To reduce a variation in the electrical characteristics of a transistor. A potential generated by a voltage converter circuit is applied to a back gate of a transistor included in a voltage conversion block. Since the back gate of the transistor is not in a floating state, a current flowing through the back channel can be controlled so as to reduce a variation in the electrical characteristics of the transistor. Further, a transistor with low off-state current is used as the transistor included in the voltage conversion block, whereby storage of the output potential is controlled.

A system having an integrated circuit (IC) device can include a die formed on a semiconductor substrate and having a plurality of first wells formed therein, the first wells being doped to at least a first conductivity type; a global network configured to supply a first global body bias voltage to the first wells; and a first bias circuit corresponding to each first well and configured to generate a first local body bias for its well having a smaller setting voltage than the first global body bias voltage; wherein at least one of the first wells is coupled to a transistor having a strong body coefficient formed therein, which transistor may be a transistor having a highly doped region formed below a substantially undoped channel, the highly doped region having a dopant concentration greater than that the corresponding well.

A system having an integrated circuit (IC) device can include a die formed on a semiconductor substrate and having a plurality of first wells formed therein, the first wells being doped to at least a first conductivity type; a global network configured to supply a first global body bias voltage to the first wells; and a first bias circuit corresponding to each first well and configured to generate a first local body bias for its well having a smaller setting voltage than the first global body bias voltage; wherein at least one of the first wells is coupled to a transistor having a strong body coefficient formed therein, which transistor may be a transistor having a highly doped region formed below a substantially undoped channel, the highly doped region having a dopant concentration greater than that the corresponding well.