| Summary: | 博士 === 國立臺灣大學 === 電信工程學研究所 === 95 === Research on the development of Si-based low phase-noise oscillator and the low-power oscillator mixer is presented in this dissertation.
In this dissertation, the measured micromachined inductors and the equivalent circuit models above X-band on low resistivity silicon substrate (33 Ω-cm) with improved quality factors are investigated. The experimental results obtained for different-turns inductors show that the inductors quality factor can be improved after shunting metal from metal1 to metal4 and reducing the parasitic capacitance between the inductors and the lossy Si-substrate. In this work, it is observed the quality factor can be improved up to 107%. The measured self-resonance frequencies of the micromachined inductors are above 30 GHz.
A 22-GHz push-push oscillator using micromachined inductors is implemented in TSMC 0.35-μm CMOS technology. Compared with the recently reported performance of Si-based VCOs around 20 GHz, the low phase-noise 22-GHz oscillator with better Figure-of-Merit (FOM) is obtained by using the micromachined inductors. This phase noise is about 6-dB phase noise improvement from the free-running oscillator with regulator inductors. The fundamental rejection is 18 dB. This chip was fabricated in a low-cost process while demonstrating the low phase noise. This chip is also the first 0.35-μm CMOS oscillator with oscillating frequency over 20 GHz.
In order to improvement the fundamental rejection of the 22-GHz push-push oscillator. Another 30-GHz low-phase-noise 0.35-μm push-push oscillator using micromachined inductors is also developed and implemented in 0.35-μm CMOS technology. The parasitic capacitor of the nMOS devices service as the capacitor in the LC tank. Compared with the recently reported performance of Si-based VCOs around 30 GHz, a low phase-noise 30-GHz VCO with better FoM and higher output power is obtained by using the micromachined inductors. The measured result demonstrates about 5.1-dB phase noise improvement is achieved compared with the free-running VCO with regular inductors. The fundamental rejection is improved 12 dB from the 22-GHz push-push oscillator.
Regarding the phase noise reduction, a low phase-noise X-band push-push oscillator using proposed feedback topology is presented. By using the proper phase delay in the feedback loop and high transconductance of the current source, a low phase-noise oscillator is achieved. The amplitude stability and phase stability are analyzed, the phenomena of the phase noise reductions are derived, and the
device-size selections of the oscillator are investigated. The time-variant function, impulse sensitivity function, is also adopted to analyze the phase noise reductions. This self-injected push-push oscillator achieves low phase noise of -120.1 dBc/Hz at 1-MHz offset from the 9.6-GHz carrier. It is also the first attempt to analyze the second-harmonic self-injected push-push oscillator. 1-MHz offset from the 9.6-GHz carrier. It is also the first attempt to analyze the
second-harmonic self-injected push-push oscillator.
Finally, a downconversion double-balanced oscillator mixer using 0.18-μm CMOS technology is proposed. This oscillator mixer consists of an individual mixer stacked on a voltage-controlled oscillator (VCO). The stacked structure allows entire mixer current to be reused by the VCO cross-coupled pair to reduce the total current consumption of the individual VCO and mixer. This oscillator mixer requires a
lower supply voltage and achieves a higher operating frequency among recently reported Si-based self-oscillating mixers. The mixer in this oscillator mixer also achieves a low power consumption compared with recently reported low-power mixer.
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