Abstract:
A bit line sense amplifier circuit for use in a semiconductor memory device, and a control method thereof, in which the bit line sense amplifier circuit is controlled to maintain a precharge state thereof until a sense amplifier enable signal to enable the sense amplifier circuit is applied, thereby preventing the bit line sense amplifier circuit of the semiconductor memory device from floating, and preventing or substantially reducing a coupling effect, thereby providing a precise data sensing and amplification operation.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. § 119 from Korean Patent Application 10-2007-0069101, filed on Jul. 10, 2007, the contents of which are hereby incorporated by reference in their entirety for all purposes as if fully set forth herein. 
       BACKGROUND AND SUMMARY 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to semiconductor memory devices and, more particularly, to a bit line sense amplifier circuit for use in a semiconductor memory device and a control method thereof capable of preventing or substantially reducing the sense amplifier circuit from floating, and a coupling effect, with a precise data sensing. 
         [0004]    2. Discussion of Background and Summary 
         [0005]    Recent rapid development of the semiconductor industry has brought about a large capacity and high performance in semiconductor memory devices. This means a number of elements adapted in the semiconductor memory device provide a large capacity and high performance. In particular, the high performance of a sense amplifier used in the semiconductor memory device is becoming more important. 
         [0006]    More specifically, bit line sense amplifiers relating to data sense and amplification require items of relatively higher performance than earlier devices. 
         [0007]    The bit line sense amplifier circuit adapted for use in a semiconductor memory device is used for a general operation such as a data read or write operation to a memory cell, and senses and amplifies read or write data and outputs the read or write data to the external or memory cells. 
         [0008]    Qualities required in the sense amplifier circuit may be a high-level sensitivity, high-speed operation, wide operating range of power source voltage, low power consumption, small substrate area space and the like. Of these, the sense amplifier circuit needs a more precise data sensing operation based on a high sensitivity, because the semiconductor memory devices are achieving higher performance. 
         [0009]    The sense amplifier circuit for the semiconductor memory device has been researched with several solutions to obtain the precise data sensing operation based on high sensitivity. More specifically, when the semiconductor memory device is not under an active state of read or write operation, no power is applied to the sense amplifier circuit such that the sense amplifier circuit becomes in a floating state. Then, the sense amplifier circuit causes several problems, such as erroneous operation. According to the necessity to prevent the floating state in the sense amplifier circuit, a precharge circuit has been introduced. 
         [0010]    The precharge circuit is to supply a given level of voltage to the sense amplifier circuit, so that the sense amplifier circuit is not floated when the sense amplifier circuit is not in an active state, that is, when no power is applied thereto. The given level of voltage is called a precharge voltage, and the sense amplifier circuit is indicated as having a precharge state. 
         [0011]    A bit line sense amplifier adapted for use within the semiconductor memory device comprises at least one PMOS sense amplifier unit including plural PMOS transistors and at least one NMOS sense amplifier unit including plural NMOS transistors. The PMOS and NMOS sense amplifier units may have a cross-coupled sense amplifier type. Also, the sense amplifier circuit comprises a plurality of NMOS transistors receiving a given level of voltage for precharging. 
         [0012]    To execute the active operation, such as a read or write operation in the semiconductor memory device, a sense amplifier enable signal is provided to enable a plurality of sense amplifier units of the sense amplifier circuit. The sense amplifier units perform a sense and amplification operation in response to the sense amplifier enable signal. 
         [0013]    On the other hand, when the semiconductor memory device does not perform the active operation, the sense amplifier enable signal of the sense amplifier circuit is disabled. In this case, the precharge signal is enabled. A precharge voltage having a given level of voltage is supplied to the sense amplifier circuit in response to the precharge signal. 
         [0014]    As described above, a given level of precharge voltage is applied to the sense amplifier circuit not undergoing the active operation, thus, the sense amplifier circuit is prevented from being in a floating state. At this time, the state of the sense amplifier circuit is called a precharge state. 
         [0015]    The sense amplifier circuit is well known to those of ordinary skill in the art, thus, a further detailed description thereof is omitted herein. 
