A. Tag

Influence of dissipated power distribution on BAW Resonators' behavior

By taking the spatial distribution of the dissipated power into account the modeling of Bulk Acoustic Wave Resonators at higher power levels could be improved. The simulation results have been verified by measurements of vectorial scattering parameters during high power loads and by measurements of the temperature increase due to the self-heating by infrared thermography.

Polyharmonic Distortion modeling of RF BAW components

For the first time the Polyharmonic Distortion (PHD) model has been used to characterize the nonlinearities of Bulk Acoustic Wave (BAW) components. For that purpose a measurement setup has been developed by extending a nonlinear vector network analyzer with required external components enabling X-parameter measurements at high power levels. By discussion of selected components of the BAW resonators PHD model and performing simulations in an RF design environment the importance of PHD model for improved BAW filter design has been demonstrated.

Influence of temperature distribution on behavior, modeling, and reliability of BAW resonators

The influence of spatial inhomogeneous temperature distribution caused by dissipated power on BAW resonators behavior has been investigated for the first time. A novel modeling approach with an acceptable calculation time taking the temperature distribution into account has been developed allowing an improved modeling of BAW resonator behavior at high power levels. By applying the modeling approach it could be shown that the common way to use a measured TCF to determine the device temperature at high power levels is not generally valid and can lead to inaccuracies in life time predictions. The modeling approach has been verified by infrared temperature measurements of BAW resonators under high power loads.

Measurement setup for X-Parameter characterization of bulk acoustic wave resonators

In this work a modern measurement method has been utilized in order to characterize nonlinear behavior of bulk acoustic wave (BAW) solidly mounted resonators (SMR). Unlike typical nonlinearity characterization methods, the method which was employed here not only records amplitudes, but also the phase of generated harmonics. Furthermore, the relations between the harmonics of different order are given. The modeling approach being used is the poly harmonic distortion (PHD) modeling approach, realized by the measurement of X-Parameters. For that purpose it was necessary to extend a nonlinear vector network analyzer (NVNA) by external components in order to enable high power measurements. Afterwards, several optimization steps were required to perform phase calibration. This difficulty arose due to the high power incident tones and steep resonator impedance curves on the one hand and the limited power provided by the phase calibration standard on the other hand.

A Method for Accurate Modeling of BAW Filters at High Power Levels

A novel approach for multiphysics modeling of bulk acoustic wave (BAW) filters is presented allowing accurate and at the same time efficient modeling of BAW filters at high power levels. The approach takes the different types of losses and their spatial distribution into account in order to provide the required input for thermal simulation. The temperature distribution determined by thermal simulation is used to modify the geometry and the layer stack of each single resonator of the filter. In this way, the required input for modeling of electromagnetic (EM) and acoustic behavior at high power level is generated. The high accuracy of the modeling approach is verified by the measurements of the S-parameters and the temperature distribution by infrared thermography during high-power loads. Moreover, the influence of the nonlinear behavior on the frequency shift of the resonance frequency is investigated. For this purpose, a parameterized nonlinear Mason model has been combined with a 3-D EM finite-element method and the required nonlinear material parameters were determined by fitting simulation results to the measured polyharmonic distortion model (X-parameters) of a BAW resonator.

Multiphysics Modeling of BAW Filters

A novel approach for multiphysics modeling of BAW filters is presented allowing accurate and at the same time efficient modeling of BAW filters at high power levels. The approach takes the different types of losses and their spatial distribution into account in order to provide the required input for thermal simulation. The temperature distribution determined by thermal simulation is used to modify the geometry and the layer stack of each single resonator of the filter. In this way the required input for modeling of electromagnetic and acoustic behavior at high power level is generated. Moreover, the influence of the nonlinear behavior on the frequency shift of the resonance frequency is investigated. The high accuracy of the modeling approach is verified by measurements of the S-parameters and the temperature distribution by infrared thermography during high power loads.

Modeling nonlinear behavior of RF Bulk Acoustic Wave resonators

In this work, the Poly-Harmonic Distortion (PHD) model has been used to characterize the nonlinearities of Bulk Acoustic Wave (BAW) solidly mounted resonators (SMR). The new approach of using X-parameters for characterization and simulation of nonlinearities is described. The amplitude and phase of the fundamental mode and its harmonics up to third order have been measured and simulated by using the X-parameter framework. The simulation and measurement results for phase and amplitude of X-parameters describing the relations between incident and reflected harmonics of the same as well as different orders are shown. The X-parameter measurements of BAW components up to third order harmonics have been carried out with a nonlinear vector network analyzer (NVNA). These measurements under large-signal operating conditions were used to determine the nonlinear material constants responsible for the nonlinearity in BAW resonators.

Modeling of BAW filters for system level simulation

A behavioral model of a BAW resonator realized in VerilogA is presented. VerilogA models can be integrated in all leading RF design tools allowing simulations of BAW filters at a system and circuit level. In that way a coupled design of the conventional electronics and the electro-mechanical BAW is now possible. By using the presented model the system designer has the possibility to optimize both the conventional electronic and BAW components according to the system requirements simultaneously. The VerilogA model has been verified by performing optimization in Cadence and ADS.

Determination of temperature coefficients of thin film materials in RF BAW components

A new, accurate, and fast approach for determining the temperature coefficients of the thin film materials used in RF BAW components has been developed allowing the precise modeling of BAW components at different ambient temperatures. The presented method is based on the investigation of several resonance frequencies of the resonators with different layer-stacks. The problem of determining the temperature coefficients from broadband resonator simulations and measurements was formulated as an overdetermined linear system of equations and solved by using the weighted least square method. The presented approach has been verified by measurements.