Semiconductor device with leakage current compensating circuit

1. A semiconductor device comprising:

a current mirror circuit comprising a plurality of transistors;

a current source configured to supply a constant reference current to said current mirror circuit through a node; and

a current compensating circuit configured to supply a compensation current to said node to compensate for at least a part of gate leakage currents of said plurality of transistors,

wherein said current compensating circuit comprises:

a compensating device having an electrode of an area substantially equal to a summation of gate areas of said plurality of transistors, and configured to generate said compensation current based on a predetermined voltage applied to the electrode of said compensating device.

2. The semiconductor device according to claim 1 , wherein said compensating device comprises:

a MOS transistor having a gate as said electrode, and a source and a drain connected to each other and connected to said node.

3. The semiconductor device according to claim 1 , wherein said predetermined voltage is a power supply voltage.

4. The semiconductor device according to claim 1 , wherein said current compensating circuit further comprises:

a voltage adjusting circuit comprising first and second resistances connected in series and configured to generate an adjustment bias voltage from a power supply voltage by said first and second resistances and to supply said adjustment bias voltage to said compensating device as said predetermined voltage.

5. A semiconductor device comprising:

a current mirror circuit comprising a plurality of transistors;

a current source configured to supply a constant reference current to said current mirror circuit through a node; and

a compensating circuit configured to supply a compensation current to said node to compensate for at least a part of gate leakage currents of said plurality of transistors,

wherein said compensating circuit comprises:

a current supply circuit; and

a control circuit configured to control said current supply circuit based on an output voltage of said current supply circuit and a reference voltage at a reference node such that said current supply circuit supplies said compensation current to said node.

6. The semiconductor device according to claim 5 , wherein said compensating circuit further comprises:

a reference voltage generating circuit configured to supply a current equal to said constant reference current to said reference node; and

a MOS transistor having a drain connected with said reference node, a gate connected with said drain and a source connected with a ground.

7. The semiconductor device according to claim 5 , wherein said control circuit compares the output voltage of said current supply circuit and the reference voltage at said reference node and controls said current supply circuit based on the comparing result.

8. A method of suppressing gate leakage currents, comprising:

supplying a constant reference current from a current source to a current mirror circuit of a plurality of transistors through a node; and

supplying a compensation current from a compensating circuit to said current mirror circuit through said node to compensate for at least a part of gate leakage currents of said plurality of transistors,

wherein said compensating circuit comprises:

a compensating device having an electrode of an area substantially equal to a summation of gate areas of said plurality of transistors, and

said supplying the compensation current comprises:

generating said compensation current based on a predetermined voltage applied to the electrode of said compensating device.