TUNABLE MICROWAVE INTEGRATED CIRCUITS USING BST THIN FILM CAPACITORS WITH DEVICE STRUCTURE OPTIMIZATION

ABSTRACT

The mechanism of losses in barium strontium titanate (BST) thin film capacitors is analyzed at the device level. A geometry dependent RF model is used to minimize the electrode loss. Results show the capacitors' RF quality factors can be further optimized through geometry. A tunable filter and a phase shifter are demonstrated using these design techniques. Successful integration of the BST process with GaN HEMT circuits in the form of a 5 GHz GaN HEMT oscillator is presented. BST thin film technology is shown to be useful for the design of frequency agile circuits and reduction of layout areas in various microwave applications.

Keywords:

• Barium strontium titanate
• BST
• tunable filter
• MMIC