This work evaluates the microwave properties of ferroelectric BaSrTi0 thin films by measuring the frequency response of several coplanar transmission lines and interdigital capacitor structures as a function of DC applied electric field from 100 Hz to 40 GHz. We use on-wafer calibration techniques to obtain accurate distributed capacitance and conductance of the structures, which are then reduced to geometry-independnet parameters: the complex permittivity vs. frequency, by using finite element simulations. To address the tuning at RF frequencies, we also measure the third harmonic and third order intermodulation products (IMD) for several frequencies whent he ferroelectric transmission lines are fed with two tones. Unlike measurements under DC electric field bias, thir harmonic and IMD measurements yield distributed parameters which are affected by the time dependence of the incident signals. By comparing both sets of distributed parameters (DC bias vs. RF bias), we evaluate the attainable time scales for tuning and model the nonlinear effects of ferroelectric transmission lines.
International Microwave Symposium
June 11-16, 2006
San Francisco, CA
IEEE MTT-S Microwave Week
Ferroelectric films, microwave measurements, nonlinear response, circuit modeling, response time.