Prof. Darrin J. Young
EECS Dept., Case School of Engineering
Power-efficient wireless transceivers are critical for low-power wireless applications such as space communications. Current transceiver designs employ a single antenna and rely on using duplexers to isolate the transmitter and receiver signal paths. However, these components exhibit a large insertion loss typically around 3 dB resulting in a significant power dissipation at the transmitter output. An innovative wireless transceiver architecture is proposed for future space communications in which two miniature patch antennas are employed to separate the transmitter and receiver paths, thus eliminating the need of lossy duplexers. Each antenna is designed to function in the corresponding transmit and receive band. Patch antenna typically exhibits a narrow bandwidth. Thus, an electrical tuning capability is necessary to cover the required frequency range. Low-loss (high-Q) tuning devices which are insensitive to RF signals and can sustain a large voltage swing are crucial for this application. Conventional PN-junction-based varactor diodes cannot fulfill the requirements. MEMS tunable capacitors, however, can achieve all the stringent performance requirements, thus critical for implementing the proposed low power system. In this presentation, a MEMS touch-mode RF tunable capacitor design and fabrication process will be illustrated. The device is estimated to achieve a nominal capacitance value of 2 pF with a high quality factor well above 300 at 1 GHz and a tuning range over 100 % under 10 V. Its tuning application to a prototype GHz patch antenna will also be presented.