The Design Of Frequency Synthesizer In Mems Digital Gyroscope

In recent years,the speed of the micro-electro mechanical systems(MEMS) technology updating and research are advancing by leaps and bounds.Today’s MEMS gyroscope has many advantages such as a high working accuracy and increasing integration and high speed and so on.Because MEMS gyroscope has so many advantages,such systems has caused social warm attention and many countries are all trying to develop the technology since MEMS gyroscope has been initially and successfully developed.In such a development boom and a high degree of concern,MEMS gyroscopes will increasingly well known and used in the coming time.With the rapid development of MEMS related technologies,the exploration and design work of Micro-electro mechanical system are gradually deepening.This makes the study of the interface circuit and the sensing circuit associated with MEMS digital gyroscope become particularly important.This design of the frequency synthesizer structure is mainly used in digital gyroscope and base on phase-locked structure.First, the system design starts from the traditional frequency synthesizer working principle of each parts of the structure and then proceed to the better performance of the structure and design of an in-depth study.Both analog and digital portions are contained in this system.In the circuit design parts of the gyroscope sensor, the analog circuit occupies an important position.MEMS gyroscope design generate a key role in inter face circuits design for frequency synthesizer.But now MEMS gyro performance requirements of a variety of system applications need are becoming more and more high.Analog circuits are difficult to meet the design requirement,because the circuit design are complex and difficult.The mix of digital and analog circuits not only contain the advantages of the two circuits also can better meet the design requirements of the system.This design concept will significantly improve system performance.Circuit design is mainly based on no dead zone effect of PFD, current steering charge pump, a second-order passive loop filter, five delaying parts voltage-controlled oscillator and multi-level and dual-mode structure of a programmable frequency divider.This system reduces the noise interference and other adverse factors circuits.Drawing the system layout after the parameter design and MOS tube level circuit design is completed.The circuit design platform is at Cadence Spectre and the layout using Cadence Virtuoso.System design is based on 0.5um CMOS N well process.The input signal frequency is from 4 KHz to 20 KHz square and output signal frequency up to 1MHz to 10 MHz when the system operates at a 5V supply voltage.The simulation phase noise is-145 d Bc / Hz at 10 KHz offset frequency.After simulation, frequency synthesizer in digital MEMS gyroscope design meet the requirements.