Novel Approaches in RF/Analog CMOS Spectrum Sensing and Its Applications

Real time spectrum sensing refers to searching for possible signals at a specific time and location, which is applicable to cognitive radio (CR) for primary signal detection and ultra-wideband (UWB) radio for interferer detection. There are several approaches for spectrum sensing. Choosing a proper method for spectrum sensing necessitates evaluating several trade-offs among sensing time, accuracy, power consumption and simplicity of implementation. In this dissertation several approaches for spectrum sensing along with the applications to CR and UWB receivers are presented. A novel simple spectrum sensing technique for detecting weak primary signals with negative signal-to-noise ratio (SNR) is proposed, which is called quasi-cyclostationary feature detection (QCFD) technique. Moreover, a simple, reliable, and fast real-time spectrum sensing technique based on phasers, which are dispersive delay structures (DDSs), is proposed. Lastly, a UWB receiver robust to the narrowband (NB) blockers, in the vicinity of UWB frequency, is presented. To increase the robustness of the UWB receiver towards interferers, a dynamic blocker detector, utilizing a phaser-based real time spectrum sensing technique, is employed. The proposed spectrum sensing methods provide the best solutions for the intended applications, considering the trade-offs, compared to the state-of-the-art CMOS spectrum sensors