Gain compression
![Power transfer curves for an amplifier with a gain of 3 (4.77 dB). The green curve represents an ideal amplifier in which the output power is equal to three times the input power. The red curve represents a typical amplifier which can deliver the gain only up to a certain power level before it hits saturation. Gain compression is the difference between the green curve and the red curve.](/Images/godic/202501/14/Amplifier_Compression2528.gif")
Gain compression is a reduction in 'differential' or 'slope' gain caused by nonlinearity of the transfer function of the amplifying device. This nonlinearity may be caused by heat due to power dissipation, or by overdriving the active device beyond its linear region. It is a large signal phenomenon of circuits.