| 摘要 |
PURPOSE:To decrease the effect of bias power supply output fluctuation on an output current by providing a bias power supply which drives the 1st transistor (TR) at the saturated region and drives the 2nd TR at the triode region and using a current flowing to a non-control electrode of a TR series circuit as an output. CONSTITUTION:When an AC signal source 19 is operative and the gate potential of the 1st TR14 is fluctuated in increasing direction, the drain current also increases. Since the drain current of the 2nd TR15 is equal to the drain current of the 1st TR14, the drain current of the 2nd TR15 is increased. Since the 2nd TR15 is operated in the triode region, when the drain current increases, the drain-source voltage is increased. As a result, the gate-source voltage is decreased in the 1st TR14, and then the drain current is decreased. Even when the gate potential of the 1st TR14 gets higher, the drain current of the TR14 is not changed largely and the current flowing to the output terminal 18 is not changed largely. Thus, the effect of bias power supply output fluctuation on the output current is reduced.
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