针对PHS通信系统,综合采用了反型数控MOS变容管、数控MOS变容管单元矩阵、动态元素匹配、流水线MASH∑△调制器等多项旨在提高新型全数控LC振荡器(DCO)性能的电路技术,在SMIC0.18μmCMOS工艺下设计了一种低噪声低功耗的DCO.经测试得到,该DCO的中心振荡频率为3.1GHz,频率调节范围为120MHz,电源电压为1.8V,电流为2.8mA.当振荡在3.1GHz时,该DCO输出信号在100kHz与1.2MHz频偏处的相位噪声分别为-102.3和-122.6dBc/Hz.测试结果表明,该DCO与国际上DCO设计的最新水平相比,在相位噪声与功耗等方面具有较高的优势.
This paper presents a novel low noise,low power fully digitally controlled LC oscillator (DCO) for PHS transceiv- ers in an SMIC 0.18μm CMOS process. To improve the performance of the DCO,several circuit techniques,such as inversion- mode digitally controlled MOS varactors,a digitally controlled MOS varactor matrix,dynamic element matching,and a lined MASH ∑△ modulator, are used. The measured phase noise of this DCO at 100kHz offset frequency at 3.1GHz is below - 102.3 and down to - 122.6dBc/Hz at 1.2MHz while drawing 2.8mA of current from a 1.8V supply. Compared with state of the art DCOs,the measurement results demonstrate that our DCO features superior phase noise and power consumption.