Apparatuses and methods for single-ended global and local input/output architecture

Apparatuses, systems, and methods for single-ended global and local input/output architecture. A conventional memory may use local input/output (LIO) and global input/output (GIO) lines which are paired and carry complimentary signals. The present disclosure includes single ended LIO and GIO architecture where a single LIO couples a single GIO between a read/write amplifier and bit line as part of an access operation. This may reduce a footprint of the memory device.

BACKGROUND

This disclosure relates generally to semiconductor devices, and more specifically to semiconductor memory devices. In particular, the disclosure relates to volatile memory, such as dynamic random access memory (DRAM). Information may be stored on individual memory cells of the memory as a physical signal (e.g., a charge on a capacitive element). When accessed, the memory cell may be coupled to a digit line (or bit line), which in turn may be coupled to a sense amplifier. Along with the digit line coupled to the memory cell, a second, complimentary digit line may also be coupled to the sense amplifier. These complimentary digit lines may in turn be coupled to complimentary local input/output lines and complimentary global input/output lines. The use of complimentary signal lines may be useful for providing a reference voltage level to better distinguish the value being read from/written to the memory cell, but at the cost of increased space and power consumption, as transistors are needed for both lines. There is increasingly a need for memory devices with reduced size and memory consumption.

DETAILED DESCRIPTION

Memory devices may include a memory array which includes a number of memory cells, each of which may store information. For example, each memory cell may store a single bit of information. The memory cells may be located at the intersections of word lines (rows) and digit lines (bit lines/columns). Each word line may be associated with a row address, and each digit line may be associated with a column address. Accordingly, memory cells may be specified by their row and column addresses. When a memory cell is accessed (e.g., a read or write operation), the memory cell may be coupled via the bit line to a sense amplifier. For example in a read operation, the value stored in the memory cell (e.g., as a capacitive charge) may change a voltage of the bit line. The sense amplifier may detect this change, amplify the voltage to a system level (e.g., a voltage which represents logical high or a voltage which represents logical low) and then provide those voltages along a local input/output line (LIO) and global input/output line (GIO) to read/write amplifiers, which in turn may send the voltage to data terminals of the memory. During an example write operation, the process may generally be reversed (e.g., from GIO to LIO, to sense amplifier to bit line to memory cell).

In a conventional memory device, the sense amplifier, LIO and GIO may use a complimentary, double-ended architecture. In a double-ended architecture, the sense amplifier may be coupled to a first digit line, which is coupled to the accessed memory cell, and a second digit line. The second digit line may have a value which is complimentary to the value of the first digit line. For example, if a logical high is read from the accessed memory cell, the sense amplifier may drive the first digit line to a first voltage which represents a logical high, and the second digit line to a second voltage which represents a logical low. These voltages may then be read out along a pair of complimentary LIO lines, and a pair of complimentary GIO lines. The use of complimentary signals and signal lines may be useful for differentiating between different voltages (e.g., by comparing the complimentary values). However the additional signal lines, and the transistors to operate that second signal line, may take up additional space on the memory device.

The present disclosure is drawn to apparatuses, systems, and methods for single-ended LIO and GIO memory devices. In an example memory device of the present disclosure, there may be a single LIO and GIO. Accordingly, during an example read operation, the sense amplifier may drive a first digit line and second digit line to complimentary voltages, but only one voltage is coupled to the LIO (and in turn to the GIO). During an example write operation, a voltage may be provided along the GIO and LIO and the sense amplifier may drive the voltages of the first and the second bit line based on the voltage on the LIO. The use of a single-ended architecture (e.g., no second complimentary LIO and GIO) may allow for space saving, as the second GIO and LIO may be omitted. In addition, as explained in more detail herein, further space saving may be achieved by using a control architecture for the GIO and LIO which may take up less space/power than the control architecture used in conventional double ended architectures. The present disclosure may also relate to a method of operating the read and write circuits of a single ended LIO/GIO architecture which may reduce the space required (e.g., by reducing the number of transistors) for read and write circuits.

FIG.1is a block diagram of a semiconductor device according an embodiment of the disclosure. The semiconductor device100may be a semiconductor memory device, such as a DRAM device integrated on a single semiconductor chip.

