The Design And Implmentation Of Low Phase Noise LC Oscillators

In many military and civilian areas frequency signal sources has been used, and its use is becoming more and more widely. As well as in the navigation and radar, satellite tracking, space communication and frequency metrology, and other fields has been widely used. With the gradual development of modern technology, the demand began to source more stringent accuracy requirements. Therefore, the oscillator frequency source which is an essential part of an electronic system,people demand their precision more and more strict. But the phase noise of the oscillator has become a crucial factor limiting the performance of electronic system performance.People have to find ways to improve the phase noise of the oscillator to improve frequency signal source to meet achieve better demand indicators. Because of LC oscillator‘s low cost and wide adjustable range, There are also some market applications. Thus, in the design and implementation of real LC oscillators deeply studying of the phase noise of theory to provide an efficient approach to improving the phase noise is very important.Firstly, this paper defines the phase noise on the perspective of time domain and frequency domain, then achieve the conversion between them. Secondly, this paper analysis several international general models of phase noise and comparing them.So as to select the simplest and most intuitive phase noise model- Leeson model as a model which is be used in this researching. However, the classic Leeson model does not research in-depth on the phase noise of a specific relationship quality factor and oscillation circuit parameters. Therefore, on the basis of Leeson model, The single terminal network of Razavi’s definition of loaded quality factor is extended to two port network, then we can cat practical expressions of loaded quality factor and the circuit parameters on the basis of Leeson model, we use the dual-port network theory to derive explicit expressions Pierce LC oscillator circuit parameters and load quality factor to obtain the theoretical QL varies circuit parameters. Then people can use this theory to optimize QL by controlling circuit parameters, and use ADS simulation software and MALTLAB to test and verity the theory, on the basis of the design of low-noise transistor capacitance LC oscillator. Then this paper introduces several common phase noise measurement techniques and analysis their different occasions using measurement techniques and their principles and characteristics. Lastly, we use the RS signal source to measure the phase noise of LC oscillator phase we have made. Experiments proved to improve the on-load quality factor from the viewpoint of reducing the phase noise of the proposed method is feasible, and also verify the resonant circuit LC oscillator parameters in a certain range can effectively improve the LC oscillator phase noise performance.