Design Of Clock Generation Circuit In MCU

IC clock is generated by the clock circuit,the ring oscillator is an important partof the clock circuit.As a simple circuit,due to ease of integration,has been widely usedin the field of electronic industry,medical,scientific research,petrochemical,health andepidemic prevention,environmental monitoring,etc.In the communication system,thering oscillator circuit generates a clock signal for data processing equipment and areference signal for a particular system.In general,the ring oscillator frequencyaffected by fluctuations in power supply voltage,which will directly affect thestability of the clock signal and reference signal it generates.To improve the ringoscillator in the paper,and to increase the calibration function,the crystal oscillatorand this circuit to use to select.This topic closely around the clock generation circuit of MCU circuit for anin-depth and systematic research.The clock generation circuit uses a ring oscillatorand an external crystal oscillator.The circuit has carried out the automation choice onthese two oscillators.The ring oscillator has been improved,by not only reducedthe oscillator frequency,but also reduced power consumption.Clock generation circuitof MCU in the papers is divided into four modules:improved ring oscillatormodule;external crystal oscillator circuit module;automatic selection of the oscillationmode module;the voltage source module.in this issue in-depth study and analysis ofthe four modules,and to use Cadence’s Hspice simulation tools for the simulation.Themain body of this design is the four modules.There are three main innovation for this topic:first, joined frequency calibrationmodule in the ring oscillator;second, provided three modes of oscillation for theautomatic selection;third,by providing a small voltage sources to reduce oscillatorpower.This topic uses the CSMC’s0.35um technology to achieve layoutdesign.According to the simulation data of circuit,to get the proper device andsize,and to design the proper layout.According to the layout of parasitic parameter extraction,by means of circuit simulation,to ensure excellent performance of thecircuit,and to ensure the accuracy of the layout.This MCU’s chip has successfullytaped out.Finally,the performance of the chip and the direction of the work are brieflydiscussed.