AbstractA Swiss university offers a waveguide-mounted radio frequency (RF) MEMS phase shifter providing a large controllable variable phase shift with very low dissipated power and high levels of RF power handling for frequencies in the millimeter-wave range. The device allows for the realization of gigabit-rate adaptive communication systems, imaging, sensing and radar systems, phased antenna arrays. License agreement, joint further development and/or testing of new applications are sought.
DetailsAt frequencies where the size of MEMS (Microelectromechanical systems), which actuate electrically conductive functional elements, matches approximately the wavelength of the RF signal, a Swiss university developed efficient, low signal loss and cheap devices such as a variable power divider and tunable phase shifters, allowing for the realization of adaptive communication systems at millimeterwave frequencies.
Phase shifters are two-port devices that modify the transmission phase of an RF signal and provide signal control. Millimeter-wave phase shifters (30 -300 GHz) with reconfigurable characteristics are of significant importance due to the potential of integration in adaptive high data-rate communication systems like fourth-generation cellular backhaul, sensing and imaging systems. The vast majority of existing phase shifter devices is typically discrete and based on switched transmission lines using RF MEMS. Alternatively, the material properties of ferroelectrics and ferrites are tuned by external E-field (electric E-field) or H-field (magnetic H-field), resulting in a phase shifting operation. The first approach is mainly limited by excessive dissipation loss and low power handling of the transmission media. In the second analog approach, devices are of large form factor and show high dissipation at high frequencies.
Fig. 1: Model of the analog transmission-type phase shifter, showing the tunable waveguide resonator (3 protruding studs and 2 notches) and the MEMS chip
The presented invention introduces a novel concept for a continuously variable millimeter-wave phase shifter (30 -200 GHz) with significantly improved RF performance.
The proposed device consists of a structured ridge waveguide resonator and a new class of a micro mirror MEMS as a tuning element. The proposed MEMS chip is placed beneath the waveguide ridge (Fig. 1). It consists of two sets of conductive rigid fingers that rotate in an anti-parallel fashion. Electrostatic comb drive actuators allows for large out of plane deflections with low DC power consumption.
This sort of mechanical movement realizes a distributed variable capacitive shunt load which in turn results in a large variable controllable phase shift (Fig. 2). Integration of the MEMS chip directly into an air-filled metallic waveguide results in very low dissipation loss and high RF power handling. Besides the phase shifter device the proposed concept can be further applied to numerous RF components and opens new possibilities for the design of efficient, adaptive millimeter-wave systems.
Fig. 2. Continuous phase shifter performance (1) for various MEMS deflection angles shown at 95 GHz, the transmission phase variation is about 1100 (2), insertion loss is better than 0.3 dB (< 6.6 %) and input reflection is better than -15 dB.
Note: Some websites do not show figure 2. Please make an Expression of Interest and request for the figure.
One could think of the following applications areas: Ultra-high data rate adaptive communication systems, imaging, sensing and radar systems (automotive, aerospace), phased antenna arrays and tunable filters, resonators, signal modulators
- Large variable phase shift
- Very low signal loss
- High RF-power handling
- Low DC-power consumption (green IT)
- High repeatability, reliability and control
- Efficient manufacturing process