| 摘要 |
PURPOSE:To drive a MOSFET analog circuit at an extremely low noise level by setting the working range so that the gate-source voltage of a MOSFET is smaller than the value with which the weak inversion is started on the surface of a channel. CONSTITUTION:The working range of a MOSFET is set so that the gate-source voltage of the MOSFET is smaller than the value with which the weak inversion is started on the surface of a channel. For instance, the working range must be limited inside the boundary shown by an action line 5(VGL=VG(Inv)) in order to avoid the weak inversion produced at the source side of the MOSFET at the side of a transistor TRT2 of a source follower using the buried channel MOSFETT1 and T2 as shown in the diagram. Therefore the working range of a low noise level is limited within an area shown by oblique lines and at the inside of each boundary of conditions (1) and (2) of a buried channel mode, the impact ionization avoiding conditions (3) and (4) and the weak inversion avoiding conditions (5) respectively.
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