5 Ghz - 10 Ghz Phase-locked Frequency Source

Frequency synthesizers play a important role in the electronic circuit，They haveevolved over the time.Their quality will impact on the electronic equipment. Frequencysynthesis technigue has a rapid development in the modern communication and radarsystem. And their excellent tagets which include low phase noise，low spurs，fastfrequency swithing have become a main orientation for the engineers.Frequencysynthesizer has three modes:DS,DDS,PLL,mixed-frequency synthesis.As the development of the civil frequency synthesizer，the technology and productquality become better. At the year of2008，the student Meng Hu desiged frequencysynthesizer with low spurs from2060MHz to2160MHz at the step of10kHz inUESTC.Its spurs lower than-65dBc and the phase noise lower than-90dBc@1kHz.Inthe2011，Nanjing Electronic Devices Institute desiged a frequency synthesizer with thestep of10MHz from7GHz to20GHz.And its phase noise lower than-72dBc/Hz@1kHz.The frequency synthesizer in foreign developed quickly. a variety offrequency synthesizer had face the world with low spurs、low phase noise、finefrequency step. A frequency synthesizer in the Phase matrix.INC had the index asfollows，its frequency step was0.001Hz. The swithing time lower than1ms and thephase noise lower than-110dBc/Hz@10kHz at20GHz. This article desiged a pll withthe lenth of10.5cm and the width of5cm.Its phase noise lower than-85dBc/Hz@10kHz from5GHz to10GHz.This article analyze three kinds of frequency synthesizer’s advantages anddisadvantages， then focus on the phase-locked frequency synthesis technigue,introduceit’s basic principles and development process，discuss the influence of devices on thewhole phase-locked loop，explain why phase-locked loop will generate the phasenoise and spurs and offer a solution to estimate them.This article designed a broadband frequency synthesizer with the length of10.5cmand the width of5cm，its phase noise lower than-85dBc/Hz@1kHz.It especiallyintroduce the design of the active filter which was convenient to debug andmanufacture. Finally,I point out the key element in the design of the circuit from the point of view in EMC and the details of the PCB.It could be able for the up-conversion system and down-conversion system,or bemixed with the other PLLs.