| 摘要 |
Transistors tend to have variations in their characteristics according to the precision of patterning or the non-uniformity in thickness of a semiconductor film or a gate insulating film which are laminated in the manufacturing process. In the case of polysilicon transistors, in addition, crystallinities tend to vary according to defects in the direction of crystal growth or the crystal grain boundary. Then the invention is characterized in that a value of signal current which is supplied from a current source circuit having a plurality of current sources arranged in each wiring is set to supply a predetermined signal current by using reference constant current source, and that an electrical connection between the current source and wiring to which the signal current is outputted is changed over in each certain period.
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