Patent ID: 8164395

Claim:
A signal modulator for generating a pulse signal based on a continuous signal output from an oscillator, the signal modulator comprising: a control signal generator that outputs a first control signal containing an on interval at which a voltage value of the first control signal is high and an off interval at which the voltage value of the first control signal is low; an intermittent multiplier that receives inputs of the first control signal and the continuous signal and multiplies the continuous signal corresponding to the on interval of the first control signal to output the pulse signal; and a control section that detects a level of the pulse signal to generate a second control signal for controlling a level of the continuous signal output from the oscillator and a third control signal for controlling a conversion gain of the intermittent multiplier, wherein the conversion gain of the intermittent multiplier at the on interval of the first control signal is higher than the conversion gain of the intermittent multiplier at the off interval of the first control signal.