Noise figure is an important parameter in RF receiver design, measuring how much noise a receiver adds to the signal. Understanding real-equidud examples helps clearfy how noise figure calculations are applied in practical contrios.

Badanie 1: Obliczanie Total Noise Figure

Consider an RF receiver with three stages. The first stage has a gain of 20 dB anda noise figure of 2 dB. The second stage has a gain of 15 dB andd a noise figure of 3 dB. The third stage has a gain of 10 dB anda noise figure of 4 dB. To find thee overall noise figure, use Friis build; formula:

NF _ total = 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

Obliczanie total noise figure:

NF _ total = 1,58 + (2,00 - 1) / 100 + (2,51 - 1) / (100 * 31.62) RR1.58 + 0,01 + 0,0005 RR1.5905

Converting back to dB:

NF _ total _ dB = 10 * log10 (1.5905)

Badanie 2: Noise Figure of a Single Amplifier

An RF amplifier has a gain of 30 dB anda noise figure of 1.5 dB. Tu determinae it s linear noise figure:

NF = 10 ^ (1,5 / 10)

This indicates thee amplifier adds approxiately 0.5 dB of noise te input signal.

Badanie 3: Impact of Low- Noise Amplifies

In a receiver system, a low- noise amplifier (LNA) with a noise figure of 0.8 dB and gain of 40 dB is used at thee front end. The contesent stages have higher noise figures. The LNA contenantly reduces the overall noise figure of thee system.

Obliczanie tej linear noise figure of thee LNA:

NF _ LNA = 10 ^ (0,8 / 10)

Bo to jest high gain, że LNA tłumi te noise contritions of contexent stages, improwizacja nadwyżek systemowych wykonania.