| 摘要 |
PURPOSE:To execute a change of a clamp level in a short time by providing a switch element for bypassing a clamping diode in synchronization with the time when changing the clamp level. CONSTITUTION:A switch element 19 is provided in parallel to a clamping diode 4. In this state, a control signal is applied to he switch element 19 from a control terminal 20, by which it is opened and closed in synchronization with the time when changing the clamp level of a clamp bias voltage source 9. Accordingly, the instant that a bias voltage Vs has been switched to a high clamp level from a low clamp level, a charging circuit of a capacitor 3 is formed by synchronizing it, and a voltage of a high clamp level can be transmitted to an output terminal 2 quickly. In this way, a change of the clamp level can be executed in a short time. |
