to the third terminal no3 the third n channel transistor nmo3 in the first control circuit 14 in the control signal control means in accordance with the present invention may have a plurality of n channel transistors nmo31 to nmo3n connected in series the temporal coefficient of variation of the control signal n2 can be lowered by connecting a plurality of transistors in series and determined by changing the number of transistors connected particular elements of the second control circuit 15 in accordance with the present invention will be described below the second control circuit 15 in the control signal control means 10 in accordance with the present invention comprises a first p channel transistor pmo1 having a gate thereof connected to a first terminal no1 a first source or drain 12 thereof connected to a fifth terminal no5 and a second source or drain 13 thereof connected to the third terminal no3 a second p channel transistor pmo2 having a gate thereof connected to a sixth terminal no6 a first source or drain 14 thereof connected to a high voltage line v dd 2 and a second source or drain 15 thereof connected to a fifth terminal no5 a third p channel transistor pmo3 having a gate connected to the seventh terminal no7 a first source or drain 16 thereof.