         [0016]      FIG. 1  illustrates timings for the operation of a conventional bit line sense amplifier circuit. 
         [0017]    As shown in  FIG. 1 , a time point when a bit line precharge signal BLP generated in a bit line precharge circuit within the bit line sense amplifier circuit is disabled is ‘t 1 ’. A time point when a sense amplifier precharge signal SAP is disabled in response to the bit line precharge signal BLP is ‘t 2 ’. A time point when a word line enable signal WL for an active state of the sense amplifier circuit  100  is enabled is ‘t 3 ’. A time point when a sense amplifier enable signal LAPG/LANG is enabled by the word line enable signal WL is ‘t 4 ’. 
         [0018]    The bit line precharge signal BLP of the bit line precharge circuit in the semiconductor memory device is disabled by an applied active command. The sense amplifier precharge signal SAP is disabled in response to the disabled bit line precharge signal BLP. Then, a word line is enabled in response to the word line enable signal WL. After the word line enable signal WL is enabled and a given time lapses, the sense amplifier enable signal LAPG/LANG is enabled. 
         [0019]    At this time, between the point of time when the word line enable signal WL is enabled and the point of time when the sense amplifier enable signal LAPG/LANG is enabled, a voltage appears between bit lines BL/BLB. That is, data of a memory cell is developed through the bit line. 
         [0020]    For a time interval between a time point ‘t 2 ’, when the precharge state is completed, and a time point ‘t 4 ’, when the sense amplifier enable signal LAPG/LANG is enabled, the sense amplifier circuit  100  is in the floating state. That is, even though the sense amplifier circuit  100  includes a sense amplifier precharge circuit, it is in the floating state between times ‘t 2 ’ and ‘t 4 ’. 
         [0021]    In the time interval of ‘t 2 ’ to ‘t 4 ’, a voltage is developed and a voltage level between the bit lines BL/BLB is changed. As the voltage development effect occurs between the bit lines BL/BLB, a coupling effect occurs between the drain and source of the PMOS and NMOS transistors within the plurality of sense amplifier units connected with the bit lines BL/BLB. This is why the sense amplifier circuit has a floating state during the time interval between ‘t 2 ’ and ‘t 4 ’. 
         [0022]    The coupling effect increases a potential of the plurality of sense amplifier units and, as a result, interrupts a precise sensing operation of the bit line sense amplifier circuit, causing a drop of sensing level. 
         [0023]    Accordingly, exemplary embodiments of the present invention provide a bit line sense amplifier circuit for use in a semiconductor memory device and a control method thereof. The bit line sense amplifier circuit can be prevented from having a floating state. A coupling effect of the bit line sense amplifier circuit can be prevented or substantially reduced, and a precise data sensing of the bit line sense amplifier circuit can be obtained. 
         [0024]    According to an exemplary embodiment of the present invention, a bit line sense amplifier circuit for use in a semiconductor memory device is characterized in that the bit line sense amplifier circuit is controlled to maintain a precharge state thereof until a point of time when a sense amplifier enable signal to enable the sense amplifier circuit is applied. 
         [0025]    A precharge completion time point of the sense amplifier circuit may occur later by a given time than a precharge completion time point of a bit line connected to the sense amplifier. A sense amplifier precharge signal to control a precharge of the sense amplifier circuit may be a signal generated in the sense amplifier circuit itself, in response to the sense amplifier enable signal. The sense amplifier precharge signal may be an inverted signal of the sense amplifier enable signal. The sense amplifier precharge signal of the sense amplifier circuit may be generated and applied in a specific signal generating circuit adapted to be outside the sense amplifier circuit. 
         [0026]    The sense amplifier circuit may comprise a sense amplifier for performing a sensing and amplification operation of data in response to the sense amplifier enable signal, and a sense amplifier controller for controlling a precharge state of the sense amplifier unit in response to a sense amplifier precharge signal. 
