MEMS variable-capacitor phase shifters part II: Reflection-type phase shifters

Abstract

A novel design procedure for reflection-type phase shifters using capacitive devices is developed. Using this approach, a phase shifter for operation at 26.5 GHz is developed using MEMS variable capacitors reported in Part I of this article. A design optimization procedure is discussed. Design of a CPW hybrid at 26.5 GHz (as needed for this phase shifter) is also discussed. Experimental results validate the design procedure and yield a phase shift of 179.30°at 26.5 GHz.

MEMS variable-capacitor phase shifters part I: Loaded-line phase shifter

“…The input/output line characteristic impedance is chosen to be 100⍀ for direct connection to the slot antenna with the same input impedance. Formulas (7), (9), and (10) are used to arrive at the initial circuit parameters. These initial values are optimized in a circuit simulator in order to compensate the series resistance of the two capacitors.…”

“…The design and characterization of these phase shifters are reported in detail in this article. A companion article [7] will discuss the application of MEMS variable capacitors to the design of reflectiontype phase shifters.…”