Semiconductor device comprising a photoelectric current amplifier

A semiconductor device comprising:

• a current mirror circuit comprising a first transistor and a second transistor which are connected to each other so that a common potential is applied to each gate electrode;
• a photodiode of which a first terminal is connected to a power supply and a second terminal is connected to one of a source region and a drain region of the first transistor and a gate electrode of the first transistor;
• and
• a switch which is inserted in series between the first terminal of the photodiode and one of a source region and a drain region of the second transistor,
• wherein the switch is switched on and off in accordance with intensity of light received by the photodiode.

A semiconductor device comprising:

• a current mirror circuit comprising a first transistor and a second transistor which are connected to each other so that a common potential is applied to each gate electrode;
• a photodiode of which a first terminal is connected to a power supply and a second terminal is connected to one of source region and a drain region of the first transistor and the gate electrode of the first transistor;
• and
• a switch which is inserted in series between the first terminal of the photodiode and one of a source region and a drain region of the second transistor,
• wherein the switch is switched off when intensity of light received by the photodiode is higher than a predetermined value, and
• wherein the switch is switched on when intensity of light received by the photodiode is lower than the predetermined value.