Patent ID: 12217784

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reducing power consumption of electronics and computer systems is an ongoing goal. Accordingly, reducing the power consumption of dynamic random access memory (DRAM) devices is part of that effort. The main contributors to the power consumption of DRAM devices are associated with the formula P=CV2f, where P is power consumption, C is capacitance, V is the switching voltage, and f is the switching frequency. Thus, because the voltage is squared in the preceding formula, reducing the switching voltage can have an important effect on reducing the power consumption.

In an embodiment, the dynamic memory array(s) of a DRAM device are operated using at least two voltages. The first voltage, which is used to power the sense amplifiers during sense (i.e., read) operations and most other column operations (e.g., precharge, activate, write), is the operating (i.e., switching) voltage of a majority of the digital logic circuitry of the DRAM device. The second voltage, which determines the voltage written to the capacitor of the DRAM cells (i.e., bitline voltage) is greater than the operating (i.e., switching) voltage of a majority of the digital logic circuitry of the DRAM device. In other words, the digital logic circuitry is operated using a supply voltage that is lower than the voltage written to the capacitors of the DRAM array. This allows lower voltage swing (and thus lower power) digital logic to be used for a majority of the logic on the DRAM device while writing a larger voltage to the DRAM cells for retention time purposes. The lower voltage swing used by the majority of the logic reduces the power consumption of the sense amplifiers of the DRAM array and the other digital logic of the DRAM which, in turn, reduces the power consumption of the DRAM device as a whole.

FIG.1is a block diagram illustrating a dynamic random access memory (DRAM) system according to an embodiment. InFIG.1, memory system100includes DRAM memory device110and controller180. Controller180and memory device110are integrated circuit type devices, such as are commonly referred to as a “chips”. A memory controller, such as controller180, manages the flow of data going to and from memory devices. A memory controller can be a separate, standalone chip, or integrated into another chip. For example, a memory controller may be included on a single die with a microprocessor, or included as part of a more complex integrated circuit system such as a block of a system on a chip (SOC).

Controller180includes physical interface185. Physical interface185includes command/address (CA) interface181and bidirectional data (DQ) interface182. Memory device110includes physical interface circuitry175. Physical interface circuitry175includes command/address (CA) interface171and bidirectional data (DQ) interface172. Command/address interface181of controller180is operatively coupled to CA interface171of memory device110to send commands and addresses to memory device110. Controller180is operatively coupled to memory device110via bidirectional data interface182. Controller180is operatively coupled to memory device110to communicate data with memory device110. Memory device110communicate data via bidirectional data interface172.

InFIG.1, DRAM memory device110includes multiple banks/sub-banks, control circuitry160and interface circuitry175. DRAM memory device110may be, be on, or comprise at least one integrated circuit. The DRAM banks include subarrays (e.g., subarray128), sense amplifier stripes (e.g., sense amplifier stripes135), column decode140, and wordline control circuitry150. The sense amplifier stripes135include sense amplifiers (e.g., sense amplifier130) and local-global switches (e.g., local-global switch127). The subarrays include memory bit cells (e.g., cell123). The memory bit cells123connect to wordlines122, bitlines121, and column select lines124. The sense amplifiers130connect to bitlines121and local data lines125. Local-global switches127connect to local data lines125and global data lines126.

Control circuitry160is operatively coupled to the DRAM banks to process at least column addresses, row addresses, and/or commands received via CA interface171. Control circuitry160is comprised of digital logic circuitry that operates, in a normal operating mode, using a selected (e.g., by the manufacturer of DRAM memory device110) digital logic supply voltage (a.k.a., VDD.) Control circuitry160may comprise a majority of circuitry implemented using complementary metal-oxide-semiconductor (CMOS) type logic gates. Control circuitry160may comprise a circuitry implemented using CMOS logic implemented in a high-K/metal gate (HKMG) CMOS fabrication process. The signal swings (i.e., between a logical ‘1’ and a logical ‘0’) of full-swing CMOS logic gates may range from a minimum corresponding to the negative supply/reference/substrate voltage up to a maximum voltage corresponding to the digital logic supply voltage.

In an embodiment, DRAM memory device110(and sense amplifiers130, in particular), in a normal operating mode (i.e., a non-test mode), senses the state of memory bit cells (e.g., cell123) using the digital logic supply and/or maximum signal swing level (with respect to the same negative supply/reference/substrate voltage as the bitline voltage is referenced to) of a majority of the digital logic on DRAM memory device110.

When writing data to the memory bit cells (e.g., cell123), however, DRAM device (and sense amplifiers130, in particular) may charge bitlines to a voltage (i.e., maximum voltage with respect to the negative supply/reference/substrate voltage) that is higher than the digital logic supply and/or maximum signal swing level (with respect to the same negative supply/reference/substrate voltage as the bitline voltage is referenced to) of a majority of the digital logic on DRAM memory device110. In particular, during write and writeback operations, bitlines121may be charged using a maximum voltage that is greater than control circuitry160. For brevity, this boosted bitline voltage may be referred to herein as VBLHI.

A normal operating (non-test) mode includes the expected operating modes for DRAM memory device110in a memory system100that is being used in a non-production and non-test environment. For example, DRAM memory device110may be tested or otherwise operated in one or more test mode before being included in a larger system (e.g., completed computer system, consumer electronic device, etc.) These test modes may be used during various manufacturing processes and/or stages, but are typically not used while the system is being used by an end user (e.g., consumer, data center, etc.)

