RF Performance Evaluation of Ferroelectric Varactor Shunt Switches

摘要

This paper addresses experimental RF performance evaluation, and electrical parameter extraction of different size ferroelectric varactor shunt switches. The ferroelectric varactor shunt switch operation is based on nonlinear dielectric tunability of a Ba0.(6)Sr0.(4) TiO3 (BST) thin-film sandwiched between two metal layers in the parallel plate configuration. Coplanar waveguide implementation of the varactor shunt switch results in a high speed RF switch, with a simple two-metal layer Si MMIC compatible process on high resistivity Si substrates. Experimental RF performance of the switches show low insertion loss for smaller area devices, with good isolation for larger area devices. To optimize the device design, RF performance of multiple devices were tested, and electrical parameters were extracted. The capacitance of the varactor shunt switches tested were tunable more than 4:1 for bias voltages below 12 V. The switching speed of the devices tested was approximately 43 ns based on the step response measurements.