On-Chip Integrated Distributed Amplifier and Antenna Systems in SiGe BiCMOS for Ultra-Large-Bandwidth Transmitters (DAAB-Tx)

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Project DAAB was widely successful in the design of ultra-wideband integrated antenna and amplifier receivers over a bandwidth in excess of 100 GHz: the state of the art has been improved in all the key areas. The proposed project DAAB-Tx complements the results of DAAB towards the demonstration of the first wireless transmission over a bandwidth of more than 100 GHz. The project activities will be structured around several approaches: (1) integrate a wideband distributed power amplifier with a broadband antenna; (2) drive an array of antennas centered at adjacent frequencies; (3) drive an array of antennas with distributed active dividers. The distributed multi-antenna approaches can offer several remarkable advantages. (a) The bandwidth requirements of each antenna are relaxed. (b) The overall transmitted power is distributed across the spectrum and each associated amplifier can be optimized to deliver only its share. (c) Recombination of power after amplification is pushed to the air with minimal losses.Regarding the antenna design for single-antenna solutions, emphasis will be given to ultra-broadband antennas. The investigation of broadband artificial magnetic conductors (AMC) will be addressed: this alternative design eliminates the main disadvantage of a standard reflector, which is the limited bandwidth due to the fixed distance of a quarter of the wavelength. Therefore this approach uses the properties of the silicon to focus the radiated energy. For multi-antenna approaches, several antennas at adjacent frequency bands will be designed to work in close proximity to the distributed amplifier and active dividers, e.g. fractal bowties. With multiple antennas on a single chip, coupling between antenna elements and between antennas and electronics will become a very important issue, which will be addressed. To partly mitigate these effects, antennas with different polarization will be considered.The goal of the amplifier design work is to maximize the output power over the broadest possible bandwidth. Distributed topologies will be studied, as they are well fit to drive antennas over a very broad bandwidth, and optimized for maximum output power. In a novel approach, the tapered travelling-wave amplifier will be enhanced with stacked-transistor gain cells, which are suitable for higher-output voltage at a given maximum current. In order to further maximize the output power, the number of elements in the distributed structure will be increased with 2-dimensional travelling-wave amplifiers. Both structures will be adapted to single- and multi-antenna solutions by replacing the output synthetic transmission line with an array of antennas. Finally, active broadband dividers will be implemented by merging the input lines of two tapered travelling-wave amplifiers and used to drive multiple antennas centered at adjacent frequencies.