Patent ID: 7557657

Claim:
A variable gain amplifier, comprising: a differential amplification unit amplifying and outputting a difference between a first input signal and a second input signal inputted via a first input terminal and a second input terminal, respectively, according to a first bias current of the first input terminal and second input terminal, to a first output terminal and a second output terminal; a diode-connected load unit comprising loads diode-connected to the first output terminal and second output terminal, respectively, the loads receiving a second bias current; and a gain control unit controlling a gain between the input terminals and the output terminals of the differential amplification unit by controlling the size of the first bias current and second bias current; wherein the diode-connected load unit comprises: a fifth n-channel metal-oxide semiconductor transistor having a drain connected to the first output terminal and a gate mutually connected to the drain; and a sixth n-channel metal-oxide semiconductor transistor having a drain connected to the second output terminal and a gate mutually connected to the drain, wherein sources of the fifth n-channel metal-oxide semiconductor transistor and sixth n-channel metal-oxide semiconductor transistor are connected to each other, and the second bias current is provided to the sources of the fifth and sixth n-channel metal-oxide semiconductor transistors.