| 摘要 |
PURPOSE: To reduce the number of components and layout area and to provide a step attenuator unit with a simple construction by sharing transistors(TRs) arranged on the shunt side. CONSTITUTION: When an FET 102 is turned off and an FET 104 is turned on by an external signal S, an attenuator unit 100 operates as aπtype attenuator. A signal inputted to a terminal 118 is attenuated in accordance with the quantity of attenuation determined by resistance 106, 108, 110 and outputted to a terminal 120. when the FET 102 is turned on and the FET 104 is turned off by the signal S, a conductive state is formed between the terminals 118, 120 and the signal inputted to the terminal 118 is outputted to the terminal 120 without being attenuated. Thereby the quantity of attenuation between the terminals 118, 120 can be set up stepwise and an attenuator unit with simple constitution reducing one FET from the number of FETs on the shunt side can be attained.
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