Solid-state image sensor output MOSFET amplifier with MOSFET load

A solid-state imager comprising:

• a substrate layer of a first conductivity type in a semiconductor substrate;
• first and second wells of a second conductivity type formed in said substrate layer, said first and second wells both extending into said substrate from a top surface of said substrate;
• a pair of first drain and first source regions of the first conductivity type formed in the first well region;
• a pair of second drain and second source regions of the first conductivity type formed in the second well region;
• a first insulated gate electrode formed on said top surface of said substrate, said first gate electrode forming a drive side MOS transistor with said first drain and source regions;
• and
• a second insulated gate electrode formed on said top surface of said substrate, said second gate electrode forming a load side MOS transistor with said second drain and source regions, said drive side MOS transistor and said load side MOS transistor being connected to form a floating diffusion type output amplifier of said solid-state imager;
• wherein said first well is deeper from said top surface of said substrate than said second well.