Calibrated Low-Loss Phase Shifter with Negative Resistance Circuit and Sigma-Delta PLL for Multiple-Antenna Receivers
Introduction Variable Phase Shifters are used in many applications such as adaptive smart-antenna receivers. In adaptive antenna receivers, antenna paths are linearly combined in an RF stage after being adjusted in both amplitude and phase. Variable-gain low-noise amplifiers and variable phase shifters are used to adjust the amplitude and phase of each received signal, respectively. Due to a lower noise figure and zero dc power dissipation, passive phase shifters are more attractive than their active counterparts. It is clear that precision low-cost phase shifting circuits are a critical component of future wireless devices. Efforts so far have been characterized by poor performance in terms of high noise figures, high signal losses, and very poor sensitivity to the process, voltage, and temperature (PVT) variations that characterize modem integrated circuit technology Technology description Researchers at the University of Washington have developed a way to compensate a reflective-type phase shifter using negative resistance. This invention will enable the fabrication of highperformance low-cost radios in the near future. Specifically, an active negative resistance function is added to a passive phase-shifting network to reduce the signal losses. Since the losses are decreased, the potential noise added by the active devices is mitigated and good noise figure is achieved. A replica technique is used to provide insensitivity to PVT variations. Finally, a sigmadelta data converter is used to provide a simpler means of phase control than has been used previously and this also reduces the cost of the phase-shifting topology. Business opportunity The overall wireless device market is expected to increase to $24.5 billion in 2009 growing at a 13.1% CAGR. Intellectual Property Position This technology is available for licensing. Related Publication(s)
Zarei H, Allstot DJ, A Low-Loss Phase Shifter in 180nm CMOS for Multiple-Antenna Receivers, 2004 IEEE International Solid-State Circuits Conference.
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