Modeling And Design Of Rotary Travelling-wave Oscillator

As one of the pivotal component of the microprocessor, the clocking system has been anextremely important role for signal synchronization. With the rising of the operation frequencyand the lowering the process node, the traditional clocking systems are hard to satisfy theperformance need of the next generation microprocessor. For the reason of the high frequencyand low jitter clock signal generation and low power clock network, the rotary clockingtechnique has been seen as the one of the research direction of the next generation clockingsystem. Rotary travelling-wave oscillator is the core of the rotary clocking technique, comprisedby a close-looped transmission line and several negative impendence compensation cells,generating square-wave signal for the clocking distributed network.The main goal of this thesis is modeling and design rotary travelling-wave oscillator, and thecontent is as follow:Firstly, the traditional rotary travelling-wave oscillator circuit is discussed and analyzed,and divided into two parts, oscillation part and compensation part. Then, the voltage-controlledrotary travelling-wave oscillator using frequency-adjusted mechanism is presented. As a result,these three parts of the voltage-controlled rotary travelling-wave oscillator circuit are modeling,respectively. The circuit model of the oscillation part comes from the resonant and transmissionline theory; for the compensation part, the MOS voltage-current feature is discussed, analyzingthe negative resistant feature and modeling; for the frequency-adjusted mechanism, three MOSvaractors are shown. Accordingly, the accumulation-MOS varactor is chosen for the thevoltage-controlled rotary travelling-wave oscillator.Secondly, for the swift and accurary simulation and large-scale-multi-varation experiments,an automatic design tool for voltage-controlled rotary travelling-wave oscillator, RotarySim, ispresented. This tool is based on the3-D electromagnetism-field computer FastHenry and thesimulation tool Hspice. FastHenry can compute the impedance matrix of the on-chiptransmission line, and translate into SPICE netlist. Through the varation of the multi-parameterof the voltage-controlled rotary travelling-wave oscillator, RotarySim can output a quantitivenetlists, which are directly used in Hspice. Based on the RotarySim, a process-sensitivityexperiment is presented, proving that on-chip varaction can not be ignored.Thirdly, using the RotarySim, a design flow of the voltage-controlled rotary travelling-waveoscillator is presented, which is from loop shape to size design and parameter adjustment, toperformance verification. Based on the design flow, a voltage-controlled rotary travelling-waveoscillator is design, the center frequency is about5.8GHz, and the frequency range is about3GHz.Finally, the conclution and the acknowledgement are presented for the future.