MOS-FET AMPLIFIER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide an MOS-FET amplifier circuit with sufficient amplifying functions by keeping the drain current of an MOS-FET for amplification optimal so as not to be changed over aging. SOLUTION: The MOS-FET amplifier circuit 101 has a control part 30 which comprises a CPU 32 and stores in a ROM 33 the change LS over aging in a voltage between a gate and a source when fixing the drain current of the MOS-FET for amplification for amplifying an input signal by means of an MOS-FET 1 for amplification to set an operating point by the drain current, reads the stored voltage between the gate and the source out of the ROM 33 corresponding to the lapse of time after operation measured by a timer 31, applies D/A conversion to the read voltage by a D/A converter 34 and applies it between the gate and source of the MOS-FET 1 for amplification.