KR20080089023A - Semiconductor memory device with device to control word-line operation - Google Patents

Abstract

A semiconductor memory device with a word-line controller is provided to prevent unnecessary current consumption by preventing an operation error and to have rapid operation speed. A first pull-down driving unit(100) discharges a voltage on a node M1 to a node M2 in response to a plurality of address-information signals. A second pull-down driving unit(200) discharges a voltage on the node M2 to a ground voltage supplying stage in response to the plurality of address-information signals. A level retention unit(500) maintains the node M2 at a level corresponding to logic level 'H' when the second pull-down driving unit is turned off. A delay unit(400) outputs a feedback signal by inverting the voltage on the node M1, and outputs a word line-driving signal to control to drive a word line by delaying the feedback signal. A pull-up driving unit(300) performs pull-up driving of the node M1 in response to a word line-off signal and the feedback signal.

Description

Semiconductor memory device including word line driving control device {SEMICONDUCTOR MEMORY DEVICE WITH DEVICE TO CONTROL WORD-LINE OPERATION}

1 is an internal circuit diagram of a word line driving control apparatus in a semiconductor memory device according to the prior art.

FIG. 2A is a schematic view of the word line drive control device shown in FIG. 1; FIG.

FIG. 2B is a model of the word line drive control device shown in FIG. 2A in terms of parasitic resistance and capacitance; FIG.

FIG. 3 is a simulation waveform diagram of the prior art shown in FIG. 2A in the case where the level of high voltage is unstable.

4 is a simulation waveform diagram of transition of each node according to the magnitude of parasitic capacitance, unstable external voltage, and unstable high voltage.

Fig. 5A is a diagram showing a signal waveform in the case of pulling forward the deactivation time of a word line-off signal.

FIG. 5B is a simulation waveform diagram showing the level change of each node as the time of inactivation of the word line-off signal is advanced as in FIG. 5A. FIG.

6 is an internal circuit diagram of a word line driving control apparatus in a semiconductor memory device according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

500: Level Keeper

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor design technology, and more particularly, to a semiconductor memory device capable of reducing unnecessary power consumption by suppressing unnecessary driving according to data-input-output-pin-setting.

In general, semiconductor integrated circuits, in particular, semiconductor memory devices, use low voltage external voltages for internal driving and high voltages generated by boosting external voltages for driving specific portions. That is, it is common to use a voltage at a low output while calculating a signal with a low potential. As such, a low voltage can be used to reduce the amount of current consumed in the memory.

In particular, the DRAM includes a main word line driving control unit for controlling activation of a sub-word line through logic operation of an active signal. As such, the drive control unit generates a word line-drive signal by boosting a signal generated by a voltage equal to or similar to an external power supply voltage (at least generally designed to be smaller than a high voltage generated by boosting internally) to an internal high voltage. .

At this time, in the case of general DDR2, the high voltage stepped up to the external voltage 1.8V is 3.5V, the voltage level difference of about 2 times. Of course, there is a constant voltage difference between the external voltage and the high voltage, or research is being conducted toward lowering the level of the high voltage to cope with the low power design.

Meanwhile, the word line driving control apparatus provided in the semiconductor memory device will be described as follows.

1 is an internal circuit diagram of a word line driving control apparatus in a semiconductor memory device according to the prior art.

Referring to FIG. 1, the word line driving control apparatus according to the related art has a voltage applied to the node N1 in response to a plurality of address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0>. A pull-down driving unit 10 for pull-down driving, a pull-up driving unit 20 for pull-up driving the node N1 in response to a word line-off signal WLOFFB and a feedback signal FD, and a voltage applied to the node N1. Is inverted to output the feedback signal FD, and is delayed to output the word line-drive signal MWLB.

The pull-down driving unit 10 includes first to fourth drivers 11, 12, 13, and 14 for discharging the voltage applied to the node N1 to the node N2 in response to the address-information signal BAX34 <0: 3>. And fifth to discharge the voltage applied to the node N2 to the node N3 in response to the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0> BAX56 <0: 3>. The eighth driver 15, 16, 17, 18 and the node N3 in response to the address-information signals BAX34 <0: 3>, 56 <0: 3>, 78 <0>) BAX78 <0> And a ninth driver 19 for discharging the voltage.

