在無線通訊系統中，頻率合成器是用來做訊號頻率的升降之用。其中，壓控振盪器與除頻器更是頻率合成器電路裡的核心電路之ㄧ。對壓控振盪器而言，必須提供低相位雜訊的輸出，以避免相鄰雜訊訊號經由混波轉換產生干擾。而壓控振盪器的輸出會經由除頻器降頻至與參考訊號相同的等級，與相位頻率偵測器做比較以校正壓控振盪器的輸出，故除頻器需要有高頻操作的能力。由於應用於無線通訊系統中，壓控振盪器與除頻器都必須要有低功耗的特性。

本論文提出了共一個壓控振盪器與兩個除頻器電路。其中壓控振盪器是使用二極體耦合的四相位輸出振盪器。一個使用主動電感的注入鎖定除頻器。以上電路使用台積電0.18微米CMOS製程來完成。另一個則是一個使用三維電感的雙頻帶注入鎖定除頻器，使用聯電90奈米製程去實現。

首先，我們提出一個將兩組以n型電晶體為核心、透過二極體耦合形成四相位輸出壓控振盪器的技術。當控制電壓由0到1.2 V變化時，四相位壓控振盪器的低頻帶可由4.50 GHz調到4.72 GHz，而高頻帶則由11.61 GHz到11.84 GHz。而在低頻帶輸出頻率4.5 GHz，所量測到的相位雜訊在1 MHz位移時為-115.54 dBc/Hz。

其次，我們呈現一個使用可調主動電感的低功耗寬鎖定範圍注入鎖定除頻器，其可調主動電感是以兩組交錯耦合電晶體串聯堆疊而成。藉由直接在橫跨於主動LC共振腔的金氧半場效電晶體的閘極端注入訊號，我們可以得到除二的功能。當供給電壓為1.6 V時，振盪頻率為1.3至0.8 GHz。在注入強度為-3dBm時，其除二模數的操作頻率為1.5至3.8GHz。

最後，我們討論一個雙頻帶的互補式金氧半LC共振腔注入鎖定除頻器，以一個交錯耦合的n型金氧半振盪器與雙頻帶LC共振腔來完成。在這個電路中我們會使用一個三維的變壓器。當直流的閘-源極電壓為0.7 V時，不需透過調整電壓，振盪頻率可以有兩個頻帶，高頻帶約24.4 GHz。低頻帶約5.5 GHz，事實上它是一個激發出來的頻帶。我們量測到的高 (低) 頻帶鎖定範圍為46.5 (10.4) 至51.4 (11.9) GHz。

In wireless communication system, frequency synthesizers are used to implement the frequency up/down converting of signal. In a frequency synthesizer, voltage-controlled oscillator (VCO) and divider are the key blocks. For VCOs, low phase-noise output is required to avoid corrupting the mixer-converted signal by close interfering tones. The frequency of output signal of VCO is divided down to the level of reference signal, and is compared with reference signal by a phase frequency detector (PFD) to adjust the output of VCO. Therefore the dividers must have the ability of high frequency operation. Because of wireless application, both of them should operate at low power consumption.

This thesis proposes one VCO and two frequency dividers. The VCO provides quadrature outputs by diode-coupling technique. One divider is an injection locked frequency divider (ILFD) using active-inductor. The above circuits are fabricated in the TSMC 0.18 μm CMOS process. Another one is a dual-resonance ILFD using 3-dimensinal (3-D) transformer implemented in the UMC 90 nm process.

Firstly, a diode-ring coupling technique has been used to design a quadrature voltage-controlled oscillator (QVCO), which consists of two n-core VCOs. The oscillating low-band frequency of the QVCO can be tuned from 4.50 GHz to 4.72 GHz, and the oscillating high-band frequency of the QVCO can be tuned from 11.61 GHz to 11.84 GHz while the tuning voltage varies from 0 V to 1.2 V. The phase noise of the high band oscillation frequency 4.5 GHz is -115.54 dBc/Hz at 1 MHz frequency offset.

Secondly, we present a low power wide-locking range ILFD with tunable active inductor (TAI) which is based on two pairs of cross-coupled transistors stacked in series. The divide-by-2 function is performed by injecting a signal to the gate of direct injection MOSFETs across the active LC resonator. At the supply voltage of 1.6 V, the free-running divider is tunable from 1.3 to 0.8 GHz. At the incident power of -3 dBm the operation range in the divide-by-2 mode is from the incident frequency 1.5 to 3.8 GHz.

Finally, a dual-band CMOS LC-tank ILFD is proposed. It is realized with a cross-coupled nMOS oscillator with a dual-resonance LC-tank. A 3-D transformer is used in the implemented ILFD. At the dc drain-source voltage of 0.7 V, the free-running ILFD can have two frequency bands without tuning, and the high-band oscillation frequency is 24.4 GHz. The low-band oscillation frequency is 5.5 GHz. The low-frequency band is an excited band. The measured locking range is from 46.5 (10.4) GHz to 51.4 (11.9) GHz for the high- (low-) frequency band.

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