Study And Application Of High Performance Microwave And Millimeter-wave Oscillators

Oscillator is one of key components of radar and communication systems. As the technology of wireless communication and millimeter-wave radar applications develop rapidly, they exert more stringent requirement on the performance of oscillator such as lower phase noise, higher output frequency and greater output power. Therefore, it is necessary and important to study high-performance oscillator. This dissertation mainly focuses on the design and application of some high-performance oscillators, including push-push dielectric resonator oscillator, substrate integrated waveguide (SIW) voltage-controlled oscillator (VCO), W-band continuous-wave oscillator, and W-band pulsed oscillator. The main work of the dissertation is summarized as follows.(1) A new phase-locked push-push dielectric resonator oscillator (DRO) circuit is proposed. In this circuit, the phase-locking is implemented at the fundamental frequency of the push-push DRO, and the fundamental waves of the sub-oscillators are combined by an out-of-phase Wilkinson power divider. Hence, dual-band high-stability output can be realized. As a proof of concept, a Ku-band prototype circuit has been designed and fabricated. The measurement results verify its good performance of phase noise and spur. In addition to fundamental wave phase-locking, fundamental wave injection locking is also applied to push-push DRO. Two injection locking modes are introduced, i.e. the in-phase injection locking and the out-of-phase injection locking, and their influence on locking bandwidth and fundamental wave rejection are analyzed. The analysis shows that the out-of-phase injection locking is superior in terms of locking bandwidth and fundamental wave rejection.(2) Based on electromagnetic simulation tools and the negative resistance oscillator theory, the design of the Ka-band SIW VCO is discussed in detail. A Ka-band SIW VCO is demonstrated using low cost substrate. The experimental results show that the tuning bandwidth, the output power and the phase noise performance of the VCO can meet the demands of practical engineering. To our knowledge, the oscillator is the first Ka-band SIW Gunn VCO.(3) Low-noise, high-stability local oscillator (LO) array is highly demanded in W-band imaging systems. In this context, a W-band four-way LO source is implemented using injection-locked Gunn oscillators. Compared with these conventional designs using the IMPATT amplifiers, this design features low amplitude noise. However, W-band injection-locked Gunn oscillators always have the disadvantage of narrow locking bandwidth. To increase it, a W-band second subharmonic injection-locked phase-locked loop (2nd S-ILPLL) circuit is proposed. With a 0.1 mW U-band injection power, it is found that the W-band locking bandwidth of less than 20 MHz is increased to more than 1 GHz using the 2nd S-ILPLL circuit.(4) Firstly, based on the coherence analysis of the output pulse of the single stage injection-locked pulsed amplifier chain, a timing scheme necessary for multi-stage injection-locked coherent pulsed amplifier chain is given. Secondly, the power combing effect of the injection-locked amplifier chain is analyzed. Thirdly, a W-band high power coherent pulsed transmitter has been developed based on the above analyses. The transmitter uses high power pulsed IMPATT oscillators as the power output stages, and its output power is more than 20 W across 94.2±0.16 GHz. The peak output power of 22 W is achieved at 94.2 GHz. The locking bandwidth is about 600 MHz. Meanwhile, due to injection locking and bias pulse compensation, the intra-pulse chirping noise is greatly suppressed, resulting in further improving the coherence of the output pulse.(5) To achieve even higher output power, a novel W-band pulsed power combiner is presented. Injection-locked coherent pulsed amplifier chain is used as the basic power unit of the combiner. H-plane waveguide T-junctions are used as the 3 dB power dividing/combing networks. The coherent peak output power of 28.4 W is achieved at 94 GHz with 91 percent power combing efficiency. To the best of our knowledge, the power combing efficiency is superior to that of any W-band nonresonant combiner in the literature we know.