Test modes may be used, for example, at times, such as during burn-in, to ‘stress’ DRAM device110in order to confirm the functioning and/or reliability of DRAM device110. Likewise, the digital logic supply voltage may be lowered below the boosted bitline voltage during testing to confirm the functioning and/or reliability of DRAM memory device110. However, test modes are not typically used during ‘normal’ operation because the functioning, performance, lifetime, and/or reliability of DRAM device110may be degraded while being operating in one or more test modes (as opposed to ‘normal’ operating modes.)

Sense amplifier stripes135and the sense amplifiers therein (e.g., sense amplifier130) may be operated, in a normal operating mode, using a selected (e.g., by the manufacturer) boosted bitline voltage (and/or bitline voltage range). Wordline control circuitry150may be operated, in a normal operating mode, using the digital logic supply voltage and/or a separate programming power supply voltage (VPP) that may be present to support word line voltage requirements that are compatible with the boosted bitline voltage. Column decode140may be operated, in a normal operating mode, using the digital logic supply voltage. Control circuitry (and included datapath circuitry)160may be operated, in a normal operating mode, using the digital logic supply voltage. Interface circuitry175may be operated, in a normal operating mode, using an input/output (I/O) supply voltage and/or the digital logic supply voltage.

In an embodiment, control circuitry160, column decode140, and row decode150collectively at least processes column addresses and row addresses to retrieve data stored in at least subarray128. Control circuitry160, column decode140, and row decode150operate using a digital logic supply voltage. Sense amplifiers130also operate using the digital logic supply voltage during sense operations and column operations. Sense amplifiers130also operate, during writeback operations, using a boosted bitline voltage that is greater than the first digital logic supply voltage. Control circuitry160, column decode140, and/or row decode150may be implemented using a high-k metal gate process.

Sense amplifiers130include a pair of cross-coupled inverters in a bi-stable flip-flop configuration coupled to respective bitlines of the dynamic memory array. These cross-coupled inverters each having a negative supply node and a positive supply node. During writeback operations, the boosted bitline voltage may be selectively coupled to the positive supply node of the cross-coupled inverters. This causes the sense amplifier circuits to charge the cells123of the array to the boosted bitline voltage rather than the digital logic supply voltage. Increasing the voltage that cells123are charged with increases the cells123data retention time when compared to charging the cells123with the digital logic supply voltage.

In an embodiment, the digital logic supply voltage is selectively coupled to the positive supply node of the cross-coupled inverters during sense operations and column operations. The digital logic supply voltage is selectively decoupled to from positive supply node of the cross-coupled inverters during writeback operations. In this manner, a drive-fight between the digital logic supply voltage and the boosted bitline voltage is avoided. In an embodiment, the boosted bitline voltage is selectively coupled to the positive supply node of the cross-coupled inverters during refresh operations. In particular, the boosted bitline voltage is selectively coupled to the positive supply node of the cross-coupled inverters during a sense operation without first sensing using the digital logic supply voltage. In this manner, a refresh operation may be completed without waiting for the cross-coupled inverters reaching a stable state using the digital logic supply voltage before beginning to charge the bitlines with the boosted bitline voltage. This may allow the refresh operation to complete in less time than a separate sense operation followed by a separate (boosted) writeback operation.

In an embodiment, the boosted bitline voltage may be based on a command received from controller180. For example, controller180may write a value to a register in control circuitry160that sets the boosted bitline voltage. In another example, the command (e.g., refresh, write, etc.) may indicate a boosted bitline voltage (e.g., write with boost, refresh without boost, etc.) In another example, controller180may indicate the boosted bitline voltage using a combination of a register in control circuitry160and a command that indicates a boosted bitline voltage. In an embodiment, controller180may select the boosted bitline voltage based on a temperature of memory device110. In an embodiment, controller may select the boosted bitline voltage based on a use for the data being sensed. For example, if controller180knows that the data is no longer going to be stored in memory device110, controller180may indicate a “read without boosted writeback” command. A “read without boosted writeback” or a “refresh without boosted writeback” command may select a bitline voltage for writeback that is equal to the digital logic supply voltage. These commands may affect (e.g., reduce) the processing time of commands and thereby increase the throughput of memory device110when compared to always using a boosted bitline voltage.

In an embodiment, memory device110may select the boosted bitline voltage. Memory device110may select the boosted bitline voltage based on the temperature of memory device110. In an embodiment, memory device110may select the boosted bitline voltage based on the temperature of memory device110and one or more indicators (e.g., register values or commands) received from controller180. For example, memory device110may select the boosted bitline voltage based on the temperature of memory device110and a temperature vs. boosted bitline voltage coefficient indicator received from controller180.

FIG.2is a diagram illustrating an example boosted writeback sense amplifier. Sense amplifier200may be part of DRAM memory device110and/or sense amplifier stripes135(i.e., as sense amplifier130, in particular.) InFIG.2, sense amplifier200includes functional blocks210,220,225,230,240, and250. Although illustrated inFIG.2as part of one sense amplifier200, functional blocks220,225,230,240, and250may be shared with multiple amplifier blocks210to form multiple sense amplifiers. Similarly, although illustrated inFIG.2in proximity to amplifier block210, functional blocks220,225,230,240, and250may be located at various locations within a DRAM array that are relatively remote to amplifier block210.

Sense amplifier200performs the evaluation of the voltage difference on the true (BLt) and complement (BLc) bitlines. Sense amplifier200also performs the writing and/or writeback of data to a memory cell (e.g. cell123) by forcing (charging) the true (BLt) and complement (BLc) bitlines to either the digital logic supply voltage (VDD) and/or a boosted bitline voltage (VBLHI).

Amplifier block210is comprised of a pair of cross-coupled inverters that are switched on by evaluate control block220. The cross-coupled inverters of amplifier block210comprise n-channel field effect transistors (NFETs)211and212, and p-channel field effect transistors (PFETs)213and214. NFET211and PFET214form a first inverter that is cross-coupled to a second inverter formed using NFET212and PFET214. The outputs of each inverter is provided to the input of the other inverter (i.e., cross-coupled). The negative supply and the positive supply to the inverters of amplifier block210are selectively provided by evaluate control block220and/or boosted bitline control block225.

