使用 0.18um CMOS 實現多頻帶之電壓控制環型振盪器

Abstract

本論文提出一個具有多頻帶的電壓控制環型振盪器 (Voltage-Controlled Ring Oscillator)。 一般具有多重路徑 (multiple-pass) 的環型振盪器， 大都是設計在提升振盪器的振盪頻率。 本論文利用多重路徑觀念, 設計出可以使其振盪頻率減慢的連接方式。 然後再利用 NMOS 作為開關電路， 將加快振盪頻率的多重路徑振盪器電路與減慢振盪頻率的多重路徑振盪器電路結合在一起。 由 NMOS 開關的切換去改變電路的連接路徑，如此可得到更大的頻率調整範圍之振盪電路。 由此設計, 每一差動放大級及所需開關共需使用 12 顆 MOS 電晶體， 其中有 8 顆 是 NMOS 及 4 顆是 PMOS。 本論文並以台灣積體電路製造股份有限公司 (TSMC) 0.18 $\mu m$ 1P6M CMOS 製程來模擬一含九級差動放大的電壓控制環型振盪器。 由後端模擬結果 (Post-Sim) 顯示， 在工作電壓為 1.8V 下， 此振盪器的消耗功率為 91.4 mW, 在中心頻率為2GHz, 偏移頻率1MHz情況下, 相位雜訊為 -115.8 dBc/Hz, 振盪頻率範圍可達到 0.32GHz-1.8GHz, 其輸出的峰對峰 (peak-to-peak) 振幅最小值可至 1.67V。

This thesis presents a multi-band voltage-controlled ring oscillator via the multiple-pass connection, resulting in a wide range of oscillation frequency. Most multiple-pass ring oscillators are designed to increase the oscillation frequency. In this thesis, we also exploit the concept of multiple-pass to design a multiple-pass ring oscillator which can decrease the oscillation frequency. A connection is designed via the NMOS switch to combine together the two circuits all via the concept of multiple-pass such that a wider range of oscillation frequency can be obtained. Hence, we obtain a voltage-controlled oscillator with two frequency bands which can be easily controlled by the on/off of the NMOS switches. We design a nine-stage ring oscillator; each stage consists of twelve MOS transistors including eight NMOS transistors and four PMOS transistors. This oscillator is simulated using 0.18 $\mu m,$ 1P6M CMOS technology provided by Taiwan Semi-Conductor Manufacturing Company. The post simulation of the design oscillator, under the supply voltage of 1.8 V, shows that the required power is 91.4 mw, the phase noise is -115.8 dBc/Hz at a 1-MHz offset from a 2-GHz center frequency, the frequency tuning range is from 0.32GHz to 1.8GHz, and the minimum peak-to-peak output swing is 1.67V.