The semiconductor device100includes a memory array118. The memory array118is shown as including a plurality of memory banks. In the embodiment ofFIG.1, the memory array118is shown as including eight memory banks BANK0-BANK7. More or fewer banks may be included in the memory array118of other embodiments. Each memory bank includes a plurality of word lines WL, a plurality of bit lines BLT and BLB, and a plurality of memory cells MC arranged at intersections of the plurality of word lines WL and the plurality of bit lines BLT and BLB. The selection of the word line WL is performed by a row decoder108and the selection of the bit lines BLT and BLB is performed by a column decoder110. In the embodiment ofFIG.1, the row decoder108includes a respective row decoder for each memory bank and the column decoder110includes a respective column decoder for each memory bank. The bit lines BLT and BLB are coupled to a respective sense amplifier (SAMP). Read data from the bit line BLT or BLB is amplified by the sense amplifier SAMP, and transferred to read/write amplifiers120over local data lines (LIO), transfer gate (TG), and global data lines (GIO). Conversely, write data outputted from the read/write amplifiers120is transferred to the sense amplifier SAMP over the complementary main data lines GIO, the transfer gate TG, and the complementary local data lines LIO, and written in the memory cell MC coupled to the bit line BLT or BLB.

The semiconductor device100may employ a plurality of external terminals, such as solder pads, that include command and address (C/A) terminals coupled to a command and address bus to receive commands and addresses, clock terminals to receive clocks CK and /CK, data terminals DQ coupled to a data bus to provide data, and power supply terminals to receive power supply potentials VDD, VSS, VDDQ, and VSSQ.

The clock terminals are supplied with external clocks CK and/CK that are provided to an input circuit112. The external clocks may be complementary. The input circuit112generates an internal clock ICLK based on the CK and /CK clocks. The ICLK clock is provided to the command decoder106and to an internal clock generator114. The internal clock generator114provides various internal clocks LCLK based on the ICLK clock. The LCLK clocks may be used for timing operation of various internal circuits. The internal data clocks LCLK are provided to the input/output circuit122to time operation of circuits included in the input/output circuit122, for example, to data receivers to time the receipt of write data. The input/output circuit122may include a number of interface connections, each of which may be couplable to one of the DQ pads (e.g., the solder pads which may act as external connections to the device100).

The C/A terminals may be supplied with memory addresses. The memory addresses supplied to the C/A terminals are transferred, via a command/address input circuit102, to an address decoder104. The address decoder104receives the address and supplies a decoded row address XADD to the row decoder108and supplies a decoded column address YADD to the column decoder110. The column decoder110may provide a column select signal CS, which may activate a selected one of the sense amplifiers SAMP. The address decoder104may also supply a decoded bank address BADD, which may indicate the bank of the memory array118containing the decoded row address XADD and column address YADD. The C/A terminals may be supplied with commands. Examples of commands include timing commands for controlling the timing of various operations, access commands for accessing the memory, such as read commands for performing read operations and write commands for performing write operations, as well as other commands and operations. The access commands may be associated with one or more row address XADD, column address YADD, and bank address BADD to indicate the memory cell(s) to be accessed.

The commands may be provided as internal command signals to a command decoder106via the command/address input circuit102. The command decoder106includes circuits to decode the internal command signals to generate various internal signals and commands for performing operations. For example, the command decoder106may provide a row command signal to select a word line and a column command signal to select a bit line.

The device100may receive an access command which is a read command. When a read command is received, and a bank address, a row address and a column address are timely supplied with the read command, read data is read from memory cells in the memory array118corresponding to the row address and column address. The read command is received by the command decoder106, which provides internal commands so that read data from the memory array118is provided to the read/write amplifiers120. The read data is provided along the data bus and output to outside from the data terminals DQ via the input/output circuit122.

The device100may receive an access command which is a write command. When the write command is received, and a bank address, a row address and a column address are timely supplied with the write command, write data supplied to the data terminals DQ is provided along the data bus and written to a memory cells in the memory array118corresponding to the row address and column address. The write command is received by the command decoder106, which provides internal commands so that the write data is received by data receivers in the input/output circuit122. Write clocks may also be provided to the external clock terminals for timing the receipt of the write data by the data receivers of the input/output circuit122. The write data is supplied via the input/output circuit122to the read/write amplifiers120, and by the read/write amplifiers120to the memory array118to be written into the memory cell MC.

The device100may also receive commands causing it to carry out one or more refresh operations as part of a self-refresh mode. In some embodiments, the self-refresh mode command may be externally issued to the memory device100. In some embodiments, the self-refresh mode command may be periodically generated by a component of the device. In some embodiments, when an external signal indicates a self-refresh entry command, the refresh signal AREF may also be activated. The refresh signal AREF may be a pulse signal which is activated when the command decoder106receives a signal which indicates entry to the self-refresh mode. The refresh signal AREF may be activated once immediately after command input, and thereafter may be cyclically activated at desired internal timing. The refresh signal AREF may be used to control the timing of refresh operations during the self-refresh mode. Thus, refresh operations may continue automatically. A self-refresh exit command may cause the automatic activation of the refresh signal AREF to stop and return to an IDLE state.

