Patent ID: 7466196

Claim:
A detector for automatic gain control (AGC), which is used for a variable gain amplifier (VGA) including at least one VGA cell, the detector comprising: first and second transistors having drains connected in common to a power supply voltage and sources connected in common to a first node, and driven in response to a non-inverting output voltage and an inverting output voltage of the VGA cell, respectively; a first current source connected between the sources of the first and second transistors and a ground voltage to supply a predetermined current; a third transistor having a drain and a source connected to the power supply voltage and a second node, respectively, and driven in response to a pre-set reference voltage; a second current source connected to the source of the third transistor and the ground voltage to supply a predetermined current; and a comparator having a non-inverting input terminal and an inverting input terminal connected to the first and second nodes, respectively, and comparing a peak voltage from the first node with a reference voltage from the second node to output a control voltage with a predetermined level to the VGA cell based on the comparison result.