Semiconductor integrated circuit device having an object circuit to which output voltages of the sub- and main booster circuits are applied

A semiconductor integrated circuit device comprising:

• main booster means for stepping up a power source voltage;
• sub-booster means for stepping up an output voltage of said main booster means;
• an object circuit to which the output voltages of said main booster means and said sub-booster means are applied, said object circuit including an input stage MOS transistor whose one end is connected to an output terminal of said main booster means and whose gate is connected to an output terminal of said sub-booster means,
• said sub-booster means and said object circuit being adapted to apply through another end of said input stage MOS transistor the output voltage of said main booster means not reduced by the threshold voltage of said input stage MOS transistor;
• and
• selection means for selectively applying the output voltage of said main booster means to said object circuit by selectively driving said sub-booster means when a plurality of selection signals are applied to said selection means.