| 摘要 |
PURPOSE:To make a good operation possible without requiring a special voltage control circuit by operating two PIN diodes as a variable attenuator in the state where they have always the same resistance value and constituting a DC current passage to flow the same control current to them. CONSTITUTION:A series circuit of a resistance 26 having the same resistance value as the circuit impedance and a PIN diode 14 is connected between an input terminal 11 and an output terminal 12, and a series circuit of 1/4 wave length lines 27 and 28 having a sq. rt. 2-fold characteristic impedance of the circuit impedance is connected in parallel to said series circuit, and the connection point of lines 27 and 28 is grounded through a PIN diode 17. If the current flowed to diodes 14 and 17 is zero and the resistance value is infinite, the quan tity of attenuation is zero. If the resistance value of diodes 14 and 17 is equal to the circuit impedance Z0, they have the same constitution as a Wilkinson voltage distributor, and terminals 11 and 12 are isolation ports to each other, and the quantity of attenuation is infinite. That is, the quantity of attenuation is changed with one control current. |
