Amplification vs. Attenuation: Understanding the Difference

This page explains the difference between amplification and attenuation, two fundamental concepts in radio frequency (RF) engineering. Essentially, amplification refers to power gain, while attenuation refers to power loss. These terms are most often associated with RF amplifiers and RF attenuators, respectively.

Amplification

Amplification of an RF signal

When an RF signal passes through an RF amplifier, its amplitude (i.e., magnitude) is increased or boosted. This process is known as amplification. Figure 1 (above) illustrates this concept.

Amplification is typically measured in decibels (dB). The amount of amplification provided by the RF amplifier is quantified as power gain. Gain is expressed as the ratio of output power (Pout) to input power (Pin). The formula for power gain in dB is:

Power Gain (dB) = 10 Log (Pout/Pin)

Attenuation

Attenuation of an RF signal

Conversely, when an RF signal passes through an RF attenuator, any passive device, or even a cable, its amplitude is reduced or diluted. This is known as attenuation. Figure 2 (above) visually represents attenuation.

Like amplification, attenuation is also measured in decibels (dB). The amount of attenuation caused by the passive device (a “lossy” device) is called power loss. Power loss (also known as insertion loss) is expressed as the ratio of input power (Pin) to output power (Pout). The formula for power loss in dB is:

Power Loss (dB) = 10 Log (Pin/Pout)

Key Takeaway

From the definitions and formulas above, it’s clear that amplification is essentially the reverse of attenuation.