US005602796A
`5,602,796
`[11] Patent Number:
`(15)
`United States Patent
`Sugio
`[45] Date of Patent:
`Feb. 11, 1997
`
`
`ATTRA ECTYAAU
`
`[75]
`
`[54] WORD LINE DRIVER IN A
`SEMICONDUCTOR MEMORYDEVICE
`Inventor: Kenichiro Sugio, Miyazaki, Japan
`.
`.
`.
`[73] Assignee: Oki Electric Industry Co., Ltd.,
`Tokyo, Japan
`
`[21] Appl. No.: 318,175
`[22]
`Filed:
`Oct. 5, 1994
`
`Foreign Application Priority Data
`[30]
`Oct. 13, 1993
`[JP]
`Japan eeeeeeccessesereeeesceee 5-255424
`[SD]
`Lint, C19 onecceeeeecssssssssssssnseecsenceensnsssssssecesees G11C 8/00
`[52] U.S. Cl.
`365/230.06: 365/230.08
`
`58] Field of Search
`3651230 06, 230 08
`"365/189.09 189 11: 326.180. 86
`~ 7“
`,
`.
`Cited
`f
`Cite
`References
`U.S. PATENT DOCUMENTS
`
`.
`oO oyieod amt ‘
`” aeepaone
` 5,394,374
`2/1995 Ishimura
`365/230.06
`
`56
`6]
`
`FOREIGN PATENT DOCUMENTS
`
`.
`
`0551598
`63-113888
`
`7/1993 European Pat. Off.
`5/1988
`Japan .
`OTHER PUBLICATIONS
`“Cross—Coupled Level-Shifting Low-Voltage Wordline
`Driver For Dram,” IBM Technical Disclosure Bulletin, vol.
`34, No. 4B, Sep. 1991, Armonk, NY, pp. 332-334.
`
`Primary Examiner—P. Zarabian
`Attorney, Agent, or Firm—Law Office of Steven M. Rabin,
`PC.
`
`ABSTRACT
`[57]
`A word line driver has a decoder for outputting decode
`_signals havingfirst and secondlogic levels, levelshifters for
`teceiving the respective decode signals, each level shifter
`outputting drive signal having first and third logic levels in
`responseto the received decode signal, the third logic level
`being higher than the second logic level; a pumping circuit
`for outputting wordline activation signals, at least one of the
`paming
`gna's,
`wordline activation signals having the third logic level; and
`groups of output circuits, each group having the output
`circuits connected to one of the level shifters and a word
`line, respectively, each of the output circuits outputting the
`word line activation signal to the respective word line in
`response to the decode signal and the drive signal.
`
`0405812
`
`1/1991
`
`European Pat. Off.
`
`.
`
`13 Claims, 4 Drawing Sheets
`
`
`
`
`
`
`
`
`
`
`
`
`
`APPLE 1012
`
` —WL-I-m
`
`
`PWI---PWm
`Vv
`
`
`
`7—WL-l-1
`
`WL-L-I
`
`WL-L-m
`
`APPLE 1012
`
`1
`
`

`

`U.S. Patent
`
`Feb. 11, 1997
`
`Sheet 1 of 4
`
`5,602,796
`
`FIG. |
`
`-I-|
`
`|
`
`|
`
`{
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`N4I-I
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`0
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`——
`|
`— WL-I-m
`po
`
`N4S-|
`
`r
`
`2
`
`

`

`U.S. Patent
`
`Feb. 11, 1997
`
`Sheet 2 of 4
`
`5,602,796
`
`
`
`LINDHIOAWWYeVT1WS9AMOWSAN2HAAG
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`Mantme
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`

`

`U.S. Patent
`
`Feb. 11, 1997
`
`Sheet 3 of 4
`
`5,602,796
`
`FIG.3
`
`WL |
`
`PWm
`
`N4I
`
`N43
`
`N45
`
`PW |
`
`WLm
`
`4
`
`

`

`U.S. Patent
`
`Feb. 11, 1997
`
`Sheet 4 of 4
`
`5,602,796
`
`PWI---PWm
`
`N45-1_
`0
`|
`Pot =4
`VP
`;
`|
`|) |
`
`ANG
`
`|
`
`50-I-1
`53-I-1
`
`:
`i]—~L5I-I-|
`!
`~~1524-|
`
`
`
`WL-I-I
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`WL-I-m
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`WL-L-|
`
`WL-L-m
`
`
`
`5
`
`

