The Development Of A Low Phase Noise Oscillator

With the development of modern communication and radar technology, quality of high stability frequency sinal source becomes one of key parts which affect system performance good or bad, conseqently, fabricating high stability crystal oscillator and improving phase noise index is an urgent assignment.In addition, as frequency synthesis technic has been strict to single crystal oscillator reference source,making low phase noise crytal oscillator has wide prospect. This paper describes phsics property and electrcial parameter nature of crystal resonar, its advantage crystal owes in being frequency control component and basic work principle of feedback crystal oscillator.The basic concept of frequency stability degree followed phase noise also be delt with, meanwhile, writer gives usual expression way of phase noise, reason of forming phase noise and a variety of contributors to influence on it. Phase noise time-domain and frequency-domain presentation ways also are given.Base on transistor amplifier noise model analyse,component parameter value of smaller noise coefficient rationally be chosen.According to Leeson Model which has proposed the relationship between output signal source noise and input port noise in feed-back oscillator,an experimental high stability low phase noise oscillator circuit be designed by writer. Writer has analyzed master oscillator circuit's every component value of effect on crystal Q-loaded, proposing method of decreasing crystal Q-loaded loss. An Effective way of lowering phase noise is discussed.In the design process, high frequency simulation tool soft serenade v8.7 of American Ansoft corportionan plays a important pole in oscillator circuit simulation and debugging.Through soft optimization, writer has get a group of fitting parameter and assembled them in the factual circuit board, debugging it.Finally, PN9000 phase noise test system is used to measure sample index.According experiment results are...