| 摘要 |
A variable attenuator which can sequentially control attenuation effectively and has a small variation in manufacturing, is provided. The variable attenuator has a first signal input terminal; a first signal output terminal; a first control terminal receiving a control voltage; an analog/digital converter converting the control voltage to M (M is a positive integer of 2 or more) control signals; and N (N is a positive integer satisfying N>=M) variable impedance elements which are connected in parallel and/or in series between the first signal input terminal and the first signal output terminal, and each impedance of which is varied by either one of the control signals.
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