`

`5,602,796
`
`2
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`FIG. 1 is a circuit diagram ofa part of a word line driver
`6 showing one embodiment of the present invention. The
`word line driver 6 is employed in a DRAM,for example. A
`block diagram of the DRAM to which the word line driver
`6 is applied, is shown in FIG.2.
`The DRAM to which the present invention is applied, will
`first be described with reference to FIG. 2.
`
`10
`
`1
`WORD LINE DRIVER IN A
`SEMICONDUCTOR MEMORYDEVICE
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application claims rights of priority under 35 USC
`§119 of Japanese Patent Application Serial No. 255424/
`1993, filed Oct. 13, 1993, the entire disclosure of whichis
`incorporated herein by reference.
`
`BACKGROUNDOF THE INVENTION
`
`This invention relates to a semiconductor integrated cir-
`cuit device such as a Dynamic Random Access Memory
`(hereinafter called “DRAM”), a Static Random Access
`Memory (hereinafter called “SRAM”),
`a Read Only
`Memory(hereinafter called ‘“ROM”) or the like, and par-
`ticularly to a word line driver employed in the semiconduc-
`tor integrated circuit device.
`A semiconductor memory device such as a DRAM has a
`word line driver for selecting one of plural memory cells.
`This type of word line driver has been disclosed in, for
`example, Japanese Patent Application Laid-Open Publica-
`tion No. 63-113888, laid-open to public inspection on May
`18, 1988.
`
`SUMMARYOF THE INVENTION
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`While the specification concludes with claims particularly
`pointing out and distinctly claiming the subject matter which
`is regarded as the invention, and it is belicvcd that the
`invention, the objects, features and advantages thereof, will
`be better understood from the following description taken in
`connection with the accompanying drawings in which:
`FIG. 1 is a circuit diagram of a part of a word line driver
`showing an embodiment of the present invention;
`FIG. 2 is a view illustrating a DRAM to which the word
`line driver shown in FIG. 1, according to the present
`invention, is applied;
`FIG.3 is a timing chart for describing the operation of the
`word line driver shown in FIG, 1; and
`FIG. 4 is a circuit diagram of the entire word line driver
`shown in FIG. 1.
`
`The DRAM comprises a timing control circuit 1 for
`receiving a control signal CT and a clock CK therein and
`outputting therefrom control signals $, for controlling tim-
`ings provided for respective components, a row address
`decoder 2 for decoding a row address ADR, so as to output
`therefrom a group of decode signals A having a plurality of
`decode signals A-1 through A-1, a column address decoder
`3 for decoding a column address ARC so as to output a
`decodesignal for selecting any of bit lines BL, through BL,,
`and @ pumping circuit 4 for pumping or boosting a power
`source voltage VCC (first power source voltage) so as to
`generate a pumped voltage VP (-VCC+V,ta, where V;:
`threshold voltage and a: positive voltage value).
`The word line driver 6 is electrically connected to the
`pumping circuit 4 through a pumping driver 5. A pumping
`means comprises the pumping circuit 4 and the pumping
`driver 5. The pumping driver 5 serves as a circuit for
`outputting word line activation signals PW, through PW,,, to
`the word line driver 6 based on a row address ADR,.
`The word line driver 6 serves as a circuit for selectively
`It is an object of the present invention to provide a word
`driving word lines WL,_, through WL,.,, based on the group
`line driver capable of reducing the number of elements as
`of decode signals A and word line activation signals PW,
`compared with a word line driver employed in a conven-
`through PW,,. A memory cell array 7 is electrically con-
`tional semiconductor memory device and providingareli-
`nected to the word line driver 6. The memory cell array 7 is
`able operation.
`constructed in such a mannerthat a plurality of memory cells
`In orderto achieve the above object, the present invention
`7a are respectively electrically connected to points where
`provides a word line driver comprising a decoder for out-
`the plurality of word lines WL,., through WL,,,, and the
`putting decode signals having first and secondlogic levels,
`plurality of bit lines BL, through BL,, intersect respectively
`level shifters for receiving the respective decode signals,
`and the memory cells 7a are arranged in matrix form.A bit
`each level shifter outputting a drive signal having first and
`line driver 8 is electrically connected to the bit lines BL,
`third logic levels in response to the received decodesignal,
`through BL,,. The bit line driver 8 serves as a circuit for
`selectively driving the bit lines BL, through BL, based on
`the third logic level being higher than the secondlogic level;
`the decode signal output from the column address decoder3.
`a pumping circuit for outputting word line activation signals,
`at least one of the word line activation signals having the
`Further, an input buffer 9 is provided in the DRAM. The
`third logic level; and groups of outputcircuits, each group
`inputbuffer 9 servesas a circuit for receiving input data D;
`having the output circuits connected to one of the level
`therein and outputting the same to a read/write (hereinafter
`shifters and a word line, respectively, each of the output
`abbreviated as “R/W”) controller 10. The R/W controller 10
`circuits outputting the word line activation signal
`to the
`serves as a circuit for determining, based on the control
`respective wordline in response to the decodesignal and the
`signal S,, whether data is written into or read from a
`drive signal.
`corresponding memory cell 7a. An output buffer 12 is
`electrically connected to the R/W controller 10 through a
`sense amplifier 11. The sense amplifier 11 serves as a circuit
`for amplifying the output of each memory cell 7a. The
`output buffer 12 servesas a circuit for recciving the output
`of the sense amplifier 11 and outputting output data D,
`therefrom.
`
`15
`
`20
`
`25
`
`30
`
`350
`
`35
`
`The word line driver 6 provided in the DRAM shownin
`FIG. 2 will now be described with reference to FIG. 1. The
`word line driver 6, a part of which is shown in FIG.1, is
`comprised of complementary MOS (Complementary Metal
`Oxide Semiconductor hereinafter called “(CMOS”) transis-
`tors and basically has a plurality of level shifters 40-1
`through 40-1 (FIG. 1 showsonly one level shifter 40-1) and
`a plurality of groups of output units 50-1-1 through 50-I-m
`(FIG. 1 shows only one group of output units 50-1-1 through
`50-1-m).
`The level shifter 40-1 has an inverter 41-1 for inverting
`the decode signal A-1 and an N-channel MOStransister
`
`60
`
`65
`
`6
`
`