For reference, when the word line driving signal MWLB is activated to the logic level 'L', the word line is activated to the high voltage level in response thereto. In addition, when the word line driving signal MWLB is deactivated to the logic level 'H', the word line is deactivated to the ground voltage level.

The high voltage VPP is a power source boosted by the external voltage VDD and has a voltage level higher than that of the external voltage VDD.

As such, the word line driving control apparatus is provided according to the address-information signal BAX78 <1: 3> applied to the ninth driver. Since only the address-information signal BAX78 <1: 3> to which they are applied are different and have the same driving, specific reference is omitted.

As mentioned above, to reduce power consumption, the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0> swing from the ground voltage to the external voltage level, and the word line- The off signal WLOFFB and the word line-drive signal MWLB swing from the ground voltage to the high voltage level.

Meanwhile, the driving will be briefly described.

First, when the address-information signals BAX78 <0>, BAX34 <0: 3>, and BAX56 <0: 3> are activated to a logic level 'H', the pull-down driving unit 10 is activated to discharge the node N1. The delay unit 30 inverts the voltage applied to the node N1 to activate the feedback signal FD to the logic level 'H' and the word line-drive signal MWLB to the logic level 'L'.

Further, the word line-off signal WLOFFB is activated at the logic level 'L', and the address-information signals BAX34,56 <0: 3>, 78 <0> are deactivated at the logic level 'L'. The pull-up driving unit 20 drives the node N1 to a high voltage level in response to the word line-off signal WLOFFB. Subsequently, the delay unit 30 inverts the node N1 to activate the feedback signal FD to the logic level 'L', and delay to deactivate the word line-drive signal MWLB to the logic level 'H'. In addition, the pull-up driving unit 20 drives the node N1 to have a high voltage VPP level in response to the word line-off signal WLOFFB and the feedback signal FD.

FIG. 2A is a view schematically illustrating the word line driving control apparatus shown in FIG. 1.

Referring to FIG. 2A, a conceptual diagram of a word line driving control apparatus includes a PMOS transistor PM1 having a word line-off signal WLOFFB as a gate input and a source-drain path between a supply terminal of a high voltage VPP and a node N1. NMOS transistor NM1 having an address-information signal BAX34 as a gate input and having a drain-source path between nodes N1 and N2, and a drain-source path between the nodes N2 and N3 with a gate-input of an address-information signal BAX56. NMOS transistor (NM2) having a gate input, an address-information signal BAX78 as a gate input, and a NMOS transistor (NM3) having a drain-source path between a node N3 and a supply terminal of a ground voltage, and a voltage across a node N1. PMOS transistor (PM3) having a source-drain path between the high voltage supply terminal and node FD, and the voltage applied to node N1 as a gate input, An NMOS transistor NM4 having a drain-source path between the supply terminals of the ground voltage, a PMOS transistor having a source-drain path between the supply terminal of the high voltage VPP and the node N1 as a gate input and having a voltage applied to the node FD. PM2) and an inverter I1 for inverting the voltage applied to the node FD and outputting the word line-drive signal MWLB.

In addition, the parasitic capacitance C3 is connected to the node N1, the parasitic capacitance C2 is connected to the node N2, and the parasitic capacitance C1 is connected to the node N3.

FIG. 2B is a model of the word line driving controller shown in FIG. 2A in terms of parasitic resistance and capacitance. In addition, the transistor was modeled as a switch.

As mentioned above, to reduce power consumption, the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0> are driven to the external voltage VDD, while the final word line The word line-driving signal MWLB for controlling the activation of the signal is driven to the high voltage VPP level. In addition, since the pull-down driving unit to which the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0> are applied is implemented in a small area, it has less parasitic resistance, but relatively parasitic capacitance. Will grow?

