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Periksa 1: Calculating Total Noise Figure

Konsedeer aun RF recever with three stades. Thefrestotstath has a gaif15dBantnoiveof 20 dB and a noise figureme of 2 dB. The third stape has a gain of 15 dB and a noisecure oures fore tore fresque.

NF _ tatal = NF1 + (NF2 - 1) / G1 + (NF3 - 1) / (G1 * G2)

Converting gains to linear scale:

G1 = 10 ^ (20 / 10) = 100

G2 = 10 ^ (15 / 10) = 31.62

NF1 = 10 ^ (2 / 10) = 1.58

NF2 = 10 ^ (3 / 10) = 2.00

NF3 = 10 ^ (4 / 10) = 2.51

Kalkulating total noise figure:

NF _ tatal = 1.58 + (2.00 - 1) / 100 + (2.51 - 1) / (100 * 31.62) 15.8 + 0.01 + 0.0005 1.5905

Converting back to dB:

NF _ tatal _ dB = 10 * log10 (1.5905) BE 1.01 dB

Periksa 2: Noise Figure of a Single Amplifiir

An RF amplifier has a gain of 30 dB and a noise figureme of 1.5 dB. To decie its linear noise figure:

NF = 10 ^ (1.5 / 10) 1x1

Ini menunjukkan bahwa amplifieh adds mendekati 0.5 dB of noise te inputt signul.

Periksa 3: Impatt of Lower-Noise Amplifiers

Ini adalah sistem penerima, sebuah loft-noise ampfier (LNA) weh sebuah noise figure of 0.8 dB gaid of 40 dB is usuad athe the overl noie figure.

Kalkulating the linear noise figure of the LNA:

NF _ LNA = 10 ^ (0.8 / 10) 13.20

Karena itu adalah high gain, itu adalah suppresses LNA kemudian kontributor of kemudian stades, improving overall systems perforce.