Design Of A Digitally Controlled Oscillator In Millimeter-wave Band Based On CMOS Process

With the rapid development of mobile communication technology in recent years,the world has gradually entered the era of 5G and the Internet of Things,which also puts forward higher requirements for the performance of wireless communication system.As the heart of wireless transceiver,phase-locked loop frequency synthesizer provides stable local oscillator and clock signal for the whole wireless communication system,which has an important influence on the comprehensive performance of wireless communication system.At the same time,with the progress of semiconductor manufacturing process,the IC area and supply voltage margin are decreasing,which makes the digital circuit technology have a broader application prospect in the future.Therefore,the research of high performance digitally control oscillator conforms to the development trend of future communication technology and has very important research significance.In this dissertation,the analysis of the oscillator related knowledge and circuit structure is focused on,and the experience of relevant research at home and abroad is fully summarized.Based on the 40 nm CMOS process,a digitally control oscillator with wide tuning range and high tuning accuracy is designed,which works in the millimeter wave E band.The main work can be summarized as following:Based on the theory of electromagnetic field,the 3D physical modeling and simulation optimization of passive devices such as inductors and transformers are carried out with the help of electromagnetic simulation software,so that they can have accurate performance parameters in millimeter wave band.Three level capacitor tuning circuits are designed for coarse tuning,medium tuning and fine tuning,using and improving the Di CAD differential transmission line technology to build the coarse and medium frequency tuning circuits.Using on-chip transformer coupled multistage C-2C capacitor array as fine frequency tuning circuit.The source and analysis model of the oscillator phase noise are studied in depth,and a variety of phase noise optimization methods are used to improve the noise performance.This design has finally completed the design of the schematic diagram and layout of the digitally control oscillator,the circuit simulation based on layout is carried out,and the simulation results are analyzed and compared.The back-end simulation results show that: the frequency turning range of the designed digitally control oscillator is 80.45GHz?88.27 GHz,and the relative bandwidth is 9.27%.The highest tuning accuracy of the digitally control oscillator is 220 k Hz.At the lowest operating frequency 80.45 GHz,the phase noise is-91.68 d Bc/Hz at the 1MHz frequency offset.The layout area of the core circuit of the digitally control oscillator is 0.262mm×0.066 mm,and the total area of the layout including the pads is 0.536mm×0.462 mm.