| 摘要 |
PURPOSE:To obtain an operational amplifier of low current consumption by controlling a first current source by a first bias circuit so that the mutual conductance of a pair of input transistors TRs in a differential amplifying part is fixed and controlling a second current source by a second bias circuit so that the mutual conductance of an output TR in an output amplifying part is fixed. CONSTITUTION:This amplifier consists of the differential amplifying part consisting of a first current source Q16 and the pair of TRs, the output amplifying part consisting of a second current source Q17 and an output TR Q18 to which the output signal of the differential amplifying part is inputted, and a bias circuit which controls the first current source and the second current source, and this bias circuit consists of a first bias circuit 10 which controls the first current source to fix the mutual conductance of the pair of TRs and a second bias circuit 20 which controls the second, current source to fix the mutual conductance of the output TR. Thus, an unnecessary current more than necessary to realize a required frequency characteristic is eliminated to obtain the operational amplifier of low current consumption. |
