• In all the Power Amplifiers, the output level is a "compressive " or "saturating" function of the input level. The gain of the Power Amplifier approaches zero for sufficiently high input levels. In RF circuits this effect is quantfied by the “1 dB compression point”, defined as the input signal level that causes the small-signal gain to drop by 1dB. This can be plotted in a log-log scale vs input level.