A Si MMIC compatible ferroelectric varactor shunt switch for microwave applications

This letter describes a ferroelectric thin-film based varactor shunt switch, for microwave and millimeterwave switching applications. Our implementation is based on a coplanar waveguide transmission line shunted by a ferroelectric varactor. The concept of switching ON and OFF is based on the dielectric tunability of the ferroelectric barium strontium titanium oxide (BST) thin-films. From experimental verification, the isolation of a switch with a varactor area of 75 mu m(2) was approximately 20 dB at 35 GHz and the insertion loss was below 4.5 dB up to 35 GHz. This letter addresses the design and experimental verification of the first ferroelectric varactor shunt switch with an Si monolithic microwave integrated circuit compatible process.