Abstract:
Disclosed is an internal voltage supplier for the memory device, the internal voltage supplier comprising: a first switching means for selecting one of a first voltage generated from an interior of the memory device and a second voltage applied from an exterior of the memory device; and a divider for receiving the first voltage or the second voltage selected by the first switching means and outputting a plurality of internal voltages.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an internal voltage supplier for a memory device, and more particularly to an internal voltage supplier for a memory device which can selectively receive power supply voltages supplied from the interior or exterior of the memory device, so as to provide the selected power supply voltage to the memory device. 
     2. Description of the Prior Art 
     As generally known in the art, a memory device operates by using a driving voltage Vdd applied from an exterior thereof. Recently, semiconductor memory devices have shown a tendency of having high integration and using lower power, so that the voltage level of a driving voltage Vdd applied to the memory device becomes lower and lower. However, when the driving voltage of a memory device is lowered, it is required to change the threshold voltage of a transistor, which consequently deteriorates the operation stability of the memory device. Therefore, it is important in a low-power high-integration memory device to provide stable voltage to the memory device. To this end, the conventional memory device uses an internal high-voltage generator, which is contained in the memory device, to provide a high voltage to an internal circuit requiring the high voltage. 
     However, the conventional memory device has a problem in that it frequently occurs that the voltage level of the high voltage generated from the internal voltage generator greatly changes depending on temperature change or a memory device fabricating process. 
     Also, in the conventional memory device, when an auto-precharge operation requiring the use of a high voltage is performed, it frequently occurs that the voltage level of the high voltage is temporarily dropped, which would cause a malfunction of the memory device. Such problems occur in other internal voltages of the memory device, too. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide an internal voltage supplier for a memory device which can provide stable internal voltage to the memory device. 
     The present invention has an object to provide a device which receives a supply power directly from an exterior in order to generate an internal voltage of a memory device when power used in the memory device increases. 
     In accordance with a first aspect of the present invention in order to accomplish the above objects, there is provided an internal voltage supplier for the memory device, the internal voltage supplier comprising: a first switching means for selecting one of a first voltage generated from an interior of the memory device and a second voltage applied from an exterior of the memory device; and a divider for receiving the first voltage or the second voltage selected by the first switching means and outputting a plurality of internal voltages. 
     Herein, the first switching means is turned on/off by a code signal of a mode register set (MRS) or an extended mode register set (EMRS). 
     Herein, the first voltage and the second voltage have an equal voltage level, and current driving capability obtained with the second voltage is larger than that obtained with the first voltage. 
     Preferably, the internal voltage supplier further comprises a second switching means which selects one of the internal voltages outputted from the divider. Herein, the second switching means is turned on/off by a code signal of the MRS or the EMRS. In addition, it is preferred that the internal voltage supplier further comprises a control signal generation means which outputs a control signal for turning on/off the second switching means, wherein the control signal generation means generates the control signal by decoding the code signal of the MRS or the EMRS. 
     In accordance with a second aspect of the present invention in order to accomplish the above objects, there is provided an internal voltage supplier for the memory device, the internal voltage supplier comprising: a first voltage generation means for generating a first voltage; a second voltage generation means for generating a second voltage; a first switching means for selecting one of the first and second voltages in response to a first control signal; a divider for dividing a voltage selected by the first switching means into a plurality of voltage levels; a second switching means for selecting one of the multiple voltage levels outputted from the divider; and a decoder for generating a second control signal which turns on/off the second switching means on/off. 
     Herein, the first voltage generation means is disposed in the memory device and the second voltage generation means is disposed outside the memory device. 
     Herein, the first control signal is a code signal of a mode register set (MRS) or an extended mode register set (EMRS). 
     Herein, the decoder uses a code signal of the MRS or the EMRS in order to generate the second control signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram illustrating an internal voltage supplier for a memory device according to an embodiment of the present invention; and 
         FIG. 2  is a circuit diagram illustrating a construction of the decoder of the internal voltage supplier for the memory device shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same reference numerals are used to designate the same or similar components, and so repetition of the description on the same or similar components will be omitted. 
       FIG. 1  is a block diagram illustrating an internal voltage supplier for a memory device according to an embodiment of the present invention. 