`

`5,602,796
`
`3
`(hereinafter called “NMOS”) 42-1 serving as a pull-down
`switching mcans whose gate is controlled based on the
`decode signal A-1. The gate of an NMOS43-1 is electrically
`connected to a node N41-1 on the output side of the inverter
`41-1 and the source thereof is electrically connected to the
`ground. Further, the drain of the NMOStransistor 43-1 is
`electrically connected to a latch circuit for latching a
`pumped voltage VP therein. The latch circuit comprises
`P-channel MOStransistors (hereinafter called “PMOS”)
`transistors 44-1 and 45-1. The drain and gate of the PMOS
`44-1 and the drain and gate of the PMOS45-1 are electri-
`cally cross-connected between a node N43-1 and the node
`N45-1. Further, the sources of the PMOSs 44-1 and 45-1 are
`connected to the boosted voltage VP.
`The output unit 50-1-1 comprises a PMOS(first transis-
`tor) 51-1-1 and NMOSs(secondandthird transistors) 52-1-1
`and 53-1-1. The source(first electrode), drain (second elec-
`trode) and gate of the PMOS 51-1-1 are respectively elec-
`trically connected to the word lineactivation signal PW,, the
`word line WL,_, and the node N45-1 on the output side of
`the level shifter 40-1. The NMOS 52-1-1 whose gate is
`controlled based on a potential at
`the node N45-1,
`is
`electrically connected between the drain of the PMOS
`51-1-1 and the ground. The drain of the NMOS 53-1-1
`whose gate is controlled based on the decodesignal A-1, is
`electrically connected to the word line activation signal
`PW,. Further, the source of the NMOS53-1-1 is electrically
`connected to the word line WL, ,.
`Other output units 50-1-2 through 50-1-mrespectively
`comnected to the node N45-1 respectively have a circuit
`configuration identical
`to that of the output unit 50-1-1.
`Namely,the output unit 50-1-m comprises a PMOS 51-1-m,
`an NMOS 52-1-m and an NMOS53-1-m. The source, drain
`and gate of the PMOS 51-1-m are respectively electrically
`connected to the word line activation signal PW,,,, the word
`line WL,.,,, and the node N45-1 on the output side of the
`level shifter 40-1. The NMOS 52-1-m, whose gate is con-
`trolled based on the potential at the node N45-1, is electri-
`cally connected between the drain of the PMOS 51-1-m and
`the ground. The drain of the NMOS 53-1-m, whose gate is
`controlled based on the decode signal A-1, is clectrically
`connected to the word line activation signal PW,,,. Further,
`the source of the NMOS 53-1-m whose gate is controlled
`based onthe first decode signal A-1, is electrically connected
`to the word line WL,.,,.
`The operation of the word line driver 6 will now be
`described below.
`
`FIG.3 is a timing chart for describing the operationof the
`word line driver 6 shown in FIG.1. In FIG.3, the abscissa
`indicates the time and the ordinate indicates the voltage.
`Write and read operations (1) and (2) shown in FIGS. 1 and
`2, which are executed where the output circuit 50-1 is
`activated and the word line WL,_,
`is selected, will be
`described belowwith reference to FIG. 3 as an illustrative
`example.
`(1) Write operation
`the
`When the power source voltage VCC is applied,
`timing control circuit 1 outputs the control signals 5, for
`controlling the timings provided for the respective compo-
`nents, based on the control signal CT and the clock CK.
`Further, the pumping driver 5 outputs the word line activa-
`tion signals PW, through PW,, to the word line driver 6
`based on the row address ADR, (each of the word line
`activation signals is of a signal having a ground level or a VP
`level and any of the signals PW, through PW,, is selectively
`brought to the VP level). On the other hand, the row address
`
`15
