Global ETD Search

31	Multiple antenna downlink: feedback reduction, interference suppression and relay transmission Tang, Taiwen 28 August 2008 (has links) Not available / text MIMO systems Antennas (Electronics) Radio--Transmitter-receivers Radio--Interference Feedback control systems
32	A wide dynamic range high-q high-frequency bandpass filter with an automatic quality factor tuning scheme Kumar, Ajay 09 January 2009 (has links) An 80 MHz bandpass filter with a tunable quality factor of 16∼44 using an improved transconductor circuit is presented. A noise optimized biquad structure for high-Q, high- frequency bandpass filter is proposed. The quality factor of the filter is tuned using a new quality factor locked loop algorithm. It was shown that a second-order quality factor locked loop is necessary and sufficient to tune the quality factor of a bandpass filter with zero steady state error. The accuracy, mismatch, and sensitivty analysis of the new tuning scheme was performed and analyzed. Based on the proposed noise optimized filter structure and new quality factor tuning scheme, a biquad filter was designed and fabricated in 0.25 μm BiCMOS process. The measured results show that the biquad filter achieves a SNR of 45 dB at IMD of 40 dB. The P-1dB compression point and IIP3 of the filter are -10 dBm and -2.68 dBm, respectively. The proposed biquad filter and quality factor tuning scheme consumes 58mW and 13 mW of power at 3.3 V supply. Tuning GM-C Filter Analog filter Continuous time MLL QLL Quality factor Electric filters, Bandpass Radio Transmitter-receivers Wireless communication systems
33	Operating voltage constraints and dynamic range in advanced silicon-germanium HBTs for high-frequency transceivers Grens, Curtis Morrow 04 May 2009 (has links) This work investigates the fundamental device limits related to operational voltage constraints and linearity in state-of-the-art silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) in order to support the design of robust next-generation high-frequency transceivers. This objective requires a broad understanding of how much "usable" voltage exists compared to conventionally defined breakdown voltage specifications, so the role of avalanche-induced current-crowding (or "pinch-in") effects on transistor performance and reliability are carefully studied. Also, the effects of intermodulation distortion are examined at the transistor-level for new and better understanding of the limits and trade-offs associated with achieving enhanced dynamic range and linearity performance on existing and future SiGe HBT technology platforms. Based on these investigations, circuits designed for superior dynamic range performance are presented. Pinch-in Reliability Safe-Operating Area (SOA) Silicon germanium Dynamic range Intermodulation distortion Linearity Breakdown voltage Avalanche multiplication Bipolar transistors Heterojunctions Bipolar transistors Radio Transmitter-receivers Silicon compounds Germanium compounds

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