The feasibility of fabricating a YBCO based passive microwave device with GaAs ICs on a single GaAs wafer by in-situ Pulsed Laser Deposition (PLD), conventional photolithographic patterning and metalization techniques will be developed. The superconducting properties of the YBCO films to select the best buffer film material and film deposition process will be evaluated in order to obtain high quality superconductor films. A simple superconductor stripline filter will be integrated with a GaAs low noise amplifier, and the device performance evaluated. The ability to fabricate HTSC films on GaAs substrates opens up a very rich field of opportunity for many superconducting film technologies.