Voltage supply with low power and leakage current

1. A semiconductor integrated circuit device, comprising:

a circuit block;

a first MOS transistor;

a first power line;

a second power line;

a third power line; and

a drive circuit;

wherein the MOS transistor is connected between the first power line and the second power line,

wherein the circuit block is connected between the second power line and the third power line,

wherein the drive circuit controls a voltage supplied to a gate of the first MOS transistor,

wherein the MOS transistor is off in a standby state,

wherein the MOS transistor is on in an operation state,

wherein during a shift from the standby state to the operation state, the drive circuit changes the voltage supplied to the gate of the first MOS transistor at a first rate, and then, changes the voltage supplied to the gate of the first MOS transistor at a second rate faster than the first rage,

wherein the drive circuit includes a first drive circuit and a second drive circuit,

wherein a driving performance of the first drive circuit is smaller than a driving performance of the second drive circuit, and

wherein an output of the first drive circuit and an output of the second drive circuit are commonly connected to the gate the first MOS transistor.

2. The semiconductor integrated circuit device according to claim 1 :

wherein during the shift from the standby state to the operation state, the second drive circuit drives the gate of the first MOS transistor after the first drive circuit drives the gate of the first MOS transistor to a predetermined voltage level.

3. The semiconductor integrated circuit device according to claim 1 , further comprising:

a request line; and

a potential detector;

wherein the first drive circuit drives the gate of the first MOS transistor when the request line reaches a high level; and

wherein the second drive circuit drives the gate of the first MOS transistor when the potential detector detects that the gate of the first MOS transistor is driven to a predetermined voltage level.

4. The semiconductor integrated circuit device according to claim 3 , further comprising:

a timer; and

a response line;

wherein the response line is driven to a second high level when the timer detects the passage of a predetermined time from the time when the potential detector detects that the gate of the first MOS transistor is driven to the predetermined voltage level.

5. The semiconductor integrated circuit device according to claim 1 , further comprising: a potential detector;

wherein the second drive circuit drives the gate of the first MOS transistor when the potential detector detects that the second power line is driven to a predetermined voltage level.

6. The semiconductor integrated circuit device according to claim 5 , further comprising:

a response line;

wherein the response line is driven to a high level when the potential detector detects that the second power line is driven to the predetermined voltage level.

7. The semiconductor integrated circuit device according to claim 1 , further comprising:

a current source;

wherein the current source is connected between the first power line and the second power line; and

wherein the circuit block comprises a information retention circuit which is a circuit with a volatile information retention function.

8. The semiconductor integrated circuit device according to claim 7 ,

wherein the information retention circuit is either one of a flip-flop or a memory cell array.

9. The semiconductor integrated circuit device according to claim 1 ,

wherein the first MOS transistor is a NMOS transistor, and

wherein a voltage of the first power line is smaller than that of the second power line.

10. A semiconductor integrated circuit device comprising:

a circuit block;

a first MOS transistor;

a first power line;

a second power line;

a third power line; and

a drive circuit,

wherein the first MOS transistor is connected between the first power line and the second power line,

wherein the circuit block is connected between the second power line and the third power line,

wherein the drive controls a voltage supplied to a gate of the first MOS transistor,

wherein the first MOS transistor is off in a standby state,

wherein the first MOS transistor is on in a operation state, and

wherein during a shift from the operation state to the standby state, the drive circuit changes the voltage supplied to the gate of the first MOS transistor at a first rate, and then the drive circuit changes the voltage supplied to the gate of the first MOS transistor at a second rate faster than the first rate.

11. A semiconductor integrated circuit device according to claim 10 ,

wherein the drive circuit includes a first drive circuit and a second drive circuit,

wherein a driving performance of the first drive circuit is smaller than a driving performance of the second drive circuit, and

wherein an output of the first drive circuit and an output of the second drive circuit are commonly connected to the gate of the first MOS transistor.

12. The semiconductor integrated circuit device according to claim 11 :

wherein during the shift from the operation state to the standby state, the second drive circuit drives the gate of the first MOS transistor after the first drive circuit drives the gate of the first MOS transistor to a predetermined voltage level.

13. The semiconductor integrated circuit device according to claim 12 , further comprising:

a request line; and

a potential detector,

wherein the first drive circuit drives a gate of the first MOS transistor when the request line reaches a low level; and

when the second drive circuit drives the gate of the first MOS transistor when the potential detector detects that the gate of the first MOS transistor is driven to the predetermined voltage level.

14. The semiconductor integrated circuit device according to claim 12 , further comprising:

a timer;

a response line; and

a potential director,

wherein the response line is driven to a low level when the timer detects the passage of a predetermined time from the time when the potential detector detects that the gate of the first MOS transistor is driven to the predetermined voltage level.

15. The semiconductor integrated circuit device according to claim 12 , further comprising:

a current source,

wherein the current source is connected between the first power line and the second power line; and

wherein the circuit block comprises a information retention circuit which is a circuit with volatile information retention functions.

16. The semiconductor integrated circuit device according to claim 15 ,

wherein the information retention circuit is either one of a flip-flop or a memory cell array.