| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 96 === In the last few years, the explosive development in wireless communication has resulted in increasing demands for transceivers operating in multi-standard and multi-band communication systems. The emerging wireless standards have pushed researchers to look for low phase noise and wideband VCO capable of operating at several frequency bands. Therefore, to design a wide tuning range VCO with low phase noise is challenging in CMOS technology.
The goal of the thesis is to design and implement wideband VCOs in microwave and millimeter-wave region using CMOS technology. This research focuses on the LC-VCO with switched coupled inductors. The thesis can be divided into three parts. The first part introduces the application of oscillators and discusses the theory of LC-VCO. In the next part, two wideband VCO designs are presented. The first one is a NMOS-only cross-coupled VCO using the switched coupled inductor with terminated capacitor. However, the chip is just a function work due to underestimating the loss of the switches. The VCO only has the oscillation frequency from 8.42 GHz to 11.24 GHz. The other one is also designed for wide tuning range using complementary cross-coupled topology but in high frequency. The VCO operates from 31.86 GHz to 35.26 GHz with phase noise about -89 dBc/Hz at 1 MHz.
At the last part, a wideband VCO with 88.6% tuning range is demonstrated. The VCO modifies the drawback in the first chip with accurately estimating the totally loss. In this circuit, a novel switched coupled and varactor-tuned inductor is used. This VCO demonstrates a continues tuning range from 7.82 GHz to 20.27 GHz. The measured phase noise are -106.6 dBc/Hz when center frequency is 7.82 GHz at 1 MHz offset frequency and -85.11 dBc/Hz when center frequency is 20.27 GHz at 1 MHz offset frequency. The measured Vdd is 1.3 V with a core current 6 mA, and the chip size is 0.325mm2.
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