The power supplies SAN and SAP to these inverters are selectively (switchably) provided to amplifier block210by evaluate control block220. The power supply SAP is selectively (switchably) provided to amplifier block210by boosted bitline control block225. The power supplies SAN and SAP to these inverters are selectively (switchably) provided to amplifier block210by evaluate control block220in order to allow the internal and external nodes of/to amplifier block210(including the bitlines BLt and BLc, and power supplies SAN and SAP) to be equalized and then activated to evaluate the voltages on the bitlines BLt and BLc. The power supply SAP is selectively (switchably) provided to amplifier block210by boosted bitline control block225in order to charge the voltage on an amplifier block210state dependent one of the bitlines BLt and BLc to the boosted bitline voltage VBLHI.

Evaluate control block220includes NFET221and PFET222. NFET221, under the control of the signal on the NSET node, switchable connects and disconnects the negative (reference) supply voltage to the node SAN (which is the negative supply for amplifier block210). PFET222, under the control of the signal on the PSET node, switchably connects and disconnects the digital logic supply voltage to the node SAP (which is the positive supply for amplifier block210). The signal provided to the NSET node (i.e., gate of NFET221) may have a swing that is less than the boosted bitline voltage. Thus, in normal operation, the control circuitry (e.g., control circuitry160) coupled to evaluate control block220may comprise circuitry that can supply the NSET node with a signal that reaches the digital logic supply voltage but does not reach VBLHI (or even reaches VBLHI minus PFET222's threshold voltage.)

In an embodiment, in normal non-writeback operations, the digital logic supply voltage connected to SAP by PFET222is less than the boosted bitline voltage VBLHI. The swing of the signal on PSET (i.e., the gate of PFET222) may be equal to (or less than a threshold voltage of PFET222lower than) the digital logic supply voltage (e.g., VDD) to be connected to SAP. Thus, in normal non-writeback operations, the control circuitry coupled to evaluate control block220may comprise circuitry that can supply the PSET node with a signal that reaches the digital logic supply voltage VDD but does not reach VBLHI (or even reaches VBLHI minus PFET222's threshold voltage.)

Sense amplifier equalize block230, when activated via a signal on node SNS_AMP_EQ connects SAP and SAN together and to an equalize supply voltage VBLEQ. Sense amplifier equalize block230includes NFETs231-233. The gates of NFETs231-233are operatively coupled together and to node SNS_AMP_EQ. The source and drain nodes of NFET231are connected to SAN and SAP, respectively. The source and drain nodes of NFET232are connected to SAN and VBLEQ, respectively. The source and drain nodes of NFET233are connected to VBLEQ and SAP, respectively. The signal provided to SNS_AMP_EQ may have a swing that is less than the boosted bitline voltage VBLHI. Thus, in normal operation, the control circuitry (e.g., control circuitry160) coupled to sense amplifier equalize block230may comprise circuitry that can supply the SNS_AMP_EQ node with a signal that reaches the digital logic supply voltage but does not reach VBLHI (or even does not reach VBLHI minus PFET222's threshold voltage.)

Bitline equalize block240, when activated via a signal on node EQL, connects the bitlines BLt and BLc together and to an equalize supply voltage VBLEQ. Bitline equalize block240includes NFETs241-243. The gates of NFETs241-243are operatively coupled together and to node EQL. The source and drain nodes of NFET241are connected to BLt and BLc, respectively. The source and drain nodes of NFET242are connected to BLt and VBLEQ, respectively. The source and drain nodes of NFET243are connected to VBLEQ and BLc, respectively. The signal provided to EQL may have a swing that is less than the boosted bitline voltage VBLHI. Thus, in normal operation, the control circuitry (e.g., control circuitry160) coupled to bitline equalize block240may comprise circuitry that can supply the EQL node with a signal that reached the digital logic supply voltage but does not reach VBLHI (or even does not reach VBLHI minus PFET222's threshold voltage.)

Column connect block250selectively (switchably) connects (a.k.a., gates) the bitlines BLt and BLc to local data lines LDQt and LDQc, respectively. Column connect block250includes NFETs251-252. The gates of NFETs251-252are operatively coupled together and to node CSL. The source and drain nodes of NFET251are connected to BLt and LDQt, respectively. The source and drain nodes of NFET252are connected to BLc and LDQt, respectively. The swing of the signal on CSL (i.e., the gates of NFETs251-252) may be equal to the digital logic supply voltage.

In an embodiment, PFET226, under the control of the signal on the PSETH node, switchably connects and disconnects the boosted bitline voltage VBLHI to the node SAP. PFET222, under the control of the signal on the PSET node, switchable disconnects the digital logic supply voltage VDD from the node SAP when PFET226connects the boosted bitline voltage VBLHI to the node SAP. To disconnect the digital logic supply voltage VDD from the node SAP, the voltage on the PSET node may be boosted to VBLHI. The disconnection of the digital logic supply voltage VDD from the node SAP avoids a drive-fight between the boosted bitline voltage VBLHI and the digital logic supply voltage VDD. When PFET226connects the boosted bitline voltage VBLHI to the node SAP, an amplifier block210state selected one of the bitlines BLt and BLc are charged to the boosted bitline voltage VBLHI. In an embodiment, PFET226connects the boosted bitline voltage VBLHI to the node SAP to evaluate the voltages on the bitlines BLt and BLc. In this embodiment, PFET226may connect the boosted bitline voltage VBLHI to the node SAP without first connecting the digital logic supply voltage VDD to the node SAP.

