【正文】
Noise amp。 Distortion in Microwave Systems ?Thermal(熱) Noise by Components amp。 Devices ?Atmosphere and Interstellar(星際的) Radiation ?Manmade Interference ?Distortion: Large Signal ?(Nonlinear Systems) ?Mixer amp。 Amplifier ?External Environment ?Internal Circuit Noise : Random Process! ?Noise: Small Signal ?SignaltoNoise (S/N) ?Bit Error Rates (BER) ?Dynamic Range ?Minimum Detectable Signal Level 實(shí)際放大器的動(dòng)態(tài)范圍 1 Thermal Noise ?Thermal Noise Random motion of charge carriers ?Passive circuit element contains Loss ?Atmospheric attenuation amp。 Interstellar Background Radiation ?Shot(散粒) Noise ?Random motion of charge carriers in Electron tubes amp。 solidstate devices ?Flicker (閃爍) Noise( 1/f Noise) ?In Solidstate amp。 Vacuum(真空) tube ?Quantum(量子) Noise ?In quantized nature of charge carriers amp。 photons(光子) ?Plasma(等離子體) Noise ?In ionized(電離的) gas or sparking electrical contacts(火花放電) ?Noise Voltage and Power of Resistor R R: Resistor at T: Temperature R )(tvn)(tvn0?vk T B RV n 4?Mean Value RMS(均方根) Value )(tvntAvailable Noise Power: Maximum Power can be delivered from Noise Source to load k T BRVRVP nnn ??? 41)2(222220nkTBPS nn ???)(?Twoside Power Spectral Density of thermal noise B +B f理想帶通濾波器 oeNTkB?白噪聲源用一個(gè)等效噪聲溫度來(lái)表征, Te表征元件或系統(tǒng),B是元件或系統(tǒng)的帶寬 任意 2 Noise Temperature amp。 Noise Figure ?Equivalent Noise Temperature: KTs 0