The refresh signal AREF is supplied to the refresh control circuit116. The refresh control circuit116supplies a refresh row address RXADD to the row decoder108, which may refresh one or more wordlines WL indicated by the refresh row address RXADD. In some embodiments, the refresh address RXADD may represent a single wordline. In some embodiments, the refresh address RXADD may represent multiple wordlines, which may be refreshed sequentially or simultaneously by the row decoder108. In some embodiments, the number of wordlines represented by the refresh address RXADD may vary from one refresh address to another. The refresh control circuit116may control a timing of the refresh operation, and may generate and provide the refresh address RXADD. The refresh control circuit116may be controlled to change details of the refreshing address RXADD (e.g., how the refresh address is calculated, the timing of the refresh addresses, the number of wordlines represented by the address), or may operate based on internal logic.

The power supply terminals are supplied with power supply potentials VDD and VSS. The power supply potentials VDD and VSS are supplied to an internal voltage generator circuit124. The internal voltage generator circuit124generates various internal potentials VPP, VOD, VARY, VPERI, and the like based on the power supply potentials VDD and VSS supplied to the power supply terminals.

The power supply terminals are also supplied with power supply potentials VDDQ and VSSQ. The power supply potentials VDDQ and VSSQ are supplied to the input/output circuit122. The power supply potentials VDDQ and VSSQ supplied to the power supply terminals may be the same potentials as the power supply potentials VDD and VSS supplied to the power supply terminals in an embodiment of the disclosure. The power supply potentials VDDQ and VSSQ supplied to the power supply terminals may be different potentials from the power supply potentials VDD and VSS supplied to the power supply terminals in another embodiment of the disclosure. The power supply potentials VDDQ and VSSQ supplied to the power supply terminals are used for the input/output circuit122so that power supply noise generated by the input/output circuit122does not propagate to the other circuit blocks.

FIG.2is a block diagram of an example layout of a memory device according to some examples of the present disclosure. The memory200may, in some embodiments, represent a layout of a portion of a memory array, such as the memory array118ofFIG.1. The memory200shows a representation of a portion of a memory array. The components shown inFIG.2may be repeated (e.g., tiled) across a memory array.FIG.2represents a simplified view of different regions across the surface of a chip. Additional components not shown inFIG.2may also be present in the memory array.

The memory200includes two array regions202and203, each of which includes a number of memory cells arranged at the intersection of word lines and bit lines. The array regions202and203are separated from each other by a sense amplifier (SA) region210. The SA region210includes sense amplifiers which selectively couple an accessed memory cell in one of the array regions202or203to a local input/output (LIO) line216. The SA region210includes a read/write gap (RW gap) regions212, which includes circuits used to selectively activate one or more of the sense amplifiers in the SA region210. Adjacent to each array region202and203is a respective sub-word line driver (SWD) region204and205respectively. The SWD regions204and205may include driver circuits which may activate word lines of the array region as part of an access operation. The SWD regions204and205may be separated by a minigap region214.

During an access operation on an example memory cell in the first memory array region202, the SWD204may activate a word line WL based on signals from a row decoder (e.g.,108ofFIG.1). The memory cell may lie at the intersection of the word line WL and a bit line BLB. A sense amplifier in the SA region210to be coupled to the bit line BLB and also a complimentary bit line BLT in the other array region203. The RW gap212may include circuits which control the timing and operation of the sense amplifier to amplify a voltage along BLB based on the signal read out from the activated memory cell. Selection circuits (such as those in the SA region210) may receive a column select signal CS (e.g., from a column decoder110ofFIG.1) which may couple the bit line BLT to the LIO line216.

The SA region210may have a width d1in an x direction. The RW gap212has a width d2in the x direction. The distance d1may be reduced compared to a memory which uses two LIO lines per SA region. Similarly the distance d2may be reduced compared to a memory where the RW gap212needs to include circuits which operate two different LIO lines. This may help reduce the footprint of the memory array. In addition, the minigap214may have a width in the x direction based on the width of the SA210(e.g., a width based on d1) and a height in the y direction based on the height of the SWD d3. Accordingly if the present disclosure which reduces the distance d1is coupled with SWDs of reduced height, they may synergize to further reduce the footprint of the memory beyond the reduction achieved by the narrowed distance d1.

