distortion of SAW duplexers in UMTS system
Nonlinearity distortion characterization and accurate modeling techniques for leaky surface acoustic wave (LSAW) devices have been desired in the recently years due to the applications of the Radio Frequency (RF) SAW duplexers in the third-generation (3G) telecommunication system, such as Universal Mobile Telecommunications System (UMTS). In the work, we first discuss the approaches to measure and characterize the 3rd order harmonic generation of the resonators on lithium tantalate YXl42° wafer and YXl48° wafer, with resonance frequency of 800MHz to 900 MHz; Second, we present an effective nonlinear Butterworth-van-Dyke (BVD) model to simulate the multi-tone 3rd order intermodulation effects of a band 5 duplexer; simulation result vs. measurement of 3rd order harmonic generation, 3rd order intermodulation (IMD3) and triple beat are presented.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.