Variable gain differential amplifier, and variable degeneration impedance control device and method for use in the same

摘要

Disclosed are a variable gain differential amplifier, and variable degeneration impedance control device and method for use in the variable gain differential amplifier, which can adjust an amplification gain and ensure linearity. A DC level of a differential signal to be amplified by the amplifier is adjusted according to a control signal to adjust a gain of the amplifier, and the impedance of a variable degeneration impedance part is adjusted according to the differential signal of which the DC level is adjusted. That is, the gain of the differential amplifier is adjusted and the linearity is ensured by varying the impedance of the variable degeneration impedance part using the differential input signal of which the DC level is adjusted.