Microstrip delay line phase shifter by actuating integrated ground plane membranes

Abstract

The design, simulation, fabrication, measurement and performance of a V-band microstrip delay line phase shifter using electrostatically actuated integrated micro-machined ground plane membranes are presented. The microstrip line is etched on an RFIC-friendly silicon substrate. The membrane is made of aluminium micro-ribbons and is fabricated on the ground plane side of the silicon substrate. The actuation of the ribbons away from the transmission line introduces an air gap between the radio-frequency (RF) substrate and the ground plane. By controlling the air gap thickness, a controllable phase shift in the transmission line is obtained. Each micro-ribbon measures 3.20 mm in length, 20 mm in width and 1 mm in thickness. A measured phase shift of 418 at 50 GHz was achieved with an actuation voltage of 120 V. The fabrication process added a 20 mm initial air gap between the micro-ribbons and RF substrate, increasing the required actuation voltage for a given phase shift. The simulated phase shift results agree well with the measurements.

A reconfigurable defected microstrip structure for applications in phase shifter

“…Compared to the DGS based phase shifters [1][2][3][4], the proposed phase shifters employing RDMS have a number of advantages. It has a higher phase shift compared to the designs in [1][2][3] and a lower insertion loss than those in [2,4].…”

“…Recently, there has been an increasing interest in phase shifters using defected ground plane structure (DGS) [1][2][3][4]. The phase shifter in [1] employed a DGS as a termination load, which increased the phase shift range by 80 • compared with the same structure using a conventional load.…”

“…By actuating the membranes using high voltages, the space between the transmission line and ground plane were tuned and the line capacitance changed, thus producing a phase shift. Subsequently, this phase shifter was improved by replacing the membranes with flexible microribbons to obtain a lower actuating voltage [3]. In [4], ground plane reconfiguration was realized to introduce phase shift by employing a metallized polidimethylsiloxane (PDMS) elastomeric ground plane.…”

A compact phase-shifting unit for phased array antennas

“…Therefore, the cost, size, and integration method of the phase shifters are of great concerns [2]. Except for the most popular ferrite phase shifters and diode phase shifters, there has been an increasing interest in phase shifters based on defected microstrip structure (DGS) [3][4][5][6][7]. However, for most of the designs, multi-layer structures and microelectromechanical systems (MEMS) are used, resulting in the high costs, high fabrication complexity, and difficulties in integrating with microstrip systems.…”

Controllable microstrip phase shifter using actuating membrane ground plane

“…Similarly, microstrip line phase shifters using membrane actuated ground plane was conceived [4], in which by moving the ground plane spacing from microstrip transmission line a differential phase shift was achieved. However, in the present endeavor, the performance of microstrip transmission line controllable phase shifter is investigated (i) by varying the uniform air gap thickness beneath the glass substrate, and (ii) implementing an air gap using the membrane.…”