         [0027]    The sense amplifier may comprise at least one PMOS sense amplifier unit including a plurality of PMOS transistors cross-coupled with one another to amplify data; at least one NMOS sense amplifier unit including a plurality of NMOS transistors cross-coupled with one another to amplify data; and at least one PMOS transistor and at least one NMOS transistor for receiving respective sense amplifier enable signals to enable the sense amplifier units. 
         [0028]    The sense amplifier controller may comprise at least one inverter for receiving the sense amplifier enable signal and outputting a sense amplifier precharge signal having an opposed state to the sense amplifier enable signal; and a plurality of NMOS transistors that applies a precharge voltage level to the sense amplifier when the sense amplifier precharge signal is enabled, and that does not apply the precharge voltage level to the sense amplifier when the sense amplifier precharge signal is disabled. 
         [0029]    The precharge voltage level of the sense amplifier may be the same as a bit line precharge voltage level. The precharge voltage level may be ½ of the power voltage level. 
         [0030]    According to an exemplary embodiment of the present invention, a method of controlling a bit line sense amplifier circuit for use in a semiconductor memory device comprises a first step of enabling a sense amplifier precharge signal and maintaining a precharge state of the sense amplifier circuit; a second step of starting an active operation of the sense amplifier circuit, and applying a sense amplifier enable signal of the sense amplifier circuit to sense a bit line; and a third step of disabling the sense amplifier precharge signal in response to the sense amplifier enable signal. 
         [0031]    An applied time point of the sense amplifier precharge signal may be later by a given time than an applied time point of the bit line precharge signal. The sense amplifier precharge signal may be a signal generated in the sense amplifier circuit itself in response to the sense amplifier enable signal. The sense amplifier precharge signal may be an inverted signal of the sense amplifier enable signal. The sense amplifier precharge signal may be generated and applied in a specific signal generating circuit adapted to be outside the sense amplifier circuit. 
         [0032]    According to an exemplary embodiment of the present invention, a method of generating a sense amplifier precharge signal to precharge a bit line sense amplifier circuit comprises controlling an enable or disable state of the sense amplifier precharge signal, depending upon a sense amplifier enable signal controlling an operation of the sense amplifier circuit. 
         [0033]    The sense amplifier precharge signal may be an inverted signal of the sense amplifier enable signal. 
         [0034]    According to exemplary embodiments of the present invention as described above, a bit line sense amplifier circuit for use in a semiconductor memory device can prevent the sense amplifier circuit from becoming in a floating state, and a coupling effect can be prevented or substantially reduced, with precise data sensing and amplification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    Exemplary embodiments of the present invention will be understood in more detail from the following descriptions taken in conjunction with the accompanying drawings that are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
           [0036]      FIG. 1  illustrates timings for operation of a conventional bit line sense amplifier circuit; 
           [0037]      FIG. 2  is a block diagram of a bit line sense amplifier circuit according to an exemplary embodiment of the present invention; 
           [0038]      FIG. 3  illustrates in detail an exemplary embodiment of the sense amplifier circuit of  FIG. 2 ; 
           [0039]      FIG. 4  illustrates timings of operation per signal in the circuit of  FIG. 3 ; 
           [0040]      FIG. 5  is a block diagram of sense amplifier precharge signal generating circuit according to an exemplary embodiment of the present invention; and 
           [0041]      FIGS. 6A and 6B  are graphs illustrating a potential difference between sense amplifier units according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0042]    Exemplary embodiments of the present invention are more fully described below with reference to  FIGS. 2 to 6 . This invention may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein; rather, these exemplary embodiments are provided so that this disclosure is thorough and complete, and conveys the concept of the invention to those of ordinary skill in the art. 
         [0043]      FIG. 2  is a block diagram of a bit line sense amplifier circuit according to an exemplary embodiment of the present invention. 
         [0044]    Referring to  FIG. 2 , a bit line sense amplifier circuit  100  comprises a sense amplifier  110  and a sense amplifier controller  130 . 
         [0045]    The sense amplifier  110  receives a sense amplifier enable signal LAPG/LANG and operates to perform a sensing and amplification operation of data to be read from or written to a memory cell within the semiconductor memory device when the semiconductor memory device implements a read or write operation. The sense amplifier  110  may not operate in the write operation, but may operate only in the read operation. 
