| With the rapid development of the wireless communication technology, the market arises great demand for radio frequency (RF) integrated circuits (ICs). Because of the mature technology, low cost and low power consumption, CMOS RFIC becomes the development trend of RF ICs. Voltage-Controlled Oscillator (VCO) holds a very important position in RF ICs, which is the main part of PLL, Clock Recovery Circuit and Frequency Synthesizer. So, Design high performance VCO has a great significance in improve the performance of the Communication System.First, in this thesis, I briefly introduce the fundamental theory of oscillators and oscillator's class, Compare the advantages and disadvantages of them. Compare the performances and characteristics of different kinds of "negative-Gm" oscillators, and analyze the concept of phase noise introduce the main phase noise theories nowadays.In CMOS technology, the fully integrated inductors with high quality factor is the key of a LC-VCO design, the structures and realizations of on-chip spiral inductor in CMOS technology, and the physical reasons which affect the Q-factor are analyzed. And I also introduce the realization in CMOS technology of varactors, which is another passive component in LC-VCO. The tradeoff between Q-factor and tuning range of varactor is demonstrated.Finally, I analyze the design methodology and flow of a LC-VCO which has a wide tuning range completely. Finish the whole design through tradeoff the phase noise, power consumption, tuning range and so on. At the same time, simulate the design. The simulation shows that the design achieve the requirement, has a good performance.Consider with the actual use, I improved the structure of this circuit. I use a Band-Switch to control the tuning range, divide it into four regions each has a tuning rang of a quarter of the primary. It can improve the performance of the VCO circuit, and make it more useable. At last, finish the lay-out and the post-simulation of the design. |
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