a substrate;

a first gate extending along a longitudinal direction over the substrate, the first gate comprising a gate electrode, wherein the first gate has a first length along the longitudinal direction;

a second gate over the substrate and apart from the first gate, wherein the second gate has a second length along the longitudinal direction and a second width along a horizontal direction orthogonal to the longitudinal direction, wherein the second length is greater than the second width, and the second length substantially equals the first length;

a source region of a first conductivity type in the substrate, aligning to an edge in proximity to a side of the first gate, having a source length substantially equals the first length;

a P-type well surrounding the source region;

a drain region of the first conductivity type in the substrate, and having a drain length substantially equals the first length;

an N-type well surrounding the drain region, wherein the N-type well has an N-well length along the longitudinal direction, the N-well length is greater than the second length of the second gate, the second gate is entirely within a vertical projection area of the N-type well, and a bottom surface of the P-type well and a bottom surface of the N-type well are substantially at a same depth from the first gate;

wherein the drain length is measured from one edge of the drain region to an opposite edge of the drain region along the longitudinal direction;

the source length is measured from one edge of the source region to an opposite edge of the source region along the longitudinal direction;

the second length is measured from one side of the second gate to an opposite side of the second gate across the longitudinal direction;

the second width is measured from one edge of the second gate to an opposite edge of the second gate across the horizontal direction; and

the N-well length is measured from one side of the N-type well to an opposite side of the N-type well across the longitudinal direction.