         [0046]    The sense amplifier controller  130  supplies a precharge voltage VBL with a given level to the sense amplifier  110  when the sense amplifier  110  has a precharge state. 
         [0047]    The sense amplifier circuit is described in more detail with reference to  FIG. 3 , as follows. 
         [0048]      FIG. 3  illustrates in detail an exemplary embodiment of the sense amplifier circuit of  FIG. 2 . 
         [0049]    As shown in  FIG. 3 , the bit line sense amplifier circuit  100  comprises the sense amplifier  110  and the sense amplifier controller  130 . 
         [0050]    The sense amplifier  110  comprises a plurality of PMOS sense amplifier units PSA 0  and PSA 1  and a plurality of NMOS sense amplifier units NSA 0  and NSA 1  connected between respective bit lines BL/BLB. 
         [0051]    The PMOS sense amplifier unit PSA 0  is constructed by connecting in series a plurality of PMOS transistors P 10  and P 20 , in which the first PMOS transistor P 10  is connected to a main bit line BL 0  and the second PMOS transistor P 20  is connected to a sub bit line BLB 0 . 
         [0052]    The NMOS sense amplifier unit NSA 0  is constructed by connecting in series a plurality of NMOS transistors N 10  and N 20 , in which the first NMOS transistor N 10  is connected to the main bit line BL 0  and the second NMOS transistor N 20  is connected to the sub bit line BLB 0 . 
         [0053]    The PMOS and NMOS sense amplifier units PSA 0  and NSA 0  adapted within the sense amplifier  110  have a cross-coupled connection. That is, the sense amplifier circuit may be a cross-coupled type. Unlike that, the sense amplifier circuit may be a sense amplifier circuit, such as a current mirror type or differential amplifier type and the like, well-known to those of ordinary skill in the art. 
         [0054]    As shown in  FIG. 3 , the sense amplifier controller  130  comprises a precharge circuit  132 , a precharge signal generating circuit  134 , and a power source circuit  136 . 
         [0055]    The precharge circuit  132  comprises a plurality of NMOS transistors N 110 , N 130  and N 150  receiving a precharge signal SAP through commonly connected gates. 
         [0056]    The first NMOS transistor N 130  is connected between the PMOS sense amplifier unit PSA 0  and a precharge voltage applying terminal, and supplies the precharge voltage VBL to the PMOS sense amplifier unit PSA 0 . 
         [0057]    The second NMOS transistor N 150  is connected between the precharge voltage applying terminal and the NMOS sense amplifier unit NSA 0 , and supplies the precharge voltage VBL to the NMOS sense amplifier unit NSA 0 . 
         [0058]    The third NMOS transistor N 110  is connected between the PMOS sense amplifier unit PSA 0  and the NMOS sense amplifier unit NSA 0 , and equalizes the potentials on the precharge voltage applying terminals of the two sense amplifier units PSA 0  and NSA 0 . 
         [0059]    The precharge signal generating circuit  134  comprises at least one inverter IVT. The precharge signal generating circuit  134  may have various constructions depending on the configuration of the precharge circuit  132 . For example, when the precharge circuit  132  is comprised of a plurality of PMOS transistors, the precharge signal generating circuit  134  may comprise at least one buffer. 
         [0060]    The power source circuit  136  comprises at least one PMOS transistor P 90  connecting the plurality of PMOS sense amplifier units PSA 0  and PSA 1  to a power terminal VDD, and at least one NMOS transistor N 90  connecting the plurality of NMOS sense amplifier units NSA 0  and NSA 1  to a ground power terminal VSS. 
         [0061]    Operation of the bit line sense amplifier circuit  100  is described as follows. 
