Self-bias On-chip Nanoferrite Circulator for CMOS Integration: Design, Fabrication and Measurement

The overcrowded wireless spectrum and the rapidly increasing need for Giga-bit per second downlink data rate form the driving force of microwave frequency front-end module research and development. The unlicensed 57-63 GHz frequency range is of great importance to the realization of such high speed access point. Modern ferrite microwave devices that are smaller, faster and consume much less power than their active counterparts have been scaled down with help from metamaterials and nanofabrication. Comparing to the traditional, bulky radio frequency ferrite device, their microwave cousins are promising candidates for a critical role in the aforementioned high speed applications. This thesis presents a complete design, simulation, fabrication and testing of a self-bias, magnetic circulator operating at 60GHz. It features 15dB isolation, 2mm by 2mm size and potential of further integration with CMOS or GaN technology. Simulated and measured results are presented and analyzed together with a detailed fabrication recipe and step by step microscopic photos. This device can be used in applications such as integrated transceiver, phased array radar system, air traffic control and navigation.