FAQ-Why Isolator is used at output of Amplifier?

This page mentions function of isolator used at output of the Amplifier. It provides links to RF Isolator and RF Amplifier basics.

RF Amplifier function: It is RF device which amplifies input signal to produce amplified signal at its output port.

RF Isolator function: It is RF device which passes signal only in one direction i.e. from input port to the output port.

It prevents signal going in the other direction i.e. from output port to the input port.

rf isolator at amplifier output

To fulfill desired functionality as mentioned, RF isolator has been designed to have low insersion loss and high isolation. The same has been depicted in the top part of figure above.

RF amplifier devices are usually very costly. Due to high isolation of isolator, by using it at the output of amplifier, it prevents reflections to pass to the RF amplifier device. Hence it helps in damaging the amplifier and consecutively saves the cost.
Moreover due to low insertion loss, it does not add more attenuation to the RF signal chain.


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