         [0062]    In this exemplary embodiment, a data line (not shown) is coupled to the bit line BL 0  through a column selection signal. Then, a voltage corresponding to a voltage level of data of the bit line is applied to the data line. Assuming that in the bit lines BL 0 /BLB 0 , the main bit line BL 0  has a voltage of a low level and the sub bit line BLB 0  has a voltage of a high level; the second PMOS transistor P 20  of the PMOS sense amplifier unit PSA 0  is turned on by the low level voltage of the main bit line BL 0 , and the low level voltage is output through the PMOS sense amplifier unit PSA 0 . At this time, when the PMOS transistor P 90  connected to the power source terminal VDD receives a sense amplifier enable signal LAPG having a low level, the PMOS transistor P 90  is turned on, and the power source terminal VDD is coupled to the second PMOS transistor P 20 . Then, the low level voltage output through the second PMOS transistor P 20  is coupled with the power source terminal VDD, and is amplified to a level of the power source voltage. 
         [0063]    Because the sub bit line BLB 0  has a high level voltage, the first NMOS transistor N 10  is turned on, and outputs the high-level voltage. At this time, when the NMOS transistor N 90  coupled to the ground voltage terminal VSS receives a sense amplifier enable signal LANG having a high level, the NMOS transistor N 90  is turned on and the ground voltage terminal VSS is coupled to the first NMOS transistor N 10 . Thus, the high level voltage output through the first NMOS transistor N 10  is coupled to the ground power terminal VSS, and is dropped to a voltage of the ground voltage level. 
         [0064]    In bit lines BL 0 /BLB 0  and BL 1 /BLB 1  coupled with the column selection signal, the data sensing and amplification operation is performed similarly to the above description by the column selection signal, thus a further detailed description is omitted. 
         [0065]    As described above, in an active mode of performing a sensing and amplification operation of data, the sense amplifier  110  receives the sense amplifier enable signal LAPG/LANG from the outside, and performs the data sensing and amplification operation. Meanwhile, in a precharge mode not the active mode, the sense amplifier  110  does not receive the power source voltage level or the ground power level, but receives a precharge voltage level VBL supplied through the sense amplifier controller  130 . 
         [0066]    When the sense amplifier enable signal LANG is applied to the NMOS transistor N 90  that serves as a switching between the NMOS sense amplifier units NSA 0  and NSA 1  of the sense amplifier  110  and the ground voltage terminal VSS, the sense amplifier enable signal LANG is also applied to the precharge signal generating circuit  134 . The precharge signal generating circuit  134  inverts the sense amplifier enable signal LANG and outputs a sense amplifier precharge signal SAP in response to the applied sense amplifier enable signal LANG. In this exemplary embodiment, the sense amplifier precharge signal SAP may be a signal output through a plurality of buffers when the precharge circuit  132  includes plural PMOS transistors or receives the sense amplifier enable signal LAPG applied to the PMOS transistor P 90  to generate the sense amplifier precharge signal SAP. 
         [0067]    The sense amplifier precharge signal SAP generated through the precharge signal generating circuit  134  is applied to operate the precharge circuit  132 . 
         [0068]    The plurality of NMOS transistors N 110 , N 130 , and N 150  are turned on, to supply the precharge voltage VBL supplied to the plurality of NMOS transistors N 110 , N 130  and N 150  to the sense amplifier  110 , in response to the sense amplifier precharge signal SAP. For example, when the sense amplifier precharge signal SAP has a high level voltage, the third NMOS transistor N 110 , the first NMOS transistor N 130  and the second NMOS transistor N 150  are each turned on. The third NMOS transistor N 110  serves to equalize the potentials on the precharge voltage applying terminals of the plural PMOS sense amplifier units PSA 0  and the plural NMOS sense amplifier units NSA 0  of the sense amplifier  110  to the same voltage level. Also, the first NMOS transistor N 130  and the second NMOS transistor N 150  are each turned on in response to the sense amplifier precharge signal SAP. Thus, the precharge voltage level VBL supplied through the first NMOS transistor N 130  and the second NMOS transistor N 150  is supplied to first PMOS sense amplifier unit PSA 0  and first NMOS sense amplifier unit NSA 0  connected to selected-bit lines BL 0 /BLB 0 . As a result, the sense amplifier  110  does not become floating, even in a state that is not an active mode. In this exemplary embodiment, the precharge voltage level VBL may be ½ the voltage level of the power source voltage level. 