FIG.3is a diagram illustrating elements of an offset compensated boosted writeback sense amplifier. Sense amplifier300may be part of DRAM memory device110and/or sense amplifier stripes135(i.e., as sense amplifier130, in particular.) InFIG.3, sense amplifier300includes functional blocks310,320, and340. Other functional block of sense amplifier300have been omitted fromFIG.3for the sake of brevity. Sense amplifier300performs the evaluation of the voltage difference on the true (BLt) and complement (BLc) bitlines. Sense amplifier300also performs the writing and/or writeback of data to a memory cell (e.g. cell123) by forcing (charging) the true (BLt) and complement (BLc) bitlines to either the digital logic supply voltage (VDD) and/or a boosted bitline voltage (VBLHI).

Amplifier block310is comprised of a pair of cross-coupled inverters that are switched on by evaluate control block320. The cross-coupled inverters of amplifier block310comprise n-channel field effect transistors (NFETs)311and312, and p-channel field effect transistors (PFETs)313and314. NFET311and PFET314form a first inverter that is cross-coupled to a second inverter formed using NFET312and PFET314. The outputs of each inverter is provided to the input of the other inverter (i.e., cross-coupled). The negative supply and the positive supply to the inverters of amplifier block310are selectively provided by evaluate control block320.

The power supplies SAN and SAP to these inverters are selectively (switchably) provided to amplifier block310by evaluate control block320in order to allow the internal and external nodes of/to amplifier block310(including the bitlines BLt, BLc, internal nodes SABLt, SABLc, and power supplies SAN and SAP) to be equalized and then activated to evaluate the voltages on the bitlines BLt and BLc. The power supply SAP is selectively (switchably) provided to amplifier block310by boosted bitline control block325. The power supply SAP is selectively (switchably) provided to amplifier block310by boosted bitline control block325in order to charge the voltage on an amplifier block310state dependent one of the bitlines BLt and BLc to the boosted bitline voltage VBLHI.

Evaluate control block320includes NFET321and PFET322. NFET321, under the control of the signal on the NSET node, switchable connects and disconnects the negative (reference) supply voltage to the node SAN (which is the negative supply for amplifier block210). PFET322, under the control of the signal on the PSET node, switchable connects and disconnects the digital logic supply voltage VDD to the node SAP (which is the positive supply for amplifier block310). NFET321, under the control of the signal on the NSET node, switchable connects and disconnects the negative (reference) supply voltage to the node SAN (which is the negative/reference supply for amplifier block310. The signal provided to the NSET node (i.e., gate of NFET321) may have a swing that is less than the bitline voltage. Thus, in normal operation, the control circuitry (e.g., control circuitry160) coupled to evaluate control block320may comprise circuitry that can supply the NSET node with a signal that reaches the digital logic supply voltage VDD but does not reach VBLHI (or even reaches VBLHI minus PFET322's threshold voltage.)

In an embodiment, in normal operation, the positive supply voltage connected to SAP by PFET322is less than the boosted bitline voltage VBLHI. The swing of the signal on PSET (i.e., the gate of PFET322) may be equal to (or less than a threshold voltage of PFET322lower than) the digital logic supply voltage (e.g., VDD) to be connected to SAP. Thus, in normal non-writeback operations, the control circuitry coupled to evaluate control block320may comprise circuitry that can supply the PSET node with a signal that reaches the digital logic supply voltage VDD but does not reach VBLHI (or even reaches VBLHI minus PFET322's threshold voltage.)

Offset compensation switch block340, when activated via signals on nodes ISO and OC, disconnects the bitlines BLt and BLc from internal amplifier block310nodes SABLt and SABLc, respectively; connects BLt to SABLc; and, connects BLc to SABLt. Offset compensation switch block340includes NFETs341-544. The gates of NFETs341-542are operatively coupled together and to node ISO (a.k.a., isolate.) The source and drain nodes of NFET341are connected to BLt and SABLt, respectively. The source and drain nodes of NFET342are connected to BLc and SABLc, respectively. The source and drain nodes of NFET343are connected to BLt and SABLc, respectively. The source and drain nodes of NFET344are connected to BLc and SABLt, respectively. The swing of the signal on OC (i.e., the gates of NFETs343-344) may be equal to the digital logic supply voltage VDD. Thus, in normal operation, the control circuitry coupled to offset compensation switch block340may comprise circuitry that can supply the OC nodes with signals that at least reach VDD does not reach VBLHI.

In an embodiment, under the control of the signal on the PSETH node, PFET326switchably connects and disconnects the boosted bitline voltage VBLHI to the node SAP. PFET322, under the control of the signal on the PSET node, switchable disconnects the digital logic supply voltage from the node SAP when PFET326connects the boosted bitline voltage VBLHI to the node SAP. To disconnect the digital logic supply voltage VDD from the node SAP, the voltage on the PSET node may be boosted to VBLHI. The disconnection of the digital logic supply voltage VDD from the node SAP avoids a drive-fight between the boosted bitline voltage VBLHI and the digital logic supply voltage VDD. When PFET326connects the boosted bitline voltage VBLHI to the node SAP, an amplifier block310state selected one of the bitlines BLt and BLc are charged to the boosted bitline voltage VBLHI. In an embodiment, PFET326connects the boosted bitline voltage VBLHI to the node SAP to evaluate the voltages on the bitlines BLt and BLc. In this embodiment, PFET326may connect the boosted bitline voltage VBLHI to the node SAP without first connecting the digital logic supply voltage VDD to the node SAP.

