Signal generation device, liquid ejection device, and signal generation method capable of suppressing extension of liquid ejection interval

A signal generation device, comprising:

• a first signal generation portion configured to, based on a reference signal that includes a plurality of rectangular single-wave signals that are output at predetermined specific periods, generate an original common signal in which the rise times of the two or more of the single-wave signals included in the reference signal are extended so that they are different from each other, and the fall timing of one or more of the single-wave signals included in the reference signal is shifted;
• an amplifying portion configured to amplify the original common signal;
• and
• a second signal generating portion configured to generate a drive signal to be input to a piezoelectric element that ejects liquid from a nozzle by extracting a rising edge of any one of the single-wave signals, the rise time of which is extended, from the original common signal amplified by the amplifying portion, maintaining a signal level changed by extracting the rising edge of the single-wave signal, and extracting a falling edge of a single-wave signal occurring later than the single-wave signal.