FIG.3is a block diagram of a memory array according to some embodiments of the present disclosure. The memory array300may, in some embodiments, be included in the memory100ofFIG.1and/or200ofFIG.2. The memory array300shows a view of a memory which illustrates how a global input/output (GIG) line and column select (CS) are coupled to different sense amplifier regions across the memory array300.

The memory array300includes a number of core or array regions302(e.g.,202and203ofFIG.2) which are separated from each other by sense amplifier regions304(e.g.,210ofFIG.2). Each sense amplifier region304includes a LIO line, which is coupled to the GIG line310. A CS line312couples column select signals into the sense amplifier regions304. The GIO line310may couple information between the sense amplifier regions304and the RW amplifiers (e.g.,120ofFIG.1), not shown.

As may be seen fromFIG.3, there may be several LIO lines all coupled to the same GIO. In some embodiments, there may also be more than one GIO. Accordingly, references to single-ended architecture, or to a single LIO used as part of an access operation, should not be interpreted as requiring that there be only one LIO on the device.

FIG.4is a schematic diagram of selection architecture of a memory device according to some embodiments of the present disclosure. The architecture400represents a path from a read write amplifier402to a bit line BLB (and from there to the memory cell). The diagram of the architecture400represents a simplified view in which many components have been omitted. For example, in the sense amplifier430, a large number of components have been omitted for the sake of clarity while explaining the signal which couple the bit line BLB to the LIO. An example sense amplifier is explained in more detail inFIG.8. The architecture400also represents a specific division of components between different regions of the memory array, however other arrangements are possible in other example embodiments.

The present disclosure may generally be described with respect to information read to and written from a bit line BLB, which may store a complimentary value to a ‘true’ bit line BLT. Accordingly, the LIO may be labelled as a complimentary line LIOf and the GIO may be labelled as a complimentary GIOf. However it should be understood that these are merely conventions, and that other embodiments may involve coupling to the bit line BLT in which case the naming conventions LIO and GIO may be used. The labels LIOf and GIOf may be used to indicate that access operations are described with respect to the bit line BLB. However, it should be understood that there is no complimentary line to GIOf and LIOf in the single-ended architecture of the present disclosure, and the use of the ‘f’ is only a naming convention and is not meant to indicate a contrast to another GIO and LIO line.

The architecture400shows a RW amplifier402(e.g.,120ofFIG.1) which is coupled via a GIOf404to components in an RW gap region410(e.g.,212ofFIG.2) and minigap region420(e.g.,214ofFIG.2) to a sense amplifier430(e.g., in SA region210ofFIG.2) and through the sense amplifier430to a bit line BLB which couples to a memory cell. Each of the regions410,420and430include transistors which may be operated to selectively couple information to and from the bit line BLB, and which may also be used to couple one or more signal lines to system voltages such as VPERI and VSS, for example to precharge the LIOf.

The RW driver402is coupled to the GIOf404, which couples into the RW gap410of a particular SA region. The GIOf404may have several transistors403along its length, which have anode coupled to the GIOf. The transistors403may represent other connections to the GIOf404. For example, the transistors403may represent write select transistors (e.g.,412) or other components in the RW gap410(e.g., transistor414). For the sake of clarity in the drawing other components and details are not shown with respect to these other transistors403.

The GIOf404is coupled to circuits of the RW gap410. The GIOf404may be coupled in common to the node of a first transistor412and a second transistor414. The first transistor412has a node coupled to the LIOf406and a gate coupled to a write select signal SelWr. Accordingly, as part of a write operation, when the signal SelWr is active, the GIOf404is coupled to the LIOf406. The transistor414has a node coupled to the node of transistor416and to a node of transistor422in the minigap region420, and a gate coupled to a signal gio_gate. The transistor416has a node coupled to a ground voltage (e.g., VSS) and a gate coupled to a select read signal SelRd416. Accordingly, as part of a read operation, when SelRd is active, the transistor416couples the node of transistors414and the node of transistor422to ground. This may activate an inverter formed by transistors422and429. The transistors412,414, and416may be n-type transistors in some embodiments.

In the minigap region420, transistors424and426may be used to control a voltage along the LIOf406. Transistor424has a node coupled to LIOf406, a node coupled to the system voltage VPERI and a gate coupled to a signal LIOEQf. The transistor424may be a p-type transistor. Accordingly, when the signal LIOEQf is at a voltage representing a logical low (e.g., inactive), the transistor424may be active and may couple the LIOf406to VPERI. The transistor426has a node coupled to the LIOf406, a node coupled to a voltage VBLP, and a gate coupled to the signal SAEQ. The transistor426may be an n-type transistor. Accordingly, when the signal SAEQ is active, the LIOf406may be coupled to the voltage VBLP.

