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標題: Chip Design of Clock Generation and Frequency Synthesis for Optical Access Network & Radio over Fiber System(I)
作者: 楊清淵
關鍵字: OFDM
電子電機工程類, 電信工程
optical receiver
radio over fiber
phase-locked loop
clock generator
RFfrequency synthesizer
摘要: The goal of the research project described in this work is to realize fully integrated clockgeneration and RF frequency synthesis circuits to be used in a low-cost OFDM optical andradio-over-fiber (RoF) receiver. This work is devoted to the subject of CMOS phase-lockedloop (PLL) design for future wideband 10-Gb/s optical applications. The PLL is used togenerate a clock signal of the 6-bit ADC with sampling approaching 4 GS/s and 500-MHzclock for digital blocks, and provide LO signals of 60-GHz RF front ends. There are twomain parts in this work: a high-resolution -modulated PLL for 4-GHz clock generationand a high-frequency PLL frequency synthesizer for 60-GHz RF. Since a frequency andphase offset exists in the received data and the local clock signal, frequency-offsetcancellation is required. A 16-bit  modulation technique is introduced into the PLL. In thisway the PLL can perform high resolution function for frequency tuning and phase alignment.Constructed by digital technology, the  modulator is easy to be integrated andimplemented. The calibrated range in this work can achieve into more than 20 ppm. In60-GHz RF receiver, the LO frequency planning is dependent on the front-end structure andthe LO circuit is also designed by the PLL. Employing a two-stage heterodyne architecturecan require a 48-GHz LO as the first stage and a 12-GHz LO in quadrature as the secondstage. In the PLLs, an oscillator based on the resonance of an LC-tank is the only one thatgives a sufficiently high output frequency with a low noise. The fully integrated VCO withspiral inductors has been implemented in standard CMOS processes. The high-frequencybuilding block is combined together with the other parts of a PLL, such as the divider, thephase detector, the charge pump, and the low-pass filter, in a charge pump PLL frequencysynthesizer that aims at the high-performance applications. In addition, since the VCO of the60GHz RF PLL synthesizer is based on narrow-band regimes, the narrow-band analogfrequency doubler may be more suitable for the first-stage LO to reduce power consumption,increase maximum operation frequency and remove the high-order harmonics. Moreover,introducing the frequency doubling regime in the synthesizer can mitigate the speedlimitation of the VCO and the divider. In response to these designs, there is a continuedsearch for architectures and circuit techniques enabling a monolithic solution to meet ourspecifications with reasonable chip area and power dissipation.
此研究計畫的目的是要設計一個完全積體化的時脈產生和頻率合成電路,可以使用於低成本的OFDM 光纖和光載射頻接收器的應用上面。研究主軸是以CMOS 技術設計鎖相迴路電路,應用於10Gb/s 光纖系統。我們利用鎖相迴路實現4GHz 時脈信號產生,提供給六位元類比數位轉換器為取樣信號和500MHz 數位電路的時脈,以及提供60GHz 射頻前端電路的本地振盪信號。電路研究重點主要分兩部份:高解析度積分三角調變鎖相迴路之時脈產生設計和60GHz 射頻前端本地振盪之頻率合成設計。首先,由於接收的資料率和本地的時脈頻率會有誤差發生,頻率誤差和相位偏移的校正技術是需要的。我們將16 位元三角積分調變技術引進鎖相迴路,使其可達高解析度的頻率和相位調整功能,由於是數位電路,因而易於整合和實現,其校正範圍可達20ppm 以上。其次,對於60GHz 射頻接收器,本地振盪頻率決定於所採用的射頻前端架構,本地振盪電路也是都由鎖相迴路設計。本計畫採用二級外差式架構,需要本地振盪頻率是48GHz 為第一級和12GHz 正交為第二級。就鎖相迴路而言,其振盪器之設計是以電感—電容共振為架構,它是唯一具有高頻率且低雜訊的線路。這種以標準金氧半製程設計了高頻電壓控制振盪器,它是採用螺線型電感設計。結合鎖相迴路的其它元件,如除頻器、相位比較器、充電泵以及低通濾波器,設計出一個充電泵鎖相迴路頻率合成器,目標是要達到高效能上的要求。此外,由於60GHz 射頻應用的鎖相迴路之電壓控制振盪器是屬於窄頻,相對應的窄頻類比二倍頻器則可應用於此第一級的本地振盪,這樣可降低消耗功率、增加工作頻率空間並濾除高階諧波;再者,加入二倍頻於頻率合成輸出,可以減緩振盪器和除頻器等工作頻率的限制。對應到這些設計,仍存在著很多的架構和電路技術用來實現單晶片的解決之道,同時也具備著合理的晶片面積和消耗功率以符合我們的規格之需求。
其他識別: NSC99-2628-E005-008
Appears in Collections:電機工程學系所



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