Patent ID: 7876173

Claim:
A signal output device, comprising: an amplitude changer that changes an amplitude of an input signal, and controls a ratio of a change of the amplitude based on a control signal; a discrete attenuator that outputs an output signal obtained by attenuating an output from the amplitude changer while discretely setting an amount of the attenuation; a measurement result changer that changes a measurement result of the output signal; a control signal setter that sets the control signal based on an output from the measurement result changer and a target value of the output signal; an attenuation setter that sets the amount of the attenuation according to a frequency of the input signal; and a change setter that sets an amount of a change provided by the measurement result changer based on a difference between an ideal amount of the attenuation which is an amount of an attenuation proper for the output signal to be close to the target value and the amount of the attenuation set by the discrete attenuator.