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`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`55
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`60
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`65
`
`4
`decoder 2 decodes the row address ADR, so as to output the
`group of decode signals A therefrom. Further, the column
`address decoder 3 decodes the column address ARC soas to
`output the decode signal for selecting any of the bit lines
`BL,through BL,,. On the other hand, the R/W controller 10
`is brought into a data write operating state based on the
`control signal S, input from the timing control circuit 1.
`(a) Set operation
`Whenthe level of the decode signal A-1 which is one of
`the group of decode signals A changes from the groundlevel
`to the VCC, the NMOSs 42-1 and 53-1-1 through 53-1-m are
`turned on so that the potential at the node N45-1 is brought
`to the ground level. As a result, the PMOSs 51-1-1 through
`§1-1-m are broughtinto an onstate. On the other hand, when
`the level of the word line activation signal PW, changes
`from the ground level
`to the VP level,
`the VP level
`is
`supplied to the word line WL, , through the NMOS 53-1-1
`which has been already turned on but is not fully supplied
`thereto due to the threshold of the NMOS 53-1-1. However,
`the wordline activation signal having the VP levelis sent to
`the word line WL,.,
`through the PMOS 51-1-1. Thus, a
`plurality of memory cells electrically connected Lo the word
`line WL,_, are turned on. Further, one of the bit lines BL,
`through BL, is selected by the bit line driver 8 so that one
`memory cell 7a is selected.
`(b) Reset operation
`When the level of the word line activation signal PW,
`changes from the VP levelto the groundlevel, the word line
`activation signal having the groundlevel is sent to the word
`line WL,_, through the NMOS53-1-1 and the PMOS 51-1-1
`which have already been turned on.
`When the level of the decode signal A-1 then changes
`from the VCClevel to the ground level, the NMOS42-1 and
`the NMOS53-1-1 are brought into an off state. Further, the
`inverter 41-1 changes the level of the node N41-1 from the
`ground level to the VCC level. Thus, the NMOS 43-1 is
`turned on,so that the level of the node N43-1 is broughtto
`the groundlevel so as to turn on the PMOS45-1. Asa result,
`the level ofthe node N45-1 changes from ground levelto the
`VP level. Thus, the PMOS 51-1-1 is turned off and the
`NMOS52-1-1 is turned on in response to the VP level of the
`node N45-1 so that the resetting of the word line WL,_, is
`completed.
`(2) Read operation
`The R/W controller 10 is brought into a data read oper-
`ating state based on the control signal S,. Set and reset
`operations for selecting a desired word line are performed in
`a manner similar to the write operation. The output data D,
`can be read out from the output buffer 12 based on an
`address selected by the bit line driver 8.
`The word line driver of the present embodiment shows
`only one level shifter 40-1 which is selected based on the
`decode signal A-1. However, the word line driver includes
`level shifters 40-1 to 40-1 and output circuits 50-1-1 to
`50-1-m as shown in FIG.4.
`
`In FIG.4, the word line activation signal PW, is inputto
`output circuits 50-1-1 to 50-1-1. In the same manner, the
`word line activation signals PW. (not shown in FIG.4) to
`PW,,, are input to output circuits 50-1-2 to 50-1-2 (not shown
`in FIG. 4) to 50-1-m to 50-1-m. In the present embodiment,
`only oneof the wordline activation signals PW, to PW,has
`the VP level, while the other word line activation signals
`have the ground level.
`The word line driver shown in FIG. 4 has level shifters
`40-1 to 40-1 each of which receives one ofthe decode signals
`
`7
`
`

