Printing element substrate and printhead

A component substrate and the printhead, the substrate comprising: a printing element; switching element driving signal for said printing element based on the control input; a first current source for generating a predetermined current; a second current source for generating a current based on the input voltage; and a current generating circuit, a current through the second current source a current generated by the current generated by the first current source obtained by adding the amplified signal to generate the control, and then by the first current source generating a current control signal to generate the amplification.