Semiconductor device reducing leakage current of transistor

1. A semiconductor device comprising:

a first transistor having a control electrode coupled to an input node, a first conductive electrode coupled to an output node and a first power supply line, and a second conductive electrode coupled to a second power supply line; and

second to fourth transistors each having a control electrode coupled to said input node, a first conductive electrode coupled to said output node and said first power supply line, a second conductive electrode coupled to said second power supply line, and a well corresponding to a back gate and having a changeable potential,

said second to fourth transistors being substantially equal in size to said first transistor, wherein

said first power supply line and said second power supply line are arranged while being spaced away from each other,

said first transistor and said second transistor are arranged side by side between said first power supply line and said second power supply line in an extending direction of said first power supply line and said second power supply line, and

said third transistor and said fourth transistor are arranged side by side in the extending direction of said first power supply line and said second power supply line on a side opposite to said first transistor and said second transistor with respect to said first power supply line.

2. The semiconductor device according to claim 1 , wherein

said well of each of said third and fourth transistors is coupled to a back gate power supply line to which a changeable voltage is supplied,

a plurality of regions each including said first and second power supply lines and said first to fourth transistors are arranged in an arranging direction of said first power supply line and said second power supply line,

said well of said second transistor in one of said adjoining regions is coupled to at least any one of said well of said third transistor and said well of said fourth transistor in the other one of said adjoining regions.

3. The semiconductor device according to claim 1 , wherein

said back gate power supply line is arranged so as to extend in the arranging direction of said first power supply line and said second power supply line.

4. The semiconductor device according to claim 1 , wherein

each of said first to fourth transistors is of a first conduction type,

said semiconductor device further comprising:

a second conduction type fifth transistor having a control electrode coupled to said input node,

said fifth transistor being connected between said first conductive electrode of said first transistor and said first power supply line and being substantially equal in size to said first transistor; and

second conduction type sixth to eighth transistors each having a control electrode coupled to said input node, and a well corresponding to a back gate and having a changeable potential,

said sixth to eighth transistors being connected between said first conductive electrode of each of said second to fourth transistors and said first power supply line and being substantially equal in size to said first transistor, wherein

said fifth transistor and said sixth transistor are arranged side by side between each of said first and second transistors and said first power supply line in the extending direction of said first power supply line and said second power supply line, and

said seventh transistor and said eighth transistor are arranged side by side between each of said third and fourth transistors and said first power supply line in the extending direction of said first power supply line and said second power supply line.