Chapter 8 Electrical Noise: An Overview

对于一个Vp*sin(2pi t/T)的电压

V(t)=V^2_Psin(2\pi f\cdot t)

Average Power Dissipated:

{\frac{1}{T}\int_{0}^{T}V(t)^2dt}=\frac{V^2_P}{2}

Mean-Square Voltage:

{\frac{1}{T}\int_{0}^{T}V(t)^2dt}=\frac{V^2_P}{\sqrt{2}}

Root-Mean-Square Voltage

V_{RMS}=\sqrt{\frac{1}{T}\int_{0}^{T}V(t)^2dt}=\frac{V_P}{\sqrt{2}}

在频率domain 分析:

Power Spectral Density (PSD) = Vrms^2/fres = V^2/Hz

V_{in,noise,rms}=\frac{V_{out,noise,rms}}{A}

对于多级系统, 第一级噪声影响最大! 需要减少第一级噪声, 后级会被增益抑制

Thermal Noise 热噪声

对于电阻, 其热噪声模型

对于一个RC filter, 其输出或者输入噪声 output RMS noise voltage is

V_{in,noise}=V_{out,noise}=\sqrt{\frac{kT}{C}}

noise 由电容决定, 而不是由电阻决定, 这一点特别重要!!!

SNR: Signal-to-Noise Ratio

SNR=20log\frac{V_{signal,rms}}{V_{noise,rms}}

Shot Noise

电流流过PN节产生的噪声, 正比于电流

I_{short}^2(f)=2qI_{DS} \text{ with units of }A^2/Hz

Flicker Noise 闪烁噪声

Also known as pink noise., 与频率成反比