1999 年美國聯邦通訊委員會制定了一個工作頻率的範圍在402~405MHz 並有十個頻道寬為300kHz 的無線頻帶稱作醫療植入式通訊服務。其應用的範圍適合具完全積體化的極低功耗並能在短距離下更快速的資料傳輸速度的人體植入式電子輔具。在設計講求小面積,低功率消耗的植入式視覺輔具的分數型頻率合成器的過程中,我們利用降低金屬繞線電感以增加品質因素以及降低壓控振盪器KVCO 的方式提升振盪器的相位誤差的效能。最後使用TMSC 0.18um 標準CMOS 製程使用1.5V 的系統電壓實現了一個核心面積為1.56mm2,功率消耗為2.93mW,佈局後模擬頻率鎖定時間小於100us 而量測之相位雜訊在160kHz 處為-100dBc/Hz 並符合MICS 系統的分數型頻率合成器。The 402-405MHz medical implant communication service (MICS) has been allocated by US Federal Communication Commission (FCC) in 1999 to provide 10 channels with 300 kHz bandwidth, of which application is suitable for full integration human implantable prosthetics with ultra-low power consumption and higher data rate in a short distance. In the thesis, a fractional frequency synthesizer is designed for implantable visual prosthetics which aims at small area and low power consumption, reduction of parasitic resistance of metal spiral inductor and low KVCO of voltage-controlled oscillator so as to realize an MICS-compatible fractional frequency synthesizer with core area of 1.56mm2, power consumption of 2.93mW, post-layout-simulation locking time of less than 100us, and measured phase noise of -100dBc/Hz at 160kHz offset for 1.5V supply voltage in TSMC 0.18 mm standard CMOS process.