Distributed MEMS analog phase shifter with enhanced tuning

The design, fabrication, and measurement of a tunable microwave phase shifter is described. The phase shifter combines two techniques: a distributed capacitance transmission line phase shifter, and a large tuning range radio frequency (RF) microelectromechanical system (MEMS) capacitor. The resulting device is a large bandwidth, continuously tunable, low-loss phase shifter, with state-of-the-art performance. Measurements indicate analog tuning of 170deg phase shift per dB loss is possible at 40 GHz, with a 538deg phase shift per centimeter. The structure is realized with high-Q MEMS varactors, capable of tuning Cmax/Cmin= 3.4. To our knowledge, this presents the lowest loss analog millimeter wave phase shifter performance to date