`

`5,602,796
`
`5
`A-1 to A-l, respectively. The level shifters 40-1 to 40-1 are
`coupled to the output circuits 50-1-1 to 50-1-1, 50-1-2 to
`50-1-2, .. .
`, 50-1-m to 50-1-m, respectively. In the present
`embodiment, only one of the decode signals A-1 to A-] has
`the VCC level which is lower than the VP level, while the
`other decode signals have the ground level.
`the word line
`Now,
`the case will be explained that
`activation signal PW, having the VP level is input to the
`output circuits 50-1-1 to 50-1-1 and the decode signal A-1
`having the VCClevel is input to the level shifter 40-1, i.e.,
`the word line WL,_, is selected. At this time, a voltage level
`of the gate of the NMOS 53-1-1 ofthe selected output circuit
`50-1-1L is the VCC level and a voltage levet ofthe gate of the
`PMOS51-1-1 of the selected output circuit 50-1-1 is the
`groundlevelsince the selected level shifter 40-1 outputs the
`ground level signal to the node N45-1. Then, both of the
`NMOS53-1-1 and PMOS 51-1-1 are in an on state. There-
`fore, the word line activation signal PW, having the VP level
`is supplied to the word line WL,.,
`through the NMOS
`53-1-1 and PMOS 51-1-1.
`
`At the sametime, for example, a voltage level ofthe gate
`of the NMOS 53-1-1 of the non-selected output circuit
`50-1-1 is the ground level and a voltage level of the gate of
`the PMOS51-1-1 of the non-selected outputcircuit 50-1-1 is
`the VP level, since the decodesignal A-| has the ground level
`and the non-selected level shifter 40-1 outputs the VP level
`signal to the node N45-]. Then, both of the NMOS 53-1-1
`and PMOS51-1-1 are in the off state. Therefore, the word
`line activation signal PW, having the VP level
`is not
`supplied to the word line WL,., through the NMOS 53-1-1
`1-1 and PMOS 51-1-1.
`If the word line driver does not have the level shifter 40-1
`as the prior word line driver does, the PMOS 51-1-1 of the
`non-selected output circuit 50-1-1 receives the VCC level
`since the inverted decode signal A-1 has the VCC level.
`Then, the PMOS 51-1-1 is not completely in the off state
`since the VP level signal is applied to the source of the
`PMOS51-1-1. Therefore, a part of the voltage level of the
`word line activation signal PW, leaks outto the non-selected
`word line WL,., through the PMOS 51-1-1.
`According to the present invention, as has been described
`the above, the NMOSs 53-1-1 through 53-]-m for receiving
`the decode signals A-1 through A-] as the gate input corre-
`sponding to the input of each level shifter, and the PMOSs
`§1-1-1 through 51-l-m whoseeach gate is controlled based
`on the voltage having the VP level, which correspondsto the
`outputof the level shifter, are used as means for transmitting
`the word line activation signals to their corresponding word
`lines. Therefore,
`the word line activation signal can be
`teliably sent to a desired wordline alone. Thus, the read and
`write operations can be stably performed. Further, since one
`level shifter serves so as to drive a plurality of output
`circuits, the number of elements can be reduced.
`While the present invention has been described with
`reference to the illustrative embodiment, this description is
`not intended to be construed in a limiting sense. Various
`modifications of the illustrative embodiment will be appar-
`ent to those skilled in the art on reference to this description.
`It is therefore contemplated that the appended claims will
`cover any such modifications or any embodiments as fall
`within the true scope of the invention.
`What is claimed is:
`1. A word line driver, comprising:
`a driver circuit for outputting a plurality of word line
`activation signals, at least one of which has a pumped
`voltage level;
`
`5
`
`25
`
`30
`
`35
`
`40
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`unwa
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`60
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`6
`a plurality of groupsof first conductivity type transistors,
`each group havingits first conductivity type transistors
`controlled based on a respective decode signal having
`first and second logic levels both of which are lower
`than the pumped voltagelevel, one of the groups of the
`first conductivity type transistors being activated in
`response to the decode signal so as to output the word
`line activation signals; and
`a plurality of groups of second conductivity type transis-
`tors, each group having its second conductivity type
`transistors controlled based on a drivesignal having the
`pumped voltage level and a predetermined voltage
`level respectively opposite in phase to the decode
`signal, said second conductivity type transistors being
`respectively parallel-connected to said first conductiv-
`ity type transistors, and one of said groups of second
`conductivity type transistors being activated so as to
`output the word line activation signals.
`2. The word line driver as claimed in claim 1, further
`includinga plurality of level shifters for outputting the drive
`signals, each level shifter comprising:
`a switching circuit controlled based on the decodesignal
`and activated so as to send the predetermined voltage
`level to said second conductivity type transistors in
`response to the decode signal having the second logic
