A tuned amplifier operates over a band of frequencies centered on a resonant frequency. Its two main requirements are to provide high gain and good selectivity.
We have several applications in telecommunications systems where it is necessary to amplify a narrow band of frequencies centred on one frequency. A typical example is shown in the frequency-modulated transmitter illustrated below:
In this case, the radio frequency (RF) amplifier is used to increase the amplitude of the oscillator output, while the frequency tripler stages are used to increase the transmitted frequency to 104.5 MHz. Both these stages are forms of tuned amplifier.
Related: The Basic Principle of Operation of an Oscillator
The applications of tuned amplifiers include:
- Intermediate Frequency (IF) amplifier in a satellite transponder.
- IF amplifier in a Superheterodyne receiver.
- RF amplifiers in receivers.
- Wide-band tuned amplifiers for video amplification.
- UHF-radio relay systems.
- Wide-band tuned amplifiers for Y-amplifiers in oscilloscope.
You can also read: The Fundamentals of Oscillators in Communication Systems