FIGS.4A-4Care diagrams that illustrate boosted writeback operations. In general, PSET should be at VBLHI during boosted writeback operations to fully disconnect VBLHI from VDD. This can be achieved by: (1) a two-level operation where PSET is switched between VSS and VBLHI; or, (2) a three-level operation where PSET is switched between 0 and VDD during non-writeback operations, and is boosted to VBLHI during writeback operations. An example three-level operation is illustrated inFIG.4A. Example two level operations are illustrated inFIGS.4B,4C, and5.

InFIG.4A, a sense (read) operation is performed followed by a writeback operation. InFIG.4A, waveforms401and402represent the voltages on bitlines (e.g., bitlines BLt and BLc of sense amplifier200.) In a first phase (precharge operation) the waveforms401-402illustrate the bitlines are precharged to the same voltage level VBLEQ. VBLEQ may, in some embodiments, be approximately equal to VDD/2. During this first precharge phase, PSET is driven to VDD and PSETH is driven to the boosted bitline voltage VBLHI. This is to allow the bitlines to be charged to VBLEQ which, inFIG.4A, is less than both VDD and VBLHI.

The next (second) phase is signal development. Signal development is started when the equalization circuitry (e.g., sense amplifier equalize block230, and bitline equalize block240) is turned off and the wordline opens while the sense-amp is not yet switched to sense. Signal development shares the charge of the cell with the bitline and separates true and complement bitline slightly to have a signal that is then amplified in the sense phase.

In third phase (sense operation), PSET is driven to the negative reference voltage VSS, and PSETH remains at VBLHI. When PSET is driven to the negative reference voltage, the positive supply node SAP of the amplifier block (e.g., amplifier block210) of the sense amplifier is connected to VDD. This, along with the negative node being connected to VSS (not shown inFIG.4A) causes the cross-coupled inverters (e.g., amplifier block210) of the sense amplifier to evaluate the voltage difference on the bitlines. As the voltage difference is evaluated, the cross-coupled inverters feedback with each other to drive the bitlines according to the voltage difference on the bitlines. This is illustrated inFIG.4Aby waveform401charging up to VDD and waveform402discharging to VSS.

In a fourth phase (writeback operation), PSET is driven to the boosted bitline voltage VBLHI, and PSETH is driven to the negative reference voltage VSS. This causes VBLHI to be applied to the positive supply node SAP. In response, the waveform401illustrates that the bitline that was charged up to VDD further charges up to VBLHI. The waveform402illustrates that the bitline that was discharged to VSS remains at VSS. Thus, it can be seen fromFIG.4A, the waveform401illustrating the bitline is “boosted” above VDD to VBLHI. The voltage on the bitline illustrated by waveform401determines a voltage on the capacitor in a DRAM cell (e.g. cell123). Thus, the voltage on the capacitor in the DRAM cell is also “boosted.”

In a fifth phase (precharge operation), PSETH is driven to the boosted bitline voltage VBLHI and PSET is lowered to VDD. This allows the bitlines to be precharged back to the starting voltage level VBLEQ. This is illustrated inFIG.4Aby the waveforms401-402returning to VBLEQ.

InFIG.4B, a sense (read) operation is performed followed by a writeback operation. InFIG.4B, waveforms403and404represent the voltages on bitlines (e.g., bitlines BLt and BLc of sense amplifier200.) In a first phase (precharge operation) the waveforms403-404illustrate the bitlines are precharged to the same voltage level VBLEQ. VBLEQ may, in some embodiments, be approximately equal to VDD/2. During this first precharge phase, PSET and PSETH are driven to the boosted bitline voltage VBLHI. This is to allow the bitlines to be charged to VBLEQ which, inFIG.4B, is less than both VDD and VBLHI.

The next (second) phase is signal development. In a third phase (sense operation), PSET is driven to the negative reference voltage VSS and PSETH remains at VBLHI. When PSET is driven to the negative reference voltage, the positive supply node SAP of the amplifier block (e.g., amplifier block210) of the sense amplifier is connected to VDD. This, along with the negative node being connected to VSS (not shown inFIG.4B) causes the cross-coupled inverters (e.g., amplifier block210) of the sense amplifier to evaluate the voltage difference on the bitlines. As the voltage difference is evaluated, the cross-coupled inverters feedback with each other to drive the bitlines according to the voltage difference on the bitlines. This is illustrated inFIG.4Bby waveform403charging up to VDD and waveform404discharging to VSS.

In a fourth phase (writeback operation), PSET is driven to VBLHI and PSETH is driven to the negative reference voltage VSS. This causes the boosted bitline voltage VBLHI to be applied to the positive supply node SAP. In response, the waveform403illustrates that the bitline that was charged up to VDD further charges up to VBLHI. The waveform404illustrates that the bitline that was discharged to VSS remains at VSS. Thus, it can be seen fromFIG.4B, the waveform403illustrating the bitline is “boosted” above VDD to VBLHI. The voltage on the bitline illustrated by waveform403determines a voltage on the capacitor in a DRAM cell (e.g. cell123). Thus, the voltage on the capacitor in the DRAM cell is also “boosted.”

In a fifth phase (precharge operation), PSETH and PSET are driven to the boosted bitline voltage VBLHI. This allows the bitlines to be precharged back to the starting voltage level VBLEQ. This is illustrated inFIG.4Bby the waveforms403-404returning to VBLEQ.

FIG.4C, illustrates a boosted bitline voltage refresh operation. InFIG.4C, waveforms405and406represent the voltages on bitlines (e.g., bitlines BLt and BLc of sense amplifier200.) In a first phase (precharge operation) the waveforms405-406illustrate the bitlines are precharged to the same voltage level VBLEQ. VBLEQ may, in some embodiments, be approximately equal to VDD/2. During this first precharge phase, PSET and PSETH are driven to VBLHI. The waveforms405-406illustrate the bitlines are both charged to VBLEQ which, inFIG.4C, is less than both VDD and VBLHI.

