In one example, the method includes forming a patterned hard mask feature above a layer of gate electrode material, the hard mask feature having a photoresist feature formed thereabove and the hard mask feature having a critical dimension. The photosensitive cell array includes first and second photosensitive cells 2a and 2b. In addition, the current limiting value computing unit computes a difference between a control voltage value, detected by a second voltage sensor provided at a control line independent of the electric power line, and the above power voltage value, and computes an output gain of which the value is smaller as the difference increases.