Microwave frequency tuning and harmonic generation in ferroelectric thin film transmission lines

Abstract

We evaluate dielectric tuning on nanosecond time scales in ferroelectric Ba 0.3 Sr 0.7 TiO 3 thin films by measuring nonlinear harmonic generation at a fundamental frequency of 3 GHz. We compare the form of the distributed nonlinear capacitance per unit length C(V rf ) extracted from a simple model of harmonic generation in coplanar waveguide transmission line structures with the nonlinear capacitance C(V dc ) measured using a dc bias voltage, and obtain excellent agreement for temperatures in the range 235–295 K. This demonstrated agreement implies that full dielectric tuning can be expected in these ferroelectric thin films on nanosecond time scales, and also demonstrates that detrimental high-frequency nonlinear effects in device structures can be accurately predicted based on dc biased measurements.