Variable attenuator device having substantially constant impedance

摘要

An attenuator of the current invention allows the adjustment in attenuation at a constant impedance level. The attenuator includes at least three variable resistors. Two of the three variable resistors have the substantially same linear resistance characteristics and are controlled in a substantially identical manner. One of the three variable resistors has a non-linear resistance characteristic and is controlled concurrently with the above two variable resistors. As a result of the above resistance characteristics and control, the attenuation is adjusted with respect to the resistance while impedance is maintained at a constant level.