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→Need of LNA
=== Need of LNA ===
[[File:Amplifiers5.png|framethumb|thumb500px|RF front end. Image reproduced from [https://commons.wikimedia.org/wiki/File:Superheterodyne_receiver_block_diagram_2.svg here]]]
The signal received by the antenna has a lot of noise. The signal is very close to noise level and any degradation of SNR of the signal will make the signal level go below the noise floor. This will cause the signal to be lost and we can’t get the data from the signal. As we from the above formula the NF of the system is mainly determined by NF of the first device if the gain is very high. As LNA is has a very low noise figure and a very high gain, so the noise figure of the system is very low. The arrangement of antenna followed by LNA is called as an active antenna. Thus LNA is one of the most important part of the RF front end.