The minigap region420also includes transistors422and429, each of which has a gate coupled to the LIOf406. The transistor422has a node coupled to a signal gio_gate and a node coupled to the node between transistors414and416in the RW gap region410. The transistor429has a node coupled to a node of a transistor428and a node coupled to the signal gio_gate. The transistor422may be an n-type transistor, while the transistor429may be a p-type transistor. Accordingly, when LIOf406is at a high logical level, the transistor422may couple the signal gio_gate to the node between transistor414and416. In which case if gio_gate is at a low logical level (e.g., at a ground voltage) then the transistor414may be inactive, and the GIOf may remain at a voltage representing a logical high (e.g., VPERI). The transistors422and429may act together as an inverter to invert the signal along LIO406to the signal gio_gate when the inverter is active (e.g., when the signals SelRd is high and LIOPSf is low).

When the LIOf406is at a low logical level, the transistor429may be active, and the voltage provided by transistor428may be provided to the gate of transistor414. However the transistor422may remain inactive, and so the node between transistors414and416is not coupled to gio_gate. The transistor428has a node coupled to VPERI, a node coupled to the node of transistor429, and a gate coupled to the signal LIOPSf. The transistor429may be a p-type transistor. Accordingly, when the signal LIOPSf is at a logical low, the voltage VPERI is coupled to the node of the transistor429(and potentially to gio_gate if the voltage on LIO406is a logical low).

In the sense amplifier region430, the LIOf406is coupled to a bit line BLB by transistor432. The transistor432has a node coupled to LIOf, a node coupled to BLB, and a gate coupled to a column select signal CS. The signal CS may be provided by a column decoder at an active level when information along the bit line BLB is accessed.

FIG.5is a schematic diagram of circuits related to a read operation according to some embodiments of the present disclosure. The read circuits500shows certain components used to operate a read operation from a bit line BLB to a global input/output GIOf. The read circuits500may, in some embodiments, represent a portion of the architecture400ofFIG.4.

A transistor502(e.g.,432ofFIG.4) has nodes coupled to the bit line BLB and the LIOf and a gate coupled to a column select signal CS. The transistor502may be an n-type transistor. When the signal CS is active, the bit line BLB may be coupled to LIOf. A transistor504(e.g.,424ofFIG.4) has nodes coupled to system voltage VPERI and the LIOf, and a gate coupled to equalization signal LIOEQf. The transistor504may be a p-type transistor. When the signal LIOEQf is low, the transistor may couple the voltage VPERI onto the local input/output LIOf. The transistor506(e.g.,412ofFIG.4) has nodes coupled to LIOf and GIOf, and a gate coupled to write select signal SelWr. The transistor506may generally be kept inactive during a read operation. A write operation is discussed in more detail inFIGS.8-10.

A transistor503(e.g.,428ofFIG.4) has nodes coupled between a system voltage VPERI and a node of transistor508. The transistor503has a gate coupled to a signal LIOPSf. The transistor503may be a p-type transistor and accordingly, when the signal LIOPSf is at a low level, the transistor503may be active, coupling the voltage VPERI to a node of the transistor508. The transistor508(e.g.,429ofFIG.4) has nodes coupled between a node of the transistor503(which may be supplying the voltage VPERI if the signal LIOPSf is at a low logical level) and a signal gio_gate. The transistor508may be a p-type transistor and may have a gate coupled to LIOf. The transistor512(e.g.,416ofFIG.4) has a first node coupled to a ground voltage and a second node coupled to a node of transistor510and anode of transistor514. The transistor512may be an n-type transistor with a gate coupled to a select read signal SelRd. Accordingly, when the signal SelRd is at a high logical level (e.g., during a read operation), the nodes of transistors510and514may be coupled to aground voltage. The transistor510(e.g.,422ofFIG.4) has nodes coupled between the transistor512(which may supply a ground voltage during a read operation) and the signal line carrying gio_gate. The transistor510(e.g.,422ofFIG.4) may be an n-type transistor, with a gate coupled to LIOf. A transistor514(e.g.,414ofFIG.4) has nodes coupled between the transistor512(which may provide a ground voltage during a read operation) and the GIOf. The transistor514may be an n-type transistor with a gate coupled to gio_gate.

