| Summary: | 碩士 === 長庚大學 === 電子工程學系 === 101 === This thesis proposes a novel phase shifter and its application. With using this new type of phase shifter in the design of a low-power, high-performance voltage-controlled oscillator will be depicted in the VCO design, the novel phase shifter is played a role as the passive feedback circuit, that can avoid the losses generated from the conventional LC feedback network appropriate phase. and provide a turntable and stable oscillation signal.
The novel phase shift adopts a structure similar to the conventional reflection-type phase shifter, but the branch line coupler of the phase shifter is changed by using a new type trans-directional coupler. The trans-directional coupler is a 3-dB coupler and allow through and coupled ports located at the same transmission line and two outputs located at the other coupled transmission line. By connecting varactor at the through and coupled port, and applying reverse bias to the varactor , the phase shifter can be implemented without adding extra blocking capacitor.
To verify the performance of the proposed phase shifter, a 2.4GHz VCO is designed and fabricated. This oscillator is fabricated on PCB substrate . The measured oscillation frequency range is from 2.468 to 2.6GHz, which is corresponding to a fractional bandwidth 5.34%.The measured phase noise at 1MHz offset is -124.52dBc/Hz and output power of -3.14dBm.The power consumption is about 3.552mW. The figure-of-merit of this oscillator is about -186.86dBc/Hz.
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