Active filter circuit using gm amplifier, and data read circuit, data write circuit and data reproducing device using the same

摘要

The present invention comprising an active filter having a first gm amplifier, a second gm amplifier equivalent to the first gm amplifier, a band gap power source which applies a constant voltage making use of a band gap voltage to an input of the second gm amplifier and a current-voltage conversion circuit which converts an output current of the second gm amplifier into a voltage, wherein operation currents of the first and second gm amplifiers are controlled depending on the output voltage of the current-voltage conversion circuit.