Accordingly, the transistors508and510may act as an inverter for the voltage along LIOf to a voltage of the signal gio_gate when the transistors503and512are active (e.g., when the signal LIOPSf is low and the signal SelRd is high). If the voltage on LIOf is high (e.g., because a high logical value is read from BLB), then transistor510may be active and the voltage gio_gate may be coupled to ground. If the voltage on LIOf is low (e.g., because a low logical value is read from BLB), then transistor508may be active and the voltage gio_gate may be coupled to VPERI, which may in turn activate the transistor514to couple GIOf to ground. Accordingly, when the voltage LIOf is low, the voltage GIOf may also be driven low.

As part of a read operation, the line GIOf may be pre-charged to a voltage which represents a high logical level. If the voltage along the LIOf is a high logical level (e.g., a voltage such as VPERI), the voltage gio_gate may be low, and the transistor514may remain inactive. Accordingly, the GIOf may remain at the voltage which represents a high logical level. If the voltage along LIOf is at a low logical level (e.g., a ground voltage), then the voltage gio_gate may be at a high level, and the transistor514may be active, coupling the GIOf to ground (which represents a low logical level).

FIGS.6and7are graphs showing example read operations according to some embodiments of the present disclosure. The graph600ofFIG.6shows an example operation where a low logical level is read out from the memory cell coupled to BLB, while the graph700ofFIG.7shows an example operation where a high logical level is ready out from the memory cell coupled to BLB. The graphs ofFIGS.6and7may, in some embodiments, represent the operation of read architecture of a memory as described inFIGS.4and5. For the sake of clarity, reference will be made to the components and reference numbers ofFIG.5to describe the relationship between the signals inFIGS.6and7.

The graph600ofFIG.6shows an initial time t0when a read operation begins. The signal CS rises to an active level, which couples the bit line BLB to the local input/output LIOf. Accordingly, starting at t0, the voltage on LIOf begins to fall. Around the initial time to, the signal LIOPSf is driven to a low level (e.g., to activated the transistor503and couple the inverter formed by transistors508and510to the voltage VPERI), and the signal LIOEQf rises to an active level, to inactivate the transistor504. The switching of various signals may cause the voltage on BLB to rise a bit as it is coupled to the higher voltage along the LIOf, even as the voltage along LIOf falls.

At a time t1, the signal SelRd may also become active to activate the transistor512and couple the inverter formed by transistors508and510to a ground voltage. This may cause the voltage gio_gate to begin to rise, as the inverter is now powered, and the voltage along LIOPSf is low. The rising voltage along gio_gate activates transistor514, which in turn couples GIOf to ground (via the transistor512). This causes the voltage on GIOf to fall, which may be read by the RW amplifier as a low logical level (e.g., the value read out from the memory cell coupled to BLB).

The graph700ofFIG.7shows an example read operation similar to the one shown inFIG.6, except that inFIG.7the value read is a high logical value. Since many features may be similar, for the sake of brevity, features similar to those already described with respect toFIG.6will not be repeated again with respect toFIG.7.

In the graph700, the read operation begins at the time t0with the signals LIOEQf and CS rising to active levels, while the signal LIOPSA falls to a low logical level. The voltage BLB is at a high logical level, as the memory cell coupled to BLB is reading out a high value. Accordingly, the voltage on LIOf remains high. At a time t1, the signal SelRd rises to a high logical level, which powers the inverter. This causes the voltage of gio_gate to fall, since the input voltage to the inverter LIOf is high. Since the voltage gio_gate is low, the transistor514remains inactive, and the voltage of GIOf stays high. A read write amplifier may read the high voltage along GIOf as a high logical level.

FIG.8is a schematic diagram of a sense amplifier according to some embodiments of the present disclosure. The sense amplifier800may, in some embodiments, be included in the sense amplifier SAMP ofFIG.1and/or the sense amplifier regions210ofFIGS.2,304, and/or430ofFIG.4. The sense amplifier800selectively amplifies a signal on the bit lines BLB and BLT. The sense amplifier800will generally be described with respect to a write operation (e.g., a signal on LIO being written to a memory cell along BLB). However, it should be understood that the sense amplifier800may also be used as part of a read operation.

The sense amplifier800may be coupled to a pair of complimentary bit lines BLB and BLT, but only a single LIO (here labelled LIOf). Since a write select transistor (e.g.,412ofFIG.4) is active due to the signal SelWr being active, the LIOf may be coupled to a GIOf, and from there to a read write amplifier. Accordingly, the voltage on the GIOf may be written through the LIOf to the bit line BLB, and the sense amplifier800may set the voltage on the bit lines BLB and BLT based on the voltage along LIOf.

The sense amplifier800includes a pair of isolation transistors810and812. These isolation transistors810and812may be coupled to respective isolation signals ISOB and ISOT respectively. The two isolation signals ISOB and ISOT may be operated independently from each other as part of a write operation. This may allow the signal from the single LIO (e.g., LIOf) to be written to the two complimentary bit lines BLB and BLT.