         [0069]    The state of respective signals of the bit line sense amplifier circuit is described as follows. 
         [0070]      FIG. 4  illustrates timings of operation per signal in the sense amplifier circuit  100  of  FIG. 3 . 
         [0071]    As shown in  FIG. 4 , a time when a bit line precharge signal BLP is disabled is t 1 . A time when a word line WL is enabled in response to a disabled bit line precharge signal BLP is t 2 . The sense amplifier enable signal LANG/LAPG is enabled in response to the enabled word line WL. A time simultaneous to that when the sense amplifier precharge signal SAP is disabled in response to the enabled sense amplifier enable signal LANG/LAPG is t 3 . 
         [0072]    As the bit line precharge signal BLP is disabled, from the time t 1  the bit line precharge circuit connected between the bit lines BL 0 /BLB 0  is disabled, and a precharge state of the bit lines BL 0 /BLB 0  is completed. That is, the precharge voltage level VBL is not supplied any more to the bit lines BL 0 /BLB 0 . Then, the active mode starts and the word line WL is enabled. After the word line WL is enabled, data of the memory cell is developed to the bit lines BL 0 /BLB 0 . Then, when the sense amplifier enable signal LANG/LAPG is enabled, the power source voltage level is supplied to the bit line sense amplifier circuit  100 , and so the sense amplifier  110  operates and performs a sensing and amplification operation. On the other hand, the sense amplifier precharge signal SAP is disabled in response to the sense amplifier enable signal LAPG/LANG in the sense amplifier controller  130 . Then the supply of the precharge voltage level VBL to the sense amplifier circuit is completed. 
         [0073]    At this time, as described above with reference to  FIG. 3 , the sense amplifier enable signal LANG/LAPG is received and inverted, thus the sense amplifier precharge signal SAP and the sense amplifier enable signal LANG applied to the NMOS transistor N 90  have mutually opposite logic states. 
         [0074]    When the sense amplifier enable signal LAPG applied to the PMOS transistor P 90  is received, however, the sense amplifier enable signal LAPG and the sense amplifier precharge signal SAP have the same state, as shown in  FIG. 4 . 
         [0075]    In a conventional case, as the sense amplifier precharge signal SAP is disabled in response to the bit line precharge signal BLP, the bit line sense amplifier circuit  100  has a floating state until the sense amplifier enable signal LANG/LAPG is enabled. 
         [0076]    According to exemplary embodiments of the present invention, the sense amplifier precharge signal SAP is disabled in response to the sense amplifier enable signal LANG/LAPG and does not respond to the bit line precharge signal BLP. Accordingly, in the bit line sense amplifier circuit  100 , the floating state that a supply of a voltage level is finished does not occur, even while changing the precharge mode to the active mode. 
         [0077]    Therefore, an error operation and the like of the bit line sense amplifier circuit  100  caused by the floating state of the bit line sense amplifier circuit  100  can be prevented, thereby increasing a sensitivity of the bit line sense amplifier circuit  100 . 
         [0078]    The sense amplifier precharge signal SAP increasing the sensitivity of the bit line sense amplifier circuit  100  may be generated in a sense amplifier precharge signal generating circuit (not shown) adapted specifically, instead of being generated within the bit line sense amplifier circuit  100  itself. 
         [0079]      FIG. 5  is a block diagram of a sense amplifier precharge signal generating circuit  135  according to an exemplary embodiment of the present invention. 
         [0080]    As shown in  FIG. 5 , the sense amplifier precharge signal generating circuit  135  comprises an NMOS sense amplifier unit controller  135   —   a , a PMOS sense amplifier unit controller  135   —   b , and a sense amplifier precharge controller  135   —   c.    
         [0081]    The NMOS sense amplifier unit controller  135   —   a  receives a block selection signal BLK_SEL and a first enable signal PNS from the external to enable the NMOS sense amplifier unit controller  135   —   a , and outputs the NMOS sense amplifier enable signal LANG in response to the received signals. 