On the other hand, malfunction occurs due to parasitic capacitance that the word line driving control device itself has. In addition, when the level of the high voltage is unstable and the level difference between the external voltage and the high voltage is not constant, the above-described malfunction occurs more easily. This will be described with reference to the simulation waveform diagram.

FIG. 3 is a simulation waveform diagram of the prior art shown in FIG. 2A when the level of the high voltage is unstable.

As shown in Fig. 3, the address-information signal BAX78 is deactivated at logic level 'L', and the address-information signals BAX34 and BAX56 are activated at logic level 'H'.

Therefore, the PMOS transistor PM1 is not activated by the logic level 'H'. NMOS transistors NM1 and NM2 are active, and NMOS transistor NM3 is turned off.

Since the NMOS transistor NM3 is turned off, no pass is formed, but the charge stored in the capacitor C3 of the node N1 is partially introduced into the capacitors C1 and C2 by the turned-on NMOS transistors NM1 and NM2. Therefore, the voltage level of the node N1 falls.

Since the level of the node N1 falls and the PMOS transistor PM3 is turned on, the node FD rises to the logic level 'H' by this. The inverter I1 inverts the level of the node FD to activate the word line-drive signal MWLB to the logic level 'L'.

That is, even in a situation where all of the address-information signals BAX34, 56, and 78 do not satisfy the conditions for activation, a malfunction occurs in which the word line-drive signal MWLB is activated by the parasitic capacitances C1, C2, and C3. .

Moreover, as shown in Fig. 3, the level of the external voltage is stable at 2V, while the high voltage is not stable, as the level is between 2.1V and 3.5V.

As described above, when the level of the high voltage is unstable, the word line-off signal WLOFFB is activated to the logic level 'L', thereby reducing the amount of charge stored in the parasitic capacitance C3, so that the above malfunction occurs more easily. do.

The situation according to the transition of each signal is shown enlarged on the right side of the figure. As shown, it can be seen that the lower the level of the high voltage VPP, the lower the voltage level of the node N1 can be easily lowered to a level low enough to turn on the PMOS transistor PM1. Further, the lower the level of the high voltage VPP, the faster the level of the node FD transitions to the logic level 'H' to turn off the PMOS transistor PM2.

Therefore, the word line-driving signal MWLB, which should be maintained at the logic level 'H', has the address-information signals BAX34 <0: 3> and 56 <0: 3 under the above-mentioned conditions while the level of the high voltage is unstable. >, 78 <0>), it can be seen that the logic level 'L' is more easily activated.

On the other hand, Figure 4 is a simulation waveform diagram of the transition of each node according to the magnitude of the parasitic capacitance, the unstable external voltage level, and the unstable high voltage level.

4A illustrates a case where parasitic capacitance C3 has less capacitance than parasitic capacitances C2 and C1, where ΔC is a change amount of C. FIG. Where C = C1 + C2-C3. As shown, it can be seen that as DELTA C becomes larger, the level of the node N1 becomes unstable more quickly, resulting in a malfunction in which the word line-driving signal MWLB is activated under an incorrect condition. For reference, DELTA C at the time when malfunction starts to occur is 30 pF.

In addition, b is a diagram showing a case where the level of the high voltage VPP is stable at 2.8V, but the level of the external voltage VDD rises from 2.1V to 3.1V and is unstable. As the level of the external voltage VDD rises, the rate of transfer of charge from the node N1 to the node N2 is increased by the NMOS transistors NM1 and NM2, so that the level of the node N1 gradually decreases. Thus, as the level of the external voltage VDD rises, the word line-driving signal MWLB has a malfunction that is activated under an incorrect condition.

In addition, C is a diagram showing a case where the level of the external voltage VDD is stable at 2.1V, but the level of the high voltage VPP is unstable as the level of the high voltage VPP drops to a level between 3.1V and 2.1V. As the level of the high voltage VPP decreases, the level of the voltage applied to the node N1 also decreases. Therefore, when the NMOS transistors NM1 and NM2 are turned on and a charge share with the node N2 occurs, the level of the node N1 is easily lowered. Accordingly, it can be seen that as the level of the high voltage VPP is lowered, a malfunction occurs in which the word line-driving signal MWLB is easily activated under the wrong condition.