A first transistor802(e.g., transistor432ofFIG.4) may be activated by a column select signal CS to couple LIOf to the bit line BLB. The transistor802has a node coupled to the bit line BLB, a node coupled to LIOf, and a gate coupled to the column select signal CS. The transistor802may be an n-type transistor.

The sense amplifier800includes p-type transistors P1822and P2823and n-type transistors M1824and M2826. The transistor P1822has a node coupled to a signal ACT, a node coupled to a node GutB, and a gate coupled to a node GutT. The node GutB may be coupled through a transistor832to the bit line BLB, and the node GutT may be coupled through a transistor833to the bit line BLT. The transistors832and833may be inactive during write operation. The transistor P2823has a node coupled to ACT, a node coupled to node GutT, and a gate coupled to node GutB. The transistor M1has a node coupled to the node GutB, a node coupled to the signal RNL, and a gate coupled to the bit line BLT. The transistor M2has a node coupled to the node GutT, a node coupled to the signal RNL, and a gate coupled to the bit line BLB. During access operations, the signals ACT and RNL may be set to system voltages which represent a logical high and a logical low value, respectively.

A first isolation transistor810is coupled between the bit line BLB and the node GutB. The first isolation transistor810has a gate coupled to a signal ISOB. The first isolation transistor810may act as a switch and may couple the bit line BLB to the node GutB when the signal ISOB is active. The first isolation transistor810may be an n-type transistor which is active when the signal ISOB is at a logical high. The sense amplifier also includes a second isolation transistor812, analogous to the first isolation transistor810. The second isolation transistor812is coupled between the bit line BLT and the node GutT, with a gate coupled to a signal ISOT. When the signal ISOT is active, the second isolation transistor812couples the bit line BLB806to the gut node GutT.

The isolation transistors810and812may be operated separately during a write operation to help prevent conflicts between the signal provided to the bit line BLB as part of a write operation and the states of P1and M1. For example, during an example write operation, if the bit line BLB is being written to a high value (e.g., from a 0 to a 1) the bit line BLB may cause a conflict with M1if the transistor810is active. Similarly, during an example write operation where a low value is being written (e.g., BLB is going from a voltage representing a logical high to a voltage representing a logical low) the pull down of BLB may present a conflict with P1if the transistor810is active. Accordingly, the signal ISOB may be pulsed inactive during a write operation to prevent these conflicts. The operation of the sense amplifier during example write operations is discussed in more detail inFIGS.9and10.

FIGS.9and10are timing diagram of example write operations in a sense amplifier according to some embodiments of the present disclosure.FIG.9shows a write operation where a logical low value is written to the bit line BLB, which in turn causes a logical high to be written to BLT.FIG.10shows an example write operation where a logical high is written to the bit line BLB, which in turn causes a logical low to be written to the bit line BLT. In explaining the operations shown inFIGS.9and10, reference will be made to features discussed inFIGS.4,5, and8.

FIG.9shows a graph900of different signals in an example sense amplifier, such as the sense amplifier800ofFIG.8, during a write operation where a logical low is written to the bit line BLB. Before an initial time t0, the voltage on the GIOF begins falling from a voltage which represents a high logical value to a voltage which represents a low logical value. At the initial time t0, a signal ISOB is driven from a high logical level to a low logical level. This may inactivate the first isolation transistor810, decoupling the bit line BLB804from the gut node GutB. The signals LIOEQf, CS, and SelWr may rise from a low logical level to a high logical level. The signal LIOEQf may inactivate transistor424, which may decouple the LIOf from the voltage VPERI. The signal SelWr becoming active may instead couple LIOf to the signal along GIOf by activating the transistor412. The column select signal CS may activate transistor432and couple the LIOf to the bit line BLB. Note that throughout the write operation, while the signal ISOB changes from high to low to high, the signal ISOT remains high.

At a first time t1, the voltage on BLB begins to fall, as the falling voltage on GIOf is coupled to the bit line BLB through the LIOf. The falling voltage on BLB may cause the transistor826to inactivate, which may decouple the voltage GutT from the signal RNL (which may be a voltage representing a logical low. Since the transistor812is still active (e.g., since ISOT remains high), the voltage BLT may be coupled to the voltage of GutT.