     The internal voltage supplier for the memory device includes a first and a second voltage generation means  11  and  12 , a switching means  13 , a divider  14 , a decoder  15 , and a switching section  16 . 
     The first voltage generation means  11  is contained in the memory device, amplifies a driving voltage VDD applied to the memory device so as to generate a high voltage V 1  higher than the driving voltage VDD. Herein, it is preferred that the high voltage V 1  has a voltage level equal to or slightly higher than that of a high voltage VPP which is used to active the word lines of the memory device. 
     The second voltage generation means  12  represents a voltage source either contained in an external system connected to the memory device or provided from an external system. The second voltage generation means  12  generates a voltage V 2  having a high current driving power. Herein, it is preferred that the voltage V 2  has the same voltage level as the voltage V 1 . However, it is preferred that the current driving capability obtained with the voltage V 2  is greater than that obtained with the voltage V 1 . That is, it is preferred that the current driving capability of the second voltage generation means is greater than that of the first voltage generation means. With such a construction, the second voltage generation means  12  can provide a stable power to an internal circuit of the memory device. 
     The switching means  13  includes a switch S and performs a switching operation by a control signal A 0 . The switch S is connected to the output node of the first voltage generation means  11  when the control signal A 0  has a low level, and is connected to the output node of the second voltage generation means  12  when the control signal A 0  has a high level. That is, the switching means  13  selects the power supply voltage V 1  of the first voltage generation means  11  when the control signal A 0  has a low level, and selects the power supply voltage V 1  of the second voltage generation means  12  when the control signal A 0  has a high level. Herein, the control signal A 0  represents a logic level of an address A 0  contained in a mode register set (MRS) or in an extended mode register set (EMRS). That is, the switching means  13  can select either the voltage V 1  generated from the first voltage generation means  11  or the voltage V 2  generated from the second voltage generation means  12 , depending on the logic value of the address A 0  contained the MRS or the EMRS. 
     The divider  14  includes a plurality of resistors R 1 , R 2 , R 3 , R 4  and R 5  connected in series between the output node of the switching means  13  and a ground node. One power supply voltage selected by the switching means  13  is divided into a plurality of voltages having various voltage levels according to resistor ratios among the resistors R 1 , R 2 , R 3 , R 4  and R 5 . 
     The decoder  15 , which is a control signal generation means, outputs control signals C 0 , C 1 , C 2  and C 3  for controlling turn-on/off of the switching section  16 . The decoder  15  receives signals A 1  and A 2  and outputs four control signals C 0 , C 1 , C 2  and C 3 . Herein, ‘A 1 ’ and ‘A 2 ’ are code signals stored in the MRS or the EMRS, and represent values of logic levels applied through corresponding pins A 1  and A 2 , respectively. For reference, although an embodiment of the present invention uses a 2-bit signal (A 1 , A 2 ) for controlling four switching elements N 1  to N 4  contained in the switching section  16 , a 3-bit signal (A 1 , A 2 , A 3 ) may be used to generate eight control signals C 0  to C 7  when the switching section  16  includes more switches. Herein, ‘A 3 ’ is a code signal stored in the MRS or the EMRS, and represents the value of a logic level applied through a corresponding pin A 3 . An enable signal ‘en’ is a signal for determining whether to enable the decoder  15  or not. When one of the voltages V 1  and V 2  is applied to the divider  14  by the switching means  13 , the decoder  15  reads the values of the signals A 1  and A 2  from the MRS or the EMRS to select and turn on one of the switching elements N 1  to N 4 . 
     The switching section  16  includes four NMOS transistors N 1 , N 2 , N 3  and N 4 , which are selectively turned on/off by the output signals C 0 , C 1 , C 2  and C 3  of the decoder  15 . That is, when all of the output signals C 0 , C 1 , C 2  and C 3  have a high level, all of the NMOS transistors N 1 , N 2 , N 3  and N 4  are turned on. As a result, a plurality of voltages, which are divided by the divider  14  so as to have various voltage levels, are selected to provide a high voltage Vpp, a core voltage Vcore, and reference voltages Vref 1  and Vref 2  to the memory device. The voltages Vpp, Vcore, Vref 1  and Vref 2  may be variously used for internal circuits of the memory device. For example, the high voltage Vpp may be used to activate word lines of the memory device, the core voltage Vcore may be used as a voltage required for the operation of a memory cell array, and the reference voltages Vref 1  and Vref 2  may be used as reference voltages for other internal voltage generators. 