`level, and
`a latch circuit receiving the decode signal and latching
`and outputting the drive signal having the pumped
`voltage level to said second conductivity type transis-
`tors in response to the decode signal having thefirst
`logic level.
`3. A word line driver according to claim 1, wherein the
`first conductivity-type transistors are NMOStransistors and
`the second conductivity-type transistors are PMOStransis-
`tors.
`‘
`4. A word line driver, comprising:
`a driver circuit for generating a pumped voltage;
`a level shifter for outputting a level shifted signal
`response to a decodesignal;
`an output circuit including a first transistor of a first
`conductivity-type and a second transistor of a second
`conductivity-type, the second transistor being parallel
`connected to the first transistor, one of the first and
`second transistors being controlled based on the level
`shifted signal and the other of the. first and second
`transistors being controlled based on the decodesignal
`so as to together provide a path for coupling the driver
`circuit to a wordline.
`5. A word line driver according to claim 4, wherein the
`first conductivity-type transistor is an NMOStransistor and
`the second conductivity-type transistor is a PMOStransistor.
`6. A word line driver as claimed in claim 4, wherein the
`level shifted signal is opposite in phase to the decodesignal.
`7. A word line driver as claimed in claim 6, further
`comprising a third transistor controlled based on the level
`shifted signal and connected between the word line and a
`ground voltage.
`8. A word line driver, comprising:
`a driver circuit for outputting a plurality of word line
`activation signals, at least one of which has a pumped
`voltage level;
`a plurality of groupsof output circuits, each output circuit
`having a first conductivity-type transistor and a second
`conductivity-type transistor parallel-connected to the
`first conductivity-type transistor,
`wherein the first conductivity-type transistors of each
`group are controlled based on a respective decode
`
`in
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`8
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`5,602,796
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`7
`signal corresponding to the group, the decode signal
`having first and second logic levels both of which are
`lower than the pumped voltage level, the first conduc-
`livity-type transistors of one of the groups being acti-
`vated in responseto the decodesignal so as to pass the
`wordline activation signals output by the driver circuit
`to corresponding word lines, and
`wherein the second conductivity-type transistors of each
`group are controlled based on a corresponding drive
`signal having first and second voltage levels which are
`opposite in phase to the decode signal that corresponds
`to the group, oneof the first and second voltage levels
`being higherthan the first and secondlogic levels, and
`the second conductivity-type transistors of one of the
`groups being activated so as to pass the word line
`activation signals output by the driver circuit to corre-
`sponding wordlines.
`9. A word line driver according to claim 8, wherein the
`first conductivity-type transistors are NMOStransistors and
`the second conductivity-type transistors are PMOStransis-
`tors.
`
`10. A word line driver as claimed in claim 8, further
`including for each group a respective level shifter for
`outputting the drive signal to the second conductivity-type
`transistors of the group, each level shifter comprising:
`a switching circuit controlled based on the decode signal
`corresponding to the group, the switching circuit being
`activated so as to send the second voltage level to the
`second conductivity-type transistors of the group when
`the corresponding decode signal has the second logic
`level, and
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`20
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`a latch circuit receiving the decode signal and latching
`and outputting the drive signal to the second conduc-
`tivity-type transistors in response to the decode signal
`having the first logic level, when the drive signal has
`the first voltage level.
`it. A word line driver, comprising:
`a driver circuit for outputting a plurality of word line
`activation signals, at least one of which has a pumped
`voltage level;
`a level shifter for outputting a level shifted signal
`response to a decode signal; and
`a plurality of output circuits each including
`a first conductivity-type transistor forming, in response to
`the decode signal, a signal path for sending one of the
`word line activation signals to a corresponding word
`line, and
`
`in
`
`a second conductivity-type transistor forming, in response
`to the level shifted signal, a signal path for sending said
`one ofthe wordline activation signals to said word line.
`12. A word line driver according to claim 11, wherein each
`first conductivity-type transistor is a NMOStransistor and
`each second conductivity-type transistor is a PMOStransis-
`tor.
`
`13. A word line driver as claimed in claim 11, wherein the
`drive signal and the decode signal are opposite to each other
`in phase.
`
`9
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