【摘要】 ∑Δ调制器输出码流的频谱中含有大量高频噪声,在对其进行FFT谱分析时,需要加窗函数抑制这些高频噪声对基带噪底的泄漏。由于∑Δ调制器输出码流的噪声主要是高频噪声,因此需要滚降衰减较大的窗函数,窗函数选择不当会使其有效位数有2～6位的下降。实例表明,对于超过20bit精度的∑Δ调制器,选用Balckmanharris窗比Hanning窗更合适。更多还原

【Abstract】 The output spectrum of Sigma-Delta Modulator contains lots of high frequency noise, which will leak into the base band. This paper put forward that only the fast-roll-down attenuating windows are suitable for Sigma-Delta Modulator FFT analysis, and the unsuitable windows will lead to 2～6 bits ENOB drops. Experiment shows that Balckmanharris window is more suitable for 20-bit Sigma-Delta Modulator than Hanning window.更多还原