       FIG. 2  is a circuit diagram illustrating a construction of the decoder  15  of the internal voltage supplier for the memory device shown in  FIG. 1 . 
     According to an embodiment of the present invention, the decoder  15  of the internal voltage supplier for the memory device includes a plurality of OR gates OR 1 , OR 2 , OR 3  and OR 4  and a plurality of NOR gates NOR 1 , NOR 2 , NOR 3  and NOR 4 . Each of the OR gates OR 1 , OR 2 , OR 3  and OR 4  exclusively receives a combination of one of the control signal A 1  and an inverted signal A 1   b  and one of control signal A 2  and an inverted signal A 2   b . Herein, the signal A 1   b  is a signal inverted from the control signal A 1  by an inverter IN 1 , and the signal A 2   b  is a signal inverted from the control signal A 2  by an inverter IN 2 . The NOR gates NOR 1 , NOR 2 , NOR 3  and NOR 4  receive the output signals of the OR gates OR 1 , OR 2 , OR 3  and OR 4 , respectively, and also receive an enable signal ‘en’ in common. 
     Hereinafter, the operation of the internal voltage supplier for the memory device according to an embodiment of the present invention will be described with the control signals A 1  and A 2  applied to the decoder  15 . 
     First, when both of the control signals A 1  and A 2  have a low level, the decoder  15  outputs only the control signal C 0  as a high level so as to transfer the control signal C 0  of a high level to the switching section  16 . As a result, only the NMOS transistor N 1  of the switching section  16  is turned on to provide a high voltage Vpp to the memory device. 
     Next, when only the control signals A 2  has a low level, the decoder  15  outputs only the control signal C 1  as a high level so as to transfer the control signal C 1  of a high level to the switching section  16 . As a result, only the NMOS transistor N 2  of the switching section  16  is turned on to provide a core voltage Vcore to the memory device. 
     In contrast, when the control signal A 2  has a high level and the control signal A 1  has a low level, only the control signal C 2  of the decoder  15  is outputted as a high level to turn on only the NMOS transistor N 3  of the switching section  16 . As a result, the first reference voltage Vref 1  is supplied to the interior of the memory device. 
     When both of the control signals A 1  and A 2  have a high level, only the control signal C 3  of the decoder  15  is outputted as a high level. As a result, only the NMOS transistor N 4  of the switching section  16  is turned on to supply the second reference voltage Vref 2  to the memory device. 
     As described above, according to the internal voltage supplier for the memory device of the present invention, the switching means  13  selects either the power supply voltage V 1  supplied from the interior of the memory device or the power supply voltage V 2  supplied from an exterior depending on the control signal A 0 , and transfers the selected power supply voltage to the divider  14 . When the switching means  13  selects the power supply voltage V 2  supplied from an exterior and transfers the selected power supply voltage V 2  to the divider  14 , the level of the power supply voltage V 2  changes to provide the high voltage Vpp, the core voltage Vcore, and the reference voltages Vref 1  and Vref 2  to the memory device. In other words, the internal voltage supplier for the memory device according to an embodiment of the present invention selects the power supply voltage V 2  supplied from the exterior of the memory device and transfers the selected power supply voltage V 2  to the memory device, when the power supply voltage V 1  supplied from the interior is unstable due to a problem in the fabricating process of the memory device, temperature or an operational malfunction. Generally, since the voltage V 2  has a larger current driving capability than the voltage V 1 , the voltage V 2  may be efficiently used for the stable operation of the memory device. 
     As described above, according to the internal voltage supplier for the memory device of the present invention, power supply voltages supplied from the interior and exterior of the memory device are selectively received to provide an internal voltage to the memory device. Therefore, when a power supply voltage supplied from an exterior is selected and provided, it is possible to stably provide an internal voltage to the memory device. Accordingly, the operation of the memory device becomes stable, thereby preventing a malfunction of the memory device. 
     Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.