The next (second) phase is signal development. In a third phase (combination sense and writeback operation), PSET remains driven to VBLHI and PSETH is driven to the negative reference voltage VSS. This causes VBLHI to be applied to the positive supply node SAP. When PSET is driven to the negative reference voltage, the positive supply node SAP of the amplifier block (e.g., amplifier block210) of the sense amplifier is connected to VBLHI. This, along with the negative node being connected to VSS (not shown inFIG.4C) causes the cross-coupled inverters (e.g., amplifier block210) of the sense amplifier to evaluate the voltage difference on the bitlines. As the voltage difference is evaluated, the cross-coupled inverters feedback with each other to drive the waveforms405-406according to the voltage difference on the bitlines. This is illustrated inFIG.4Cby waveform405charging up to VBLHI and waveform406discharging to VSS.

Thus, it can be seen fromFIG.4C, in one operation, the waveform405is “boosted” above VDD to VBLHI. The voltage on bitline illustrated by waveform405determines a voltage on the capacitor in a DRAM cell (e.g. cell123). Thus, the voltage on the capacitor in the DRAM cell is also “boosted.” In a fourth phase (precharge operation), PSETH is driven to the boosted bitline voltage VBLHI and PSET remains at VBLHI. This allows the waveforms405-406to be precharged back to the starting voltage level VBLEQ.

FIG.5is a diagram illustrating a boosted voltage write operation. InFIG.5, waveforms501and502represent the voltages on bitlines (e.g., bitlines BLt and BLc of sense amplifier200.) In a first phase (end of sense operation) the waveforms501-502illustrate the bitlines are charged to VSS and VDD, respectively. The state of the bitlines may have been determined by a previous sense or write operation that set the state of the inverters in the amplifier block (e.g., amplifier block210). At the end of this phase, PSET is being driven to VSS, PSETH is being driven to VBLHI, and column select line CSL is driven to VSS. This is to allow the bitline illustrated by waveform501to be charged up to VDD but not as high as VBLHI. This also prevents the voltages on the local data lines from overwriting the state of the inverters in the amplifier block.

In a second phase (write operation), PSET remains at VSS, and PSETH remains at VBLHI, and a column select line (CSL) is driven to VDD. When CSL is driven to VDD, the voltages on the local data lines overwrite the state of the inverters in the amplifier block. This is illustrated inFIG.5by waveform501charging up to VDD and waveform502discharging to VSS.

In a third phase (writeback operation), PSET is driven to VBLHI, PSETH is driven to the negative reference voltage VSS, and CSL is driven to VSS. This causes VBLHI to be applied to the positive supply node SAP. In response, the waveform501that was charged up to VDD further charges up to VBLHI. The waveform502that was discharged to VSS remains at VSS. Thus, it can be seen fromFIG.5, the waveform501is “boosted” above VDD to VBLHI. The voltage on waveform501determines a voltage on the capacitor in a DRAM cell (e.g. cell123). Thus, the voltage on the capacitor in the DRAM cell is also “boosted.”

In a fourth phase (precharge operation), PSETH is driven to the boosted bitline voltage VBLHI, PSET remains at VBLHI, and CSL remains at VSS. This allows the bitlines illustrated by waveforms501-502to be precharged back to the starting voltage level VBLEQ.

FIG.6is a flowchart illustrating a boosted writeback method. One or more steps illustrated inFIG.6may be performed by, for example, memory system100, sense amplifier200, sense amplifier300, and/or their components. Using a digital logic supply voltage level to power cross-coupled inverters, a digital value is sensed from a voltage differential between two bitlines of a dynamic memory array (602). For example, using the digital logic supply voltage VDD to power the cross-coupled inverters of amplifier block210, sense amplifier200may use a voltage differential between the true (BLt) and complement (BLc) bitlines connected to sense amplifier200to sense a digital value corresponding to that voltage differential.

The digital value is written to the dynamic memory array using a bitline voltage that is greater than the digital logic supply voltage level (604). For example, boosted bitline control block of sense amplifier200may couple a boosted bitline voltage VBLHI that is greater than VDD to the positive supply node SAP of amplifier block210. This allows a one of the cross-coupled inverters of amplifier block210to drive the boosted bitline voltage VBLHI into the dynamic memory array (e.g., subarray128) where the boosted bitline voltage VBLHI will charge the capacitor of a dynamic memory array cell (e.g., cell123.)

FIG.7is a flowchart illustrating a boosted write method. One or more steps illustrated inFIG.7may be performed by, for example, memory system100, sense amplifier200, sense amplifier300, and/or their components. A state of a pair of cross-coupled inverters of a sense amplifier of a dynamic memory array is set using a digital logic supply voltage level to power the cross-coupled inverters (702). For example, during a write operation which sets their state based on voltages on local data lines LDQt and LDQc, the cross-coupled inverters of amplifier block210of sense amplifier200may be powered by a VDD level voltage from evaluate control block320.

The state of the pair of cross-coupled inverters of the sense amplifier is written to the dynamic memory array using a bitline voltage that is greater than the digital logic supply voltage level (704). For example, based on the state of the cross-coupled inverters, sense amplifier200may drive a boosted bitline voltage VBLHI that is greater than VDD to a one of the true (BLt) and complement (BLc) bitlines corresponding to the state of the cross-coupled inverters. This allows sense amplifier200to drive the boosted bitline voltage VBLHI into the dynamic memory array (e.g., subarray128) where the boosted bitline voltage VBLHI will charge the capacitor of a dynamic memory array cell (e.g., cell123.)

