Drop, droop and roll-off

Updated June 10, 2007

Click here to go to our slang dictionary

New for June 2007! No, we're not talking about fire safety (stop, drop and roll!) This page seems almost unnecessary. Unless you've been to a design review with technical presentations by managers, marketing types or other idiots.

Drop, droop and roll-off are words used to describe phenomena such as voltage or power, with respect to something else. Usually when that phenomenon is falling below a lower specification limit. Many engineers don't analyze the combined effects of drop, droop and roll-off when they look at design margin.

Droop is used when you are referring to a slope with respect to time. Let's put this in a practice sentence...

The charge storage capacitor is too small and we're getting excessive voltage droop over the 20 mirosecond pulse.

Drop is used when you are referring to a slope against distance. Let's put this in a practice sentence...

The voltage drop along that drain bias line is killing the output power of our transmitter.

Roll-off is used when you are referring to a slope with respect to frequency. Let's put this in a practice sentence...

That damn TriQuint amplifier has a gain roll-off right at the edge of our frequency band.

OK, now does everyone get it?