         [0082]    The PMOS sense amplifier unit controller  135   —   b  receives the block selection signal BLK_SEL and a second enable signal PPS from the external to enable the PMOS sense amplifier unit controller  135   —   b , and outputs PMOS sense amplifier enable signal LAPG in response to the received signals. 
         [0083]    The sense amplifier precharge controller  135   —   c  outputs the sense amplifier precharge signal SAP in response to the block selection signal BLK_SEL. 
         [0084]    The NMOS sense amplifier unit controller  135   —   a , the PMOS sense amplifier unit controller  135   —   b , and the sense amplifier precharge controller  135   —   c  may be configured diversely by those of ordinary skill in the art, thus a detailed description therefor is omitted. 
         [0085]    A potential difference between the sense amplifier units according to an exemplary embodiment of the invention is described in detail, as follows. 
         [0086]    A general bit line sense amplifier includes a PMOS sense amplifier unit, an NMOS sense amplifier unit, and a precharging circuit. 
         [0087]      FIG. 6A  is a graph illustrating a potential difference between two nodes of the general bit line sense amplifier circuit when the general bit line sense amplifier is in a precharged state, and  FIG. 6B  is a graph illustrating a potential difference between a node P and a node N shown in  FIG. 3  according to an exemplary embodiment of the invention. 
         [0088]    In  FIGS. 6A and 6B , the ordinate axis represents a potential (V) and the abscissa axis represents time (nsec). 
         [0089]    In  FIG. 6A , a first trace G 1  indicates a change in the potential on a contact point where the PMOS sense amplifier unit and the precharging unit meet, and a second trace G 2  indicates a change in the potential on a contact point where the NMOS sense amplifier unit and the precharge unit meet in the conventional bit line sense amplifier circuit. In  FIG. 6B , a trace G 3  indicates a change in the potential on the node P shown in  FIG. 3  where the PMOS sense amplifier unit PSA 0  and the precharge circuit meet, and a trace G 4  indicates a change in the potential on the node N where the NMOS sense amplifier unit NSA 0  and the precharge circuit meet. 
         [0090]    At a time point TP in  FIGS. 6A and 6B , the potential difference of 104 mV is in the conventional case, but in an exemplary embodiment of the invention, the potential difference between the PMOS sense amplifier unit PSA 0  and the NMOS sense amplifier unit NSA 0  is generated as 8 mV. That is, as compared with the conventional sense amplifier circuit, in the exemplary embodiment of the present invention, the potential difference between the PMOS sense amplifier unit PSA 0  and the NMOS sense amplifier unit NSA 0  is hardly generated. Thus, a more precise data sensing of the bit line sense amplifier units can be obtained. 
         [0091]    Consequently, in the bit line sense amplifier  100 , the sense amplifier precharge signal SAP is disabled in response to the sense amplifier enable signal LANG/LAPG. That is, when the bit line sense amplifier circuit  100  is changed from a precharge mode to an active mode, the bit line sense amplifier circuit  100  can be prevented from floating. Moreover, the sense amplifier precharge signal SAP is generated by inverting the sense amplifier enable signal LANG/LAPG, thus it does not need to receive a sense amplifier precharge signal SAP specifically from the outside. 
         [0092]    In addition, a coupling effect caused according to a floating state of the bit line sense amplifier circuit  100  can be prevented, and thus the situation can be prevented in which a voltage level of the bit line sense amplifier circuit  100  is coupled-up or down according to a voltage level of the data loaded on the bit line BL 0 /BLB 0  and a sensing error occurs. 
         [0093]    As described above, according to exemplary embodiments of the present invention, a bit line sense amplifier circuit for use in a semiconductor memory device can prevent a sense amplifier circuit from floating and can prevent or substantially reduce a coupling effect, thereby obtaining a precise data sensing and amplification operation. 
         [0094]    It will be apparent to those of ordinary skill in the art that modifications and variations can be made in the present invention without deviating from the spirit or scope thereof. Thus, it is intended that the present invention cover any such modifications and variations and that these and other changes and modifications are seen to be within the true spirit and scope of the present invention as defined by the appended claims. 
         [0095]    In the drawings and specification, there have been disclosed exemplary embodiments of the present invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.