| 摘要 |
PURPOSE:To provide a variable attenuator which widens a dynamic range, can precisely control an attenuation, and reduces the rate of distortion. CONSTITUTION:PIN diodes D1-D4 are series connected and inserted forward to a signal input/output path. A forward DC current IF is supplied to the diodes Di-D4. This current IF is made into a constant current by a constant current circuit 10 and further controlled by a control voltage Vc. The value of the current IF is switched under the control of a multiplexer 12 as well. A capacitor C2 and a load are parallelly inserted under the control of a transistor TR 1. |
