Mixers and Multifunctional MMICs for Millimeter-Wave Applications

Doktorsavhandling, 2008

This thesis treats the design and characterization of different mixer and multifunctional monolithic microwave integrated circuits (MMICs) in GaAs pHEMT and mHEMT technologies. The MMICs operate at the V (50 – 75 GHz) and G (140 – 220 GHz) bands and several of them demonstrate state-of-the-art performance, level of integration, novel topologies, and/or novel functionality. The multifunctional designs include V-band MMICs with various levels of integration. 60 GHz single-chip front-end transmitter and receiver MMICs with an on-chip multiply-by-eight LO chain are demonstrated together with a 60 GHz sub-harmonically pumped receiver MMIC. These are generic designs but are particularly suited for wireless transfer of high data rate signals (several Gbps). A 53 GHz single-chip radiometer front-end is also presented with 7 GHz of IF bandwidth and an integrated multiply-by-four LO chain. Furthermore, a 220 GHz single-chip receiver MMIC with an on-chip antenna is demonstrated. This MMIC is mounted on a silicon substrate lens which focuses the radiation to the on-chip antenna through an opening in the backside metallization of the MMIC. The noise figure is as low as 8.4 dB (1750 K) at 220 GHz including the losses in the lens and the antenna. The major part of this work deals with the analysis and design of different MMIC mixers. Several different mixer topologies exist depending on application and the choice of mixer often determines the topology and performance of the overall millimeter-wave system. Different mixer topologies are discussed and exemplified by several MMIC designs, starting with single-ended G-band resistive and drain mixers. Image reject mixers (IRMs) are discussed and the classical IRM theory found in the literature is enhanced by applying wave analysis. An IRM is presented with a state-of-the-art 30 dB of image rejection ratio in the 60 GHz band. Sub-harmonically pumped mixers are also analyzed using wave analysis and a novel sub-harmonically pumped mixer is demonstrated, utilizing only a quarter of the nominal LO frequency compared to a fundamentally pumped mixer. Mixer topologies for enhanced LO-to-RF isolation are presented and two mixer MMICs are demonstrated as well as a 60 GHz double-balanced Gilbert mixer with integrated RF, LO, and IF baluns.