On the other hand, such a malfunction is maintained by maintaining the activation of the word line-off signal WLOFFB for a predetermined time until the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0> are activated. It can be prevented, but this has the disadvantage that unnecessary current consumption occurs. This will be described with reference to the following drawings.

FIG. 5A is a signal waveform diagram when the deactivation time of the word line-off signal WLOFFB is pulled forward from the activation time of the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0>. FIG. 5B is a simulation waveform diagram showing the level change of each node according to the earlier deactivation time of the word line-off signal WLOFFB.

Referring to FIG. 5B, a case in which the deactivation time of the word line-off signal WLOFFB is the same as the activation time of the address-information signals BAX34, 56, and 78 will be described first. The NMOS transistors NM1 and NM2 are turned on by the address-information signals BAX34 and 56, so that charges of the node N1 flow into the node N2. However, since the charge is supplied to the node N1 by the PMOS transistor PM1 turned on by the activation of the word line-off signal WLOFFB, the level of the node N1 decreases for a while and then recovers and maintains the logic level 'H'. do. Therefore, the node FD also instantaneously glitches when the node N1 falls, but the level is maintained at the logic level 'L', and the word line-driving signal MWLB is the same.

Therefore, when the deactivation time of the word line-off signal WLOFFB is the same as the application time of the address-information signals BAX34, 56, and 78, the malfunction of the word line-drive signal MWLB as described above does not occur. Do not.

On the other hand, as the deactivation time of the word line-off signal WLOFFB is earlier than the activation time of the address-information signals BAX34, 56, and 78, the charge share between the nodes N2 and N1 by the turned-on NMOS transistor is increased. Occurs. Accordingly, the level of the node N1 is lowered because, unlike the foregoing, the PMOS transistor PM1 is already turned off by deactivation of the word line-off signal WLOFFB, and thus cannot compensate for the insufficient charge by sharing. The occurrence of such malfunction occurs when the word line-off signal WLOFFB is deactivated at least 150 psec or more earlier than the address-information signal.

In particular, reference is made to the right part of the drawing, which is an enlarged view of the level transition time of each node. The direction of each arrow shows the level change of the node as the point of inactivation of the word line-off signal WLOFFB is pulled forward. As mentioned above, it can be seen that as the activation time of the word line-off signal WLOFFB becomes faster, the level of the node N1 decreases, so that the PMOS transistor PM3 turns on and the node FD rises to the logic level 'H'. Therefore, a malfunction occurs in which the word line-driving signal MWLB is activated to a logic level 'L' by the node FD.

Therefore, malfunctions caused by parasitic capacitances as described above can be prevented by adjusting the transition timing of the signals. However, the PMOS transistor and the NMOS transistor are simultaneously turned on by the word line-off signal WLOFFB and the address-information signals BAX34 <0: 3>, 56 <0: 3>, and 78 <0>. Unnecessary current consumption increases.

As described above, in the case of using the conventional technology, it can be seen that the word line-driving signal MWLB is incorrectly activated by parasitic capacitance. Furthermore, depending on the magnitude of the capacitance, the level variation of the external voltage or the high voltage and the voltage difference between the external voltage and the high voltage are highlighted. In order to prevent this, a method of adjusting the activation time of the signal is used, but there is a problem that excessive current consumption occurs because a path is formed from the supply terminal of the high voltage to the supply terminal of the ground voltage. In addition, the method of adjusting the activation time of the signal becomes slow at the activation time of the word line-driving signal, which is an obstacle to high speed operation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor memory device including a word line driving control device having a high driving speed and preventing unnecessary current consumption while preventing malfunction due to parasitic capacitance.

