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9-6: Typical Receiver Circuits
RF Input Amplifier
The RF amplifier, also called a low-noise amplifier (LNA), processes the very weak input signals, increasing their amplitude prior to mixing.
Low-noise components are used to ensure a sufficiently high S/N ratio.
Selectivity should be such that it effectively eliminates images.
The RF amplifier is typically a class A circuit that can be configured with bipolar or field-effect transistors.