RF front end

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RF front end is a generic term for everything in a receiver that sits between the antenna and the intermediate frequency (IF) stage.

For most super-heterodyne architectures, this part of the receive chain consists of:

• A matching circuit to allow all the received energy from the antenna to get to the next stage;
• A 'gentle' band-pass filter (BPF) to knock down out-of-band jammers;
• Another matching circuit at the input of the low-noise amplifier (LNA);
• The LNA itself — its primary responsibility is to set the receive sensitivity of the receiver, by offering high gain; and very low noise figure (NF);
• Another matching network between the LNA output and the receive (RX) mixer (downconverter);
• The RX mixer itself.