Abstract-This paper presents a novel frequency-offset technique to enhance operating range of frequency synthesizers for long-term evolution-advanced and cognitive-radio applications. Conventional wideband frequency synthesizers typically have complex architectures, such as multiple phase-locked loops (PLLs), multiple voltage-controlled oscillators, and multiple mixers, to increase operating range. These complex architectures have high cost and power consumption. In this study, the proposed technique substantially increases the operating range of the frequency synthesizer by using only a single PLL to simultaneously lock two mixing oscillators. The presented frequency synthesizer is implemented using 0.18-m CMOS technology. Performance tests demonstrate that the frequency synthesizer achieves a very wide operating frequency range from 50 MHz to 4.8 GHz with a phase noise lower than 100 dBc/Hz at a frequency offset of 100 kHz. The period of stability for a switching frequency of 40 MHz is shorter than 40 s. Index Terms-Cognitive radio (CR), long-term evolution-advanced (LTE-A), phase-locked loop (PLL), wideband frequency synthesizer, wideband voltage-controlled oscillator (VCO).

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Thin-beam directional X'tallization (TDX) is a low-temperature-substrate compatible crystallization method that can form directionally solidified poly-si films directly on glass substrates. Without using a mask, extremely long uniformly-spaced poly-Si grains can be formed by TDX. In this paper, we have investigated the influence of laser energy and scan pitch on the properties of the resulting poly-Si films. Grain size and surface morphology of TDX-processed poly-Si films were observed by SEM and AFM. The AFM results demonstrate that, due to the lateral growth phenomenon, TDX poly-Si films are much smoother than films produced by the current industry standard method, Excimer Laser Annealing (ELA). The breakdown of the TDX method is also discussed in this paper. When the laser scan pitch is larger than the lateral growth length that is characteristic of a given poly-Si film and beam property combination, a discontinuous poly-Si film is formed with vertical protrusions and grain boundaries occurring perpendicular to the scan direction. Poly-Si films with vertical protrusions and grain boundaries perpendicular to the direction of current flow will degrade the resulting thin-film transistor (TFT) performance.