Superheterodyne Receiver

A superheterodyne receiver is a radio receiver architecture that converts an incoming RF signal to a fixed intermediate frequency (IF) by mixing it with a tunable local oscillator (LO). Tuning is accomplished by adjusting $f_{LO}$, keeping $f_{IF}$ fixed, which allows the bandpass filter to be narrow and highly selective regardless of the tuned frequency.

The main stages are:

1. Antenna
2. Low-noise amplifier (LNA)
3. Mixer: produces $f_{IF}=|f_{RF}-f_{LO}|$
4. IF Filter and amplifier
5. ADC / demodulator