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Design methodology for image-reject low-power receivers for wireless communications

Entwurfsmethodologie für leistungsarme Empfänger mit Spiegelfrequenzunterdrückung für drahtlose Kommunikation
: Carrera, A.
: Gerhäuser, H.


Stuttgart: Fraunhofer IRB Verlag, 2007, 270 pp.
Zugl.: Erlangen-Nürnberg, Univ., Diss., 2007
ISBN: 3-8167-7455-5
ISBN: 978-3-8167-7455-6
URN: urn:nbn:de:bvb:29-opus-7330
Fraunhofer IIS ()
Image-reject mixer; mixer; CMOS RF; integrated circuit design; low-power design; receiver architecture; image-reject receiver; dual-receiver; polyphase filter; CMOS layout technique; weaver architecture; hartley architecture; wireless communication

All receivers for wireless communications based on frequency down-conversion have to deal with the image band. The folding of image energy onto the carrier after down-conversion can significantly corrupt the signal-to-noise ratio of a receiver. Image-reject mixers remove the image energy providing performance in terms of gain, linearity and noise similar to a conventional mixer posing a better alternative to external/integrated image-reject band-pass filters. Additionally, IR mixers enable both non-concurrent and concurrent reception of two bands with a unique receiver, being the key component of dual receivers. In the literature, the design of IR mixers is focused on maximizing the image-rejection ratio (IRR). At present the IRR achievable with an IR mixer is approximately in the same order as the degree of rejection attained by an external band-pass filter. However, the stumbling block that prevents the widespread use of IR mixers as a feasible integrated alternative to external band-pass filtering is the higher power dissipation compared to a conventional mixer. The lack of a complete analysis in terms of IR receivers and their requirements in terms of IR on one side, and the lack of a design approach that optimizes the required IR and a minimal power consumption striking a balance between these two somewhat opposed parameters on the other side, have motivated this research work.
This work contributes in the following three main topics: IR receiver architectures, CMOS mixers for operation in IR mixers and low-power CMOS IR mixers. First, IR requirements of modern receiver architectures and possible IR topologies that fit into these receivers are studied. Based on this analysis, two novel IR dual receiver architectures are proposed, which give a power-optimized solution to the most challenging case of broadband dual receivers for positioning and navigation systems. Second, the mixer topologies best suited for integration within an IR topology are thoroughly studied in terms of the impact of each section of the mixer on the performance metrics of the mixer. Relying on this study, three mixer optimization cases are researched: multi-band operation, low-voltage low-power operation and DC-o set/icker noise. All optimizations are backed up by measured data on four prototypes that show excellent matching to simulation. Third, a novel design methodology for low-power IR mixers is developed to address the lack of a power-aware optimization of IR mixers. This approach focuses on two complementary optimization aspects: a statistical optimization and a structural optimization. The design framework chosen is an indirect-conversion receiver for Industrial Scientific Medical at 433 MHz (ISM-433) for short-range telemetry, where both moderate/large IRR and low power dissipation are required, imposing the most challenging environment for CMOS IR mixer design. The Weaver IR mixer and offset-free Hartley IR mixer implemented show very good agreement between simulated and measured data, and validate the proposed methodology imposing an important headway to the state of the art in terms of power-optimized IRmixers.