Performance of a K-Band Voltage-Controlled Lange Coupler Using a Ferroelectric Tunable Microstrip Configuration
Subramanyam, G., F.A. Miranda, F. Van Keuls, R.R. Romanofsky, C.L. Canedy, S. Aggarwal, T. Venkatesan, Ramamoorthy Ramesh
We report for the first time on the performance of a Au/Ba0.6Sr0.4TiO3 (BSTO)/MgO two-layered microstrip voltage-controlled Lange coupler (VCLC) designed for Ku- and K-band frequencies at room temperature. Tight coupling of 3 dB or higher was obtained over a frequency range of 14–19 GHz. At K-band frequencies, the coupling was voltage-controllable using the nonlinear dc electric field dependence of the relative dielectric constant of BSTO (εrBSTo)- The coupling level was improved from —11.6 to —3.7 dB at 20 GHz with an applied dc electric field of 16 kV/cm. The introduction of the ferroelectric tuning layer enhances the bandwidth of the VCLC in comparison with a Lange coupler with no ferroelectric layer. This work demonstrates another advantageous application for ferroelectric thin films in passive microwave components. © 2000, IEEE. All rights reserved.
IEEE Microwave and Guided Wave Letters
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