| 摘要 |
PURPOSE:To drive a MOSFET analog circuit at an extremely low noise level by setting a working range so that the drain-source voltage of a MOSFET is smaller than the value with which the impact ionization is started within a channel. CONSTITUTION:The working range of a MOSFET is set so that the drain-source voltage of the MOSFET is smaller than the value with which the impact ionization is started within a channel. For instance, the working range must be set at the inside of the boundary shown by straight lines 3 and 4 so that no impact ionization is produced at both sides of transistors TRs TR T1 and T2 of a source follower using the buried channel MOSFETs T1 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 the inside of each boundary of the buried channel mode conditions (1) and (2), the conditions (3) and (4) for avoiding impact ionization and the weak inversion avoiding conditions (5) respectively.
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