RF Demystified: What is an RF Attenuator? (Download)
The attenuator is a control component, the main function of which is to reduce the strength of the signal passing through it. This type of component is generally used to balance signal levels in the signal chain, to extend the dynamic range of a system; provide impedance matching; and implement various calibration techniques in the end application design.
From the key functional perspective, attenuators can be classified as fixed attenuators with an unchanging level of attenuation and variable attenuators with an adjustable level of attenuation. Depending on the form of attenuation control supported by variable attenuators, they can in turn be further classified as voltage variable attenuators (VVAs), featuring analog control, and digital step attenuators (DSAs) that are controlled digitally.