VARIABLE GAIN AMPLIFIER

摘要

PURPOSE: A variable gain amplifier is provided to provide a variable gain amplification function to an input signal and thus to have a wide band operation characteristics by a stable current bias. CONSTITUTION: The first unit inputs the first and the second input voltage differentially. The second unit generates various output currents by controlling an amplitude of transconductance according to a control voltage. The third unit generates a mirror type current by inputting the control voltage and the bias voltage differentially, and supplies a stable current to the second unit using the mirror current. And the fourth unit generates an output voltage having a variable gain according to the output current generated by the second unit.