在無線通訊系統中，頻率合成器為提供一穩定信號供混頻器混頻使用。而在頻率合成器迴路之中，壓控振盪器為其主要核心電路。為了避免相鄰雜訊訊號對混頻造成干擾，故要求壓控振盪器須要是低相位雜訊。且在無線收發器中，常有鏡像雜訊存在而影響系統的性能，必須利用正交架構來消除鏡像雜訊，因此對於產生正交相位的振盪源也必須是低相位雜訊。但由於在設計振盪器時考慮的參數是多方面的，故定義一優質指數來評斷振盪器的優劣。
首先，本論文提出了一改善相位雜訊的四相位壓控振盪器以及兩種新型雙頻帶之壓控振盪器。在第一個電路中，改良型的四相位壓控振盪器利用共閘極耦合代替傳統式共源極耦合。此電路在電壓0.8V時操作頻率為9.8GHz，其功率消耗為9.76mW，有較寬的調變範圍從8.52GHz到10.56GHz，以及輸出之相位雜訊在距離載波頻率1MHz 處所量測之結果可達-118.88dBc/Hz，其優質指數FOM為-188.86 dBc/Hz。
其次，第二個電路呈現以分散式左手LC網路結構的一個雙頻帶環繞式駐波振盪器，其共振腔主要是由四個單位元件以串聯疊接方式組成，並以兩對交叉耦合器來補償左手共振腔的阻抗；至於雙頻帶的產生是以電壓控制變容器來完成。此電路使用台積電矽鍺0.18微米製程實現。量測數據結果輸出高頻的部份是6.73GHz至8.6GHz，而低頻部份從3.68GHz至3.73GHz。
最後，第三個電路類似於第二個電路也以左手共振腔架構的雙頻帶模式之駐波壓控振盪器，不同於第二個電路的部份是雙頻帶的產生是以電晶體切換方式來執行。此電路是在台積電0.18微米製程下完成製作。量測數據結果，輸出訊號高頻的部份從7.18GHz至7.55GHz，而低頻部份從4.5GHz至4.64GHz。

In wireless communication system, frequency synthesizer offers a stable signal for mixers. And in the synthesizer network, voltage-controlled oscillator (VCO) is the core block in this network. In order to avoid the adjacent noise to interfere mixing, we ask the voltage-controlled oscillator requires to have low phase noise. In RF transceiver system, there exists image noise and it leads to affect the system quality. We used the quadrature architecture to eliminate the image noise, for the reason that produces quadrature phases by quadrature voltage-controlled oscillator (QVCO) to lead to low phase noise. Since the the parameters should be traded off when we design VCO, we define a figure of merit (FOM) to characterize this VCO’s performance.
Firstly, this report presents the quadrature VCO with improvement of phase noise for two novel dual-band VCOs having left-handed resonance. In the first chip, the proposed quadrature VCO uses common-gate coupled transistor instead of conventional common-source coupled transistor. The oscillation frequency QVCO range from 8.52 to 10.56 GHz and the power consumption is 9.76 mW at 0.8 V supply voltage. The measured phase noise is -118.88 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 9.86 GHz, and the FOM is -188.86 dBc/Hz.
Secondly, the second chip propose a dual-band rotary standing-wave oscillator (RSWO) implemented with a distributed left-handed (LH) LC network. The network consists of four unit cells of left-handed LC resonator stacked in series. In addition, two pairs of cross-coupled transistors are used to compensate the loss of resonator. Varactors are used as the control to switch on/off the high or low-frequency bands. The proposed RSWO has been implemented with the TSMC 0.18 m SiGe BiCMOS technology. For measuring results, the output signals in the high-band frequencies are in the range of 6.73-8.60 GHz and the low-band frequencies of the output signals are in the range of 3.68-3.73 GHz.
And finally, the third circuit design is similar to the second circuit. It use the structure of left-handed (LH) LC network, but the LC resonator is in shunt with a pair of cross-coupled transistors. With obviously different parts, the third circuit uses a pair of MOSFET mode-switches to switch on/off the frequency bands. In the fundamental mode, the SWO operates at higher frequency band. In the harmonic mode, the oscillator provides lower frequency band output. The proposed SWO has been implemented with the TSMC 0.18 m 1P6M CMOS technology. It can generate differential signals in the higher band frequency band which has the frequency range of 7.18-7.55 GHz and it produces the artificial signals in the lower frequency band which has the frequency range of 4.5-4.64 GHz.

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