Rf power detector

[lucasN]

Hello everyone,

In this circuit, what is the importance of a logarithmic amplifier other than achieving a linear dB output? In all the papers, it is stated that it extends the dynamic range. How is that possible? Isn't the dynamic range already defined by the RMS power detector?

 

[BradtheRad]

Applying logarithmic processing has the effect of compressing bandwidth. From one standpoint it reduces peaks to a manageable level, and from another standpoint it raises weak signals in comparison to the noise floor. Audio amplifiers (so goes the electronics explanation) must provide increasing gain by enormous jumps when we ask them to get louder by merely a few decibels. I suppose rf occupies a similar environment where levels are often read in dB.

 

[lucasN]

But isn't the dynamic range already defined by the rms detector?