Study On Low Phase Noise Microwave And Millimeter-Wave Oscillators

As one of the core components of the radar and wireless communication system,Oscillator provides a stable signal.In the several items of the oscillator such as frequency,output power,harmonic suppression and phase noise,the phase noise performance is one of the most important parameters.This dissertation aims to obtain low phase noise performance among different oscillators.At the beginning of the dissertation,the different phase noise models are studied and used to get some methods of improving the phase noise performance.Some technologies are researched and used to design low phase noise oscillators.The content is included as following:?1?The dissertation reviews the different topologies of low phase noise oscillators from the 21^st century and gives some classically designed methods of low phase noise oscillators.?2?The dissertation systematically introduces the basic theory and analytical method of the oscillator firstly,then gives three types of phase noise model of the oscillator and summarizes several methods to improve the phase noise performance.Besides,the accurate measurement of phase noise is also important,so three different measuring methods of phase noise performance are discussed.?3?For the parallel feedback-configuration oscillator,the method is proposed to design a low-phase noise oscillator by increasing the feedback loop group delay and optimizing the insertion loss of a high-Q resonator based on the linear time-invariant phase noise model of Lesson.By taking advantages of mixed electronic and magnetic coupling,a transmission zero close to passband is introduced in the feedback loop filter.The high frequency-selective filters are used to design low phase noise oscillators or voltage control oscillator?VCO?.The measured results show that the low phase noise oscillator based on the stubs-loaded nested split-ring resonator?SLNSRR?oscillates at1.98GHz,and the phase noise performance reaches to-127.22dBc/Hz and-145.43dBc/Hz at 100kHz and 1MHz offset frequency,respectively.Besides,by considering group delay and loop insertion loss at the same time,the phase noise figure-of-merit?PNFOM?is adopted as the designed index of the low-phase noise oscillator.The designed oscillator oscillates at 2.037GHz and the phase noise performance at 100kHz and 1MHz offset frequency are-127.95dBc/Hz and-146.47dBc/Hz,respectively.?4?After completing the single-ended feedback-configuration low phase noise oscillator based on the designed SLNSRR,the low phase noise differential oscillator is further designed by using the differential circuit to suppress the environmental noise,substrate noise and power supply noise.The phase noise optimization of the differential oscillator when compares to the single-ended oscillator is analyzed theoretically.The tested results show that the phase noise of the differential oscillator based on the quarter-wavelength stepped-impedance resonator?QSIR?has an excellent performance of-130.19dBc/Hz at 100kHz offset frequency when the oscillated frequency is 1.952 GHz.The experimental results show 2.8dB phase noise improvement of the differential oscillator when compares to the single-ended oscillator.?5?A negative resistance-configuration low phase noise oscillator and a feedback-configuration low phase noise oscillators are designed when we both consider the phase noise model of Lesson and Hajimiri.Based on the basic principle of substrate integrated waveguide?SIW?,a combline resonator with high-Q is proposed,and a low phase noise oscillator with the negative resistance configuration in X-band is designed.The test results show that the phase noise of the oscillator oscillates at 10.07GHz with the phase noise performance of-127.25dBc/Hz at 1MHz offset frequency.Besides,by using the high harmonic suppression filter to improve the phase noise of the oscillator,a high harmonic suppression filter based on SIW quarter-wavelength resonator?QWR?is proposed,and a feedback configuration oscillator is designed based on the filter.The tested results show that the oscillation frequency of the oscillator is 8.08 GHz,the second and third harmonic suppression are 39.23dB and 67.64dB,respectively,and the phase noise at 1MHz frequency is up to-130.36dB/Hz.?6?As an application example in a simple detection radar,the low cost and low power consumption Doppler radar with the miniaturized size is designed based on Ka-band negative resistance-configuration low phase noise oscillator in this dissertation.The Doppler radar is realized by the main circuit and the antenna array on different substrates respectively and is designed in a cylindrical cavity with a diameter of 20mm and a height of 6mm.The Doppler radar can detect the moving velocity of objects in a certain distance and has a certain sensitivity.With small size and low power consumption,the Doppler radar has a good prospect in the engineering application.