Low-Noise/High-Gain Question

[candycane]

What is ment by this.

 

[dahut]

This means you can increase circuit gain (amplification) without an attendant increase in circuit noise.

When you amplify any point in a circuit, you amplify the circuit noise found in that circuit. ALL circuits generate their own noise, and the more you stage-amplify circuits, the more the noise increases.
But modern, solid state electronics, have minimized this. Today's low power, low noise circuits are extremely quiet, compared to the older designs.

Notice I said low power?

This is because these circuits actually consume very little power, which is the main reason why they are so quiet. This means they can be given exponentially higher signal gain within the circuits, without incurring the penalty of noisiness.
Then in the latter stages, power amplification is done, so there is very little noise to be amplified and make things ugly.