Capacitor cell and structure thereof

A capacitor cell, comprising:

• a first PMOS transistor coupled between a power supply and a first node, having a source directly connected to the power supply, a drain directly connected to the first node, and a gate directly connected to a second node;
• a first NMOS transistor coupled between a ground and the second node, having a source directly connected to the ground, a drain directly connected to the second node, and a gate directly connected to the first node;
• a second PMOS transistor coupled between the first node and the second node, having a source directly connected to the second node, a drain directly connected to the first node, and a gate directly connected to the second node;
• and
• a second NMOS transistor coupled between the first node and the ground, having a source directly connected to the ground, a drain directly connected to the first node, and a gate directly connected to the first node,
• wherein the first and second PMOS transistors on an N-type well region and the first and second NMOS transistors on a P-type well region are arranged in the same row,
• wherein the second NMOS transistor is formed by a third NMOS transistor and a fourth NMOS transistor coupled in parallel, wherein the source of the first NMOS transistor and a source of the third NMOS transistor share a first N+ doped region in the P-type well region, and drains of the third and fourth NMOS transistors share a second N+ doped region in the P-type well region.

A capacitor cell structure, comprising:

• a semiconductor substrate;
• an N-type well region on the semiconductor substrate;
• a P-type well region on the semiconductor substrate, wherein the P-type well region is in contact with the N-type well region;
• a first P+ doped region in the N-type well region and coupled to a power line;
• a second P+ doped region in the N-type well region;
• a first active region between the first and second P+ doped regions in the N-type well region;
• a first N+ doped region in the P-type well region and coupled to a ground;
• a second N+ doped region in the P-type well region and coupled to the first active region;
• a second active region between the first and second N+ doped regions in the P-type well region and coupled to the second P+ doped region;
• a third N+ doped region in the P-type well region and coupled to the second active region;
• a fourth N+ doped region in the N-type well region and coupled to the power line;
• a third P+ doped region in the P-type well region and coupled to the ground;
• a first isolation region between the first P+ doped region and the fourth N+ doped region;
• a second isolation region between the third N+ doped region and the third P+ doped;
• and
• a third isolation region between the P-type well region and the N-type well region.