At a second time t2, the isolation signal ISOB may begin to rise to an active level again. The isolation signal ISOB may activate the transistor810, which may couple the falling voltage on BLB to the node GutB. The falling voltage on GutB may in turn activate transistor823, which may couple the signal ACT (set to a system voltage representing a high logical level) to the voltage GutT. Since the node GutT was previously uncoupled from the low logical voltage on RNL as the voltage BLB fell and transistor826was inactivated, this may cause the voltage on the node GutT to be quickly pulled up to the voltage on ACT, which is shown beginning between the times t2and t3. Accordingly, as the voltage on BLB falls and the voltage on BLT rises, the transistors826may be inactive, which allows the voltage on the bit line BLT to be driven up by the activated transistor823, while the transistor824may become active, further driving the bit line BLB and the node GutB to a low voltage. At the time t3, the voltages on the bit lines BLT and BLB may cross (e.g., after the time t3, the voltage of BLB may be lower than the voltage of BLT). This may represent that the state of the bit lines has switched, and that the low logical value has been written to the bit line BLB, while a high value has been written to the bit line BLT.

FIG.10is a graph1000of an example write operation where the bit line BLB is driven from a low logical level to a high logical level. Since the graph1000may be broadly similar to the graph900ofFIG.9, for the sake of brevity features and operations similar to those described with respect toFIG.9will not be repeated again forFIG.10.

The graph1000shows that at a time t0, the control signals LIOEQf, SelWt, and CS all become active, while the isolation signal ISOB is pulsed inactive. In contrast to the graph900, in the graph1000, the GIOf remains at a high voltage, as does the LIOf, since a high value is being written to BLB. Accordingly, shortly after the time t0, the voltage on BLB begins rising, which at the time t1, causes the voltage on BLT to begin falling. After the time t2, the voltages on BLB and BLT cross, with the voltage on BLT being lower than the voltage on BLB, indicating that a high value has been written to the bit line BLB.

FIG.11is a schematic diagram of a voltage selector according some embodiments of the present disclosure. The voltage selector1100may select a voltage for a VYS power bus, which in turn may be used to set the voltage of a column select signal CS, which is applied to the gate of a column select transistor (e.g.,432ofFIG.4,502ofFIG.5, and/or802ofFIG.8). This may be useful in different operations of the memory, as otherwise there may be situations where the driving effect of the CS transistor is weak if the input to the CS transistor (e.g., BLB in a read operation or LIOf in a write operation) and the voltage of the CS signal are both high.

The voltage selector1100includes a number of transistors1102-1106, each of which acts a switch to couple a different voltage to a VYS power bus, which is used to determine the voltage level of the signal CS when it is active. Each transistor1102-1106has nodes coupled between a respective voltage and the VYS power bus. Each transistor1102-1106has a gate coupled to a different control signal. Since in the example ofFIG.11p-type transistors are used, which of the control signals is at a low logical level may determine which voltage is coupled. So a signal Vys2VaryF is used to provide a voltage Vary, a signal Vys2VddF is used to provide a voltage Vdd, and a signal VysWrt is used to provide a voltage Vyspp. The voltage Vary may be less than the voltage Vdd which may be less than Vyspp. In some embodiments, Vary may be about 1V, Vdd may be about 1.2 V, and Vyspp may be about 1.5 V.

The different control signals may be provided based on a signal from a mode register1110, and a state of a write operation provided by a write logic block1112. The mode register1110may provide a speed signal which may be at a high or low level based on the column address strobe (CAS) latency, or CL, set in the mode register. The speed signal may indicate if the memory is set up for high speed operations or not. The write block1112may provide a write in progress WIP signal which may indicate if a write operation is in progress.

NOR gate1114may provide a signal VysWrt at a low level (e.g., providing the voltage Vyspp as the voltage on the VYS power bus) unless both the WIP and speed signal are at a low level. In other words, as long as either the memory is in a high speed mode, or a write operation is occurring, the voltage Vyspp may be provided as the voltage along the VYS power bus.

A first NAND gate1118provides the signal Vys2VaryF, and has a first input terminal coupled to the speed signal through an inverter1116and a second input terminal coupled to WIP through an inverter. The signal Vys2VaryF may only be provided at a low level when WIP is low and when speed signal is low. Accordingly, the voltage Vary may be provide along the VYS power bus when a write operation is not in progress and a slow CL is indicated by the mode register.

A second NAND gate1119has a first input terminal coupled to the speed signal and a second input terminal coupled through an inverter to the WIP signal. Accordingly, the signal Vys2VddF will only be provided at a low level when the speed signal is at a high level and the signal WIP is at a low level. Thus the voltage Vdd may be provided along the VYS power bus when a write operation is not in progress and a fast CL is indicated by the mode register1110.