功率谱密度约束下多频激励的非线性失真研究

多频激励信号通过放大器后产生的非线性失真对测量准确性具有较大影响。本文对功率谱密度约束下的多频激励信号产生的非线性失真进行了定量和定性的研究，给出了不同谱线间隔、非线性阶数、谐波相位和频率分布下的数值计算结果，并从三个方面进一步阐释了非线性失真的作用机制。首先，通过仿真发现，二阶非线性时，由具有 Schroeder 相位的多频激励信号产生的二类失真分量的相位为随机分布，而不是和一类失真分量反相。其次，通过计算一类失真分量、二类失真分量以及总失真的变化，解释了通过对多个具有随机相位的多频激励信号产生的非线性失真求平均来减小二类失真分量影响的测量方法。最后，发现了具有 Schroeder 相位的多频激励信号所产生非线性失真的特殊分布机制。本文的研究对准确评估和深入理解非线性失真具有重要意义。

Nonlinear distortion analysis for multisine excitation constrained by power spectral density

Nonlinear distortion introduced by an amplifier when subjected to a multisine excitation decreases the measurement accuracy in many metrological and measurement areas.In this paper,we performed qualitative and quantitative analyses of the nonlinear distortion with the multisine excitations constrained by a constant power spectral density.We present the numerical results with respect to different tone spacings,nonlinear orders,harmonic phases and tone distributions.Moreover,three as-pects of contributions are made to further reveal the distortion mechanism.First,we find that the typeⅡ components for Schr-oeder-phase multisines distribute uniformly but not all in anti-phase to the typeⅠcomponents for the second order nonlinearity. Second,we simulate the variance of the typeⅠand Ⅱ components and their summation to explain the principle of reducing the type Ⅱ distortion by averaging the results obtained using multiple realizations of random-phase multisines.Third,we observe a special distortion distribution mechanism for the Schroeder-phase multisine excitation.The results contribute to a better estima-tion and understanding of the nonlinear distortion.