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提出了一种数控最小变电容结构,采用互补型变容管两端跨接固定电容结构,可以使用较大尺寸变容管实现较小的最小变容值,从而减小了工艺误差对设计结果的影响,同时解决了大摆幅振荡信号下的非线性问题,缓解失配电容对失配率一致性对最小变容值的影响.在相同工艺下,最小变电容值减小接近50%.采用180nm CMOS工艺,基于最小变电容结构设计了全数控LC振荡器,通过改变各级数控变电容阵列的结构,提高全数控LC振荡器的频率分辨率.仿真结果表明:提出的最小变电容结构可实现7.42aF的最小变电容值;全数控LC振荡器的振荡频率范围为3.2~3.8GHz,输出电压摆幅为1.75V,中心谐振频率3.5GHz的相位噪声为-1.2×10-4 dBc/Hz,归一化价值因子FOM为211;在相位噪声、功耗、FOM等性能指标维持在同等水平的前提下,调频精度显著提高.
Proposed a minimum NC variable capacitance structure, using complementary varactors at both ends of the fixed capacitor structure, you can use a larger size varactor to achieve smaller minimum varactor value, thereby reducing the process error on the design results While solving the nonlinear problem under the large swing oscillation signal and alleviating the effect of the mismatch capacitance on the minimum capacitance caused by mismatch mismatch.With the same process, the minimum capacitance decreases by nearly 50%. A full-control LC oscillator is designed based on the minimum variable capacitance structure by using 180nm CMOS technology. The structure of the NC variable capacitance array at all levels is changed to improve the frequency resolution of the fully-controlled LC oscillator. The simulation results show that the proposed minimum variable capacitance structure The minimum capacitance of 7.42aF can be achieved. The full-scale LC oscillator oscillates at 3.2 ~ 3.8GHz with an output voltage swing of 1.75V and the phase noise of 3.5GHz at the center resonant frequency is -1.2 × 10-4 dBc / Hz, the normalized value factor FOM is 211; FM accuracy is significantly improved under the premise of the same performance indicators of phase noise, power consumption, FOM and other performance indicators.