© 2008 The McGraw-Hill Companies
9-2: Superheterodyne Receivers
The antenna picks up the weak radio signal and feeds it to the RF amplifier, also called a low-noise amplifier (LNA).
RF amplifiers provide some initial gain and selectivity and are sometimes called preselectors.
Tuned circuits help select the frequency range in which the signal resides.
RF amplifiers minimize oscillator radiation.
Bipolar and FETs can be used as RF amplifiers.