FIG.8is a method of operating a memory device. One or more steps illustrated inFIG.8may be performed by, for example, memory system100and/or its components. A first command is communicated to a memory device to operate a plurality of sense amplifier circuits that are part of a dynamic memory array of the memory device to use a digital logic supply voltage level during sense operations and column operations (802). For example, controller180may communicate, via interface185, a command (and/or sets a register value) that causes memory device110to configure sense amplifiers130to sense the state of memory bit cells (e.g., cell123) using the digital logic supply voltage level (e.g., VDD) and/or maximum signal swing level (with respect to the same negative supply/reference/substrate voltage as the bitline voltage is referenced to) that is used by a majority of the digital logic on DRAM memory device110.

During writeback operations, the memory device is controlled to use a bitline voltage that is greater than the digital logic supply voltage (804). For example, controller180may communicate, via interface185, a command (and/or sets a register value) that causes memory device110to configure sense amplifiers130to writeback the state of memory bit cells (e.g., cell123) using boosted bitline supply (e.g. VBLHI) and/or maximum signal swing level (with respect to the same negative supply/reference/substrate voltage as the digital logic supply voltage level is referenced to) that is greater than the digital logic supply voltage level used by a majority of the digital logic on DRAM memory device110.

FIG.9is a method of adjusting a writeback voltage. One or more steps illustrated inFIG.9may be performed by, for example, memory system100and/or its components. A first command is communicated to a memory device to operate a plurality of sense amplifier circuits that are part of a dynamic memory array of the memory device to use a digital logic supply voltage level during sense operations and column operations (902). For example, controller180may communicate, via interface185, a register value (and/or a command) that causes memory device110to configure sense amplifiers130to sense the state of memory bit cells (e.g., cell123) using the digital logic supply voltage level (e.g., VDD) and/or maximum signal swing level (with respect to the same negative supply/reference/substrate voltage as the bitline voltage is referenced to) that is used by a majority of the digital logic on DRAM memory device110.

A second indicator is communicated to the memory device to operate the plurality of sense amplifier circuits at a first bitline voltage during writeback operations (904). For example, controller180may communicate, via interface185, a register value (and/or a command) that causes memory device110to configure sense amplifiers130to writeback the state of memory bit cells (e.g., cell123) using boosted bitline supply (e.g. VBLHI) and/or maximum signal swing level.

A third indicator is communicated to the memory device to operate the plurality of sense amplifier circuits at a second bitline voltage during writeback operations, where the second bitline voltage is not equal to the first bitline voltage (904). For example, controller180may communicate, via interface185, a register value (and/or a command) that causes memory device110to configure sense amplifiers130to writeback the state of memory bit cells (e.g., cell123) using different boosted bitline supply and/or maximum signal swing level. In another example, controller180may communicate, via interface185, a register value (and/or a command) that causes memory device110to change the voltage level of VBLHI.

The methods, systems and devices described above may be implemented in computer systems, or stored by computer systems. The methods described above may also be stored on a non-transitory computer readable medium. Devices, circuits, and systems described herein may be implemented using computer-aided design tools available in the art, and embodied by computer-readable files containing software descriptions of such circuits. This includes, but is not limited to one or more elements of memory system100, sense amplifier200, sense amplifier300, and their components. These software descriptions may be: behavioral, register transfer, logic component, transistor, and layout geometry-level descriptions. Moreover, the software descriptions may be stored on storage media or communicated by carrier waves.

Data formats in which such descriptions may be implemented include, but are not limited to: formats supporting behavioral languages like C, formats supporting register transfer level (RTL) languages like Verilog and VHDL, formats supporting geometry description languages (such as GDSII, GDSIII, GDSIV, CIF, and MEBES), and other suitable formats and languages. Moreover, data transfers of such files on machine-readable media may be done electronically over the diverse media on the Internet or, for example, via email. Note that physical files may be implemented on machine-readable media such as: 4 mm magnetic tape, 8 mm magnetic tape, 3½ inch floppy media, CDs, DVDs, and so on.

FIG.10is a block diagram illustrating one embodiment of a processing system1000for including, processing, or generating, a representation of a circuit component1020. Processing system1000includes one or more processors1002, a memory1004, and one or more communications devices1006. Processors1002, memory1004, and communications devices1006communicate using any suitable type, number, and/or configuration of wired and/or wireless connections1008.

Processors1002execute instructions of one or more processes1012stored in a memory1004to process and/or generate circuit component1020responsive to user inputs1014and parameters1016. Processes1012may be any suitable electronic design automation (EDA) tool or portion thereof used to design, simulate, analyze, and/or verify electronic circuitry and/or generate photomasks for electronic circuitry. Representation1020includes data that describes all or portions of memory system100, sense amplifier200, sense amplifier300, and their components, as shown in the Figures.

Representation1020may include one or more of behavioral, register transfer, logic component, transistor, and layout geometry-level descriptions. Moreover, representation1020may be stored on storage media or communicated by carrier waves.

Data formats in which representation1020may be implemented include, but are not limited to: formats supporting behavioral languages like C, formats supporting register transfer level (RTL) languages like Verilog and VHDL, formats supporting geometry description languages (such as GDSII, GDSIII, GDSIV, CIF, and MEBES), and other suitable formats and languages. Moreover, data transfers of such files on machine-readable media may be done electronically over the diverse media on the Internet or, for example, via email

User inputs1014may comprise input parameters from a keyboard, mouse, voice recognition interface, microphone and speakers, graphical display, touch screen, or other type of user interface device. This user interface may be distributed among multiple interface devices. Parameters1016may include specifications and/or characteristics that are input to help define representation1020. For example, parameters1016may include information that defines device types (e.g., NFET, PFET, etc.), topology (e.g., block diagrams, circuit descriptions, schematics, etc.), and/or device descriptions (e.g., device properties, device dimensions, power supply voltages, simulation temperatures, simulation models, etc.).

