Monolithic Phase Shifter Based on Mechanically Tunable Saw Delay Line

This paper presents results of mechanically controlling the phase velocity of surface acoustic waves (SAW) and the application to monolithic phase shifters operating at 0.1~10 GHz. A phase sensitivity of 2deg/V and sensitivity of the phase velocity (Deltav/v) of 41times10^-6 /V have been measured for devices operating at 2.45 GHz. This is 2 orders of magnitude larger than existing SAW-based monolithic phase shifters. The acoustic wavelength being 10.000 times smaller than the free space equivalent together with the large sensitivity lead to a 50~500 times reduced device area compared to existing phase shifters.