本研究乃是使用台積電TSMC 0.25mm CMOS製程來實現一個具有四相位正交輸出應用於無線通信網路802.11a的壓控振盪器，該電路的四個輸出相位分別為90°、180°、270°、360°。本電路於模擬時其相位雜訊（phase noise）在1MHz處可達到 -122.74dBc/Hz，振盪頻率為4.441GHz ~ 5.323GHz，調頻範圍（tuning range）為0.882GHz約為18%，輸出功率為 -7.67dBm，消耗功率為15.8mw。

　　　　　In this paper, TSMC 0.25mm CMOS technology is used to implement a low-phase-noise quadrature VCO, which is suitable for an 802.11a wireless local area network (WLAN). The four phases of VCO outputs are 90°, 180°, 270° and 360°, respectively. As the simulation result shows, the tuning frequency is 4.441GHz~5.323GHz, the phase noise of the design is –122.741dBc/Hz offset 1 MHz, and the tuning range is 0.882GHz, which is about 18%. The output power is –7.67dBm, and the power consumption is 15.8mw.