Patent ID: 8350619

Claim:
A filter circuit comprising: a current mirror circuit including: a first transistor, a second transistor, and a third transistor having a same channel polarity, a drain of the first transistor being connected to a source of the second transistor, a drain of the second transistor being connected to a gate of the first transistor and a gate of the third transistor; a first capacitive element having a first end connected to the gate of the first transistor and a second end connected to a fixed potential; and a second capacitive element having a first end connected to the drain of the first transistor and a second end connected to the fixed potential; a first bias current supplying circuit configured to supply a bias current to each of the first and second transistors; an input terminal connected to at least one of the drain and the gate of the first transistor; and an output terminal configured to extract a signal from a drain current of the third transistor.