A CMOS image sensor includes: a substrate containing a potential well stack including: a first p-well, a first n-well disposed below the first p-well, a second p-well disposed below the first n-well, a second n-well disposed below the second p-well, and a third p-well disposed below the second n-well, wherein a first photodiode is formed at the junction between the first p-well and first n-well, a second photodiode is formed at the junction between the first n-well and second p-well, a third photodiode is formed at the junction between the second p-well and the second n-well, and a fourth photodiode is formed at the junction between the second n-well and the third p-well, and each photodiode is disposed at a different respective depth within the substrate; and a plurality of active pixel sensors for converting light received by the photodiodes into electrical charge.