Memory1004includes any suitable type, number, and/or configuration of non-transitory computer-readable storage media that stores processes1012, user inputs1014, parameters1016, and circuit component1020.

Communications devices1006include any suitable type, number, and/or configuration of wired and/or wireless devices that transmit information from processing system1000to another processing or storage system (not shown) and/or receive information from another processing or storage system (not shown). For example, communications devices1006may transmit circuit component1020to another system. Communications devices1006may receive processes1012, user inputs1014, parameters1016, and/or circuit component1020and cause processes1012, user inputs1014, parameters1016, and/or circuit component1020to be stored in memory1004.

Implementations discussed herein include, but are not limited to, the following examples:

Example 1: A dynamic random access memory (DRAM) device, comprising: digital logic circuitry to at least process column addresses and row addresses to retrieve data stored in a dynamic memory array, the digital logic circuitry to operate using a first digital logic supply voltage level; and, sense amplifier circuits that are part of the dynamic memory array to operate using the first digital logic supply voltage level during sense operations and column operations and to operate, during writeback operations, using a boosted bitline voltage that is greater than the first digital logic supply voltage level.

Example 2: The DRAM device of example 1, wherein the digital logic circuitry is implemented using a high-k metal gate process.

Example 3: The DRAM device of example 1, wherein the sense amplifier circuits include a pair of cross-coupled inverters in a bi-stable flip-flop configuration coupled to respective bitlines of the dynamic memory array, the pair of cross-coupled inverters each having a negative supply node and a positive supply node.

Example 4: The DRAM device of example 3, wherein the boosted bitline voltage is selectively coupled to the positive supply node of the pair of cross-coupled inverters during writeback operations.

Example 5: The DRAM device of example 4, wherein the first digital logic supply voltage level is selectively coupled to the positive supply node of the pair of cross-coupled inverters during sense operations and column operations.

Example 6: The DRAM device of example 4, wherein the boosted bitline voltage is selectively coupled to the positive supply node of the pair of cross-coupled inverters during refresh operations.

Example 7: The DRAM device of example 4, wherein the boosted bitline voltage is selectively coupled to the positive supply node of the pair of cross-coupled inverters using a p-channel field effect transistor (PFET) having a PFET gate node to be controlled using logic that applies voltages to the PFET gate node that at least reach the boosted bitline voltage minus a threshold voltage of the PFET.

Example 8: A dynamic random access memory (DRAM) device, comprising: sense amplifier circuits that are part of a dynamic memory array to operate using a first digital logic supply voltage level during a first plurality of sense operations and a first plurality of column operations and to operate, during a first plurality of writeback operations that occur after respective ones of the first plurality of sense operations to writeback data sensed by the respective ones of the first plurality of sense operations, using a first bitline voltage that is greater than the first digital logic supply voltage level; and, digital logic to at least process received commands, column addresses, and row addresses to retrieve data stored in the dynamic memory array, the digital logic to operate using the first digital logic supply voltage level.

Example 9: The DRAM of example 8, wherein the first bitline voltage is based on a first received command.

Example 10: The DRAM of example 9, wherein the sense amplifier circuits are to, based on a second received command, and during a writeback operation that occurs after a sense operation to writeback data sensed by the sense operation, operate using a second bitline voltage that is equal to the first digital logic supply voltage level.

Example 11: The DRAM of example 9, wherein the sense amplifier circuits are to, based on a second received command, and during a writeback operation that occurs after a sense operation to writeback data sensed by the sense operation, operate using a second bitline voltage that is not equal to the first bitline voltage and is greater than or equal to the first digital logic supply voltage level.

Example 12: The DRAM of example 10, wherein the second bitline voltage is based on a temperature of the DRAM.

Example 13: The DRAM of example 8, wherein the sense amplifier circuits are to, based on a first received command, precharge respective bitlines of the dynamic memory array to a precharge voltage that is derived from the first digital logic supply voltage level.

Example 14: The DRAM of example 8, wherein the sense amplifier circuits are to, based on a first received command, perform refresh operations using a second bitline voltage that is equal to the first digital logic supply voltage level.

Example 15: A memory controller, comprising: a command interface to communicate a first indicator and a second indicator to a memory device, based at least on the first indicator, the memory device to operate a plurality of sense amplifier circuits that are part of a dynamic memory array of the memory device using a first digital logic supply voltage level during a first sense operation and a first column operation and to operate, during a first writeback operation that occurs after the first sense operation to writeback data sensed by the first sense operation, using a first bitline voltage that is greater than the first digital logic supply voltage level, the memory device to, based at least on the second indicator, to operate, during a second writeback operation that occurs after a second sense operation to writeback data sensed by the second sense operation, using a second bitline voltage that is equal to the first digital logic supply voltage level; and, a data interface to receive data sensed by the respective ones of the first plurality of sense operations.

Example 16: The memory controller of example 15, wherein the first indicator is based on a command.

Example 17: The memory controller of example 15, wherein the command interface is to communicate a third indicator to the memory device, the memory device to, based on the third indicator, and during a third writeback operation that occurs after a third sense operation, operate the plurality of sense amplifier circuits using a third bitline voltage that is not equal to the first bitline voltage and is greater than or equal to the first digital logic supply voltage level to writeback data sensed by the third sense operation.

Example 18: The memory controller of example 15, wherein the third indicator is based on a command.

Example 19: The memory controller of example 15, wherein the first bitline voltage is based on a temperature of the memory device.

Example 20: The memory controller of example 17, wherein the third bitline voltage is based on a temperature of the memory device.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.