In accordance with an aspect of the present invention, a semiconductor memory device includes: first pull-down driving means for discharging a voltage applied to a node M1 to a node M2 in response to a plurality of address-information signals; Second pull-down driving means for discharging the voltage applied to the node M2 to the ground voltage supply terminal in response to the plurality of address-information signals; Level holding means for maintaining the node M2 at a level corresponding to a logic level 'H' when the second pull-down driving means is turned off; Delay means for inverting the voltage applied to the node M1 as a feedback signal and delaying the voltage to output a word line-drive signal for controlling the driving of the word line; And pull-up driving means for pull-up driving the node M1 in response to a word line-off signal and the feedback signal.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do.

6 is an internal circuit diagram of a word line driving control apparatus in a semiconductor memory device according to an embodiment of the present invention.

Referring to FIG. 6, the word line driving control apparatus of the present invention may include a first pull-down driving unit 100 for discharging the voltage applied to the node M1 to the node M2 in response to the address-information signal BAX34 <0: 3>. A second pull-down driving unit 200 for discharging the voltage applied to the node M2 to the ground voltage supply terminal in response to the address-information signals BAX56 <0: 3> and BAX78 <0>; When the pull-down driving unit 200 is turned off, the level holding unit 500 for maintaining the node M2 at a level corresponding to the logic level 'H' and the voltage applied to the node M1 are inverted and output as a feedback signal FD. A delay unit 400 for delaying and outputting the word line-drive signal MWLB, and a pull-up driving unit 300 for driving the node M1 in response to the word line-off signal WLOFFB and the feedback signal FD. ).

In addition, the second pull-down driving unit 200 is connected in parallel between the node M2 and the node M3, the NMOS transistors NM9, NM10, NM11, NM12 driven in response to the corresponding address-information signal BAX56 <0: 3>, And a NMOS transistor NM13 for discharging the voltage applied to the node M3 to the supply terminal of the ground voltage in response to the address-information signal BAX78 <0>.

The first pull-down driving unit 100 includes NMOS transistors NM5, NM6, NM7, and NM8 connected in parallel between the node M1 and the node M2 and driven in response to the corresponding address-information signal BAX34 <0: 3>. .

The delay unit 400 inverts the voltage applied to the node M1 to output the feedback signal FD, and inverts the output signal of the inverter I2 to output the word line-drive signal MWLB. For the inverter I3.

The pull-up driving unit 300 includes a word line-off signal WLOFFB as a gate input and a PMOS transistor PM4 having a source-drain path between the supply terminal of the high voltage VPP and the node M1 and a feedback signal FD. It includes a PMOS transistor (PM5) having the applied voltage as a gate input and having a source-drain path between the supply terminal of the high voltage (VPP) and the node M1.

The level maintaining unit 500 includes a PMOS transistor PM6 for applying the high voltage VPP to the node M2 in response to the address-information signal BAX78 <0>.

For reference, even when the external voltage VDD is applied as the driving power of the level maintaining part 500, the same effect can be obtained. The same effect can also be obtained by using an NMOS transistor instead of a PMOS transistor.

In addition, the present invention is provided according to the address-information signal BAX78 <1: 3> applied to the NMOS transistor NM13. Since only the address-information signal BAX78 <1: 3> to which they are applied are different and have the same circuit implementation and driving, specific reference is omitted.

Meanwhile, the driving will be briefly described. In particular, the case where the address-information signals BAX34 <0: 3> and BAX56 <0: 3> have a logic level H, and the address-information signal BAX78 <0> have a logic level 'L' will be described. Under these conditions, there has conventionally been a malfunction in which the word line-driving signal MWLB is activated to a logic level 'L' in accordance with the parasitic capacitance and the level variation of the external voltage VDD and the high voltage VPP.

First, since the NMOS transistors NM5 to NM12 in the first and second pull-down driving units 100 and 200 are active, charge sharing is performed between the nodes M1 and M2. In addition, since the address-information signal BAX78 <0> is deactivated to the logic level L, the PMOS transistor PM6 of the level holding unit is activated to drive the node M2 at a high voltage. Thus, even if charge sharing between nodes M1 and M2 occurs, the level of node M1 is not low enough to turn on the PMOS transistor in inverter I2. For reference, the NMOS transistor NM13 is off at this time.

