| 摘要 |
PURPOSE:To generate a stable output voltage which is not affected by variation in source voltage by adjusting the gate voltage of MOS transistors (TR) as the load resistance of a source follower through a bias voltage circuit so that variation in output voltage with the source voltage is canceled. CONSTITUTION:A depletion type TR is used as a Tr2 of a load bias circuit and its operation point is set in a nonsaturation region (triode region). An enhancement type TR is used as a Tr1 of the load bias circuit, and the gate is connected to the drain, allowing the TR to operate in a saturation region. The Tr1 and Tr2 divide the source voltage VDD and the divided voltage Vb is outputted from the connection point A and supplied to gates of the Tr2, Tr5, and Tr7. The Tr2 is in the nonsaturation triode region, so the voltage Vb at the output terminal A rises as the source voltage VDD rises, and consequently the gate voltage of the Tr5 and Tr7 rises to increase the conductivity, so that the output voltage Vout does not rise with the source voltage VDD. |
