| 摘要 |
PURPOSE:To obtain a bias voltage having superior precision of a well region by a method wherein an output voltage outputted from a stabilizing voltage circuit and an output voltage regulating circuit is supplied to the well region as the bias voltage through an amplifying circuit. CONSTITUTION:A stabilizing voltage circuit 21 is connected to an output voltage regulating circuit 23 through a line 22. Output of the stabilizing voltage circuit is connected to the input terminal of an amplifying circuit 26 through lines 24, 25. Output of the amplifying circuit 26 is connected to a bias terminal 29 for a CODEC, and used as a stabilizing voltage for the CODEC. While, the bias circuit of a well region is connected to the input terminal of an amplifying circuit 28 through the lines 24, 27. Output of the amplifying circuit 28 is connected to the bias terminal 30 of a well region. After an output voltage is regulated according to the stabilizing voltage circuit 21 and the output voltage regulating circuit 23, applied to the input terminal of the amplifying circuit 26. Accordingly, the voltage value of superior precision can be obtained as the output voltage of the bias terminal 29, and a variation of the threshold voltage according to the substrate effect of an MOS transistor in the well region can be suppressed. |