Subsequently, the delay unit 30 inverts the voltage applied to the node M1 to deactivate the feedback signal FD to the logic level 'L' and the word line-drive signal MWLB to the logic level 'H'.

On the other hand, the semiconductor memory device according to the present invention described above further adds a level holding part even if the address-information signals BAX34 and BAX56 transition to the logic level 'H' while the address-information signal BAX78 maintains the logic level 'L'. By including the node M2 to maintain the logic level 'H', the voltage level of the node M1 does not drop.

Further, even if the time of deactivation of the word line-off signal is earlier than the time of activation of the address-information signal, the level of the node M2 is maintained at the high voltage level by the level maintaining portion, so that the level of the node M1 does not fall, so that the conventional parasitic capacitor Malfunctions caused by charge sharing occurring in between are prevented. Therefore, the time for deactivation of the word line-off signal can be made faster, so that faster driving can be achieved.

The above effects are the same even when the levels of the external voltage and the high voltage are unstable.

Therefore, as described above, the word line drive control apparatus having a step of boosting a signal from an external voltage to a high voltage level prevents malfunction due to parasitic capacitance, external voltage, and high voltage level of each node. Therefore, it is possible to have a margin in the deactivation of the signal and the determination of the activation time, thereby enabling faster driving.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

The above-described present invention can prevent malfunction due to parasitic capacitance, external voltage and high voltage level of each node, and can be driven faster by deactivation of signal and margin at the time of activation.

Claims (10)

First pull-down driving means for discharging the voltage applied to the node M1 to the node M2 in response to the plurality of address-information signals; Second pull-down driving means for discharging the voltage applied to the node M2 to the ground voltage supply terminal in response to the plurality of address-information signals; Level holding means for maintaining the node M2 at a level corresponding to a logic level 'H' when the second pull-down driving means is turned off; Delay means for inverting the voltage applied to the node M1 as a feedback signal and delaying the voltage to output a word line-drive signal for controlling the driving of the word line; And Pull-up driving means for driving the node M1 in response to a word line-off signal and the feedback signal; A semiconductor memory device having a. The method of claim 1, The second pull-down driving unit, First to fourth drivers connected in parallel between the node M2 and the node M3 and driven in response to first to fourth address-information signals; And a fifth driver for discharging the voltage applied to the node M3 to the supply terminal of the ground voltage in response to a fifth address-information signal. A semiconductor memory device characterized in that. The method of claim 2, The level maintaining means, And a first PMOS transistor for applying the high voltage to the node M2 in response to deactivation of the fifth address-information signal. A semiconductor memory device characterized in that. The method of claim 2, The level maintaining means, And a first PMOS transistor for applying the external voltage to the node M2 in response to the deactivation of the fifth address-information signal. A semiconductor memory device characterized in that. The method of claim 2, The level maintaining means, And a first NMOS transistor for applying the high voltage to the node M2 in response to deactivation of the fifth address-information signal. A semiconductor memory device characterized in that. The method of claim 2, The level maintaining means, And a first NMOS transistor for applying the external voltage to the node M2 in response to deactivation of the fifth address-information signal. A semiconductor memory device characterized in that. The method according to any one of claims 2 to 6, The first pull-down driving means, And a sixth to ninth driver connected in parallel between the node M1 and the node M2 and driven in response to the sixth to ninth address-information signals. A semiconductor memory device characterized in that. The method of claim 7, wherein The delay means, A first inverter for inverting the voltage applied to the node M1 and outputting the feedback signal, and a second inverter for inverting the output signal of the first inverter and outputting the word line driving signal; A semiconductor memory device characterized in that. The method of claim 8, The pull-up driving means, A second PMOS transistor having the word line-off signal as a gate input and having a source-drain path between the high voltage supply terminal and the node M1; A third PMOS transistor having a voltage applied to the feedback signal as a gate input and having a source-drain path between the high voltage supply terminal and the node M1; A semiconductor memory device characterized in that. The method of claim 9, And the first to ninth drivers are NMOS transistors.

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