Dynamic random access memory system including single-ended sense amplifiers and methods for operating same

1 . A dynamic random access memory (DRAM) system comprising:

a first array of DRAM cells arranged in a plurality of rows and columns, wherein each of the columns of DRAM cells is coupled to a corresponding bit line; and

a plurality of single-ended sense amplifiers, each coupled to a corresponding bit line of the first array of DRAM cells, wherein each of the single-ended sense amplifiers comprises:

a kick capacitor coupled to the corresponding bit line;

a latch circuit having a first internal node for storing a data value; and

an isolation transistor coupling the corresponding bit line to the first internal node of the latch circuit, wherein the corresponding bit line is the only bit line of the first array of DRAM cells coupled to the latch circuit.

2 . The DRAM system of claim 1 , wherein the latch circuit further comprises:

a first p-channel transistor having a source coupled to a first control node, a gate coupled to the first internal node and a drain coupled to a second internal node;

a first n-channel transistor having a source coupled to a second control node, a gate coupled to the first internal node and a drain coupled to the second internal node;

a second p-channel transistor having a source coupled to the first control node, a gate coupled to the second internal node and a drain coupled to the first internal node; and

a second n-channel transistor having a source coupled to the second control node, a gate coupled to the second internal node and a drain coupled to the first internal node.

3 . The DRAM system of claim 2 , further comprising:

a first pre-charge transistor for selectively coupling the first internal node to a ground voltage supply; and

a second pre-charge transistor for selectively coupling the second internal node to the ground voltage supply.

4 . The DRAM system of claim 2 , further comprising:

means for varying a voltage applied to the first control node between ground and a positive supply voltage; and

means for varying a voltage applied to the second control node between ground and a negative supply voltage.

5 . The DRAM system of claim 2 , wherein each of the single-ended sense amplifiers further comprises: a p-channel transistor having a gate coupled to the second internal node, a drain coupled to the corresponding bit line, and a source coupled to receive a bit line refresh control signal.

6 . The DRAM system of claim 2 , wherein the first p-channel transistor, the first n-channel transistor, the second p-channel transistor and the second n-channel transistor have matched threshold voltages.

7 . The DRAM system of claim 2 , wherein the isolation transistor has a thick gate oxide layer relative to the first p-channel transistor, the first n-channel transistor, the second p-channel transistor and the second n-channel transistor.

8 . The DRAM system of claim 1 , further comprising means for varying a voltage applied to the kick capacitor during a read access.

9 . The DRAM system of claim 1 , wherein the kick capacitor is coupled to receive a kick control signal that causes a voltage on the corresponding bit line to be kicked lower during a read access.

10 . The DRAM system of claim 9 , wherein each of the single-ended sense amplifiers further comprises a second isolation transistor coupling the corresponding bit line of the second array of DRAM cells to the first internal node of the latch circuit, wherein the corresponding bit line of the second array of DRAM cells is the only bit line of the second array of DRAM cells coupled to the latch circuit.

11 . The DRAM system of claim 9 , further comprising a second array of DRAM cells arranged in a plurality of rows and columns, wherein each of the columns of DRAM cells in the second array of DRAM cells is coupled to a corresponding bit line, wherein each of the plurality of single-ended sense amplifiers is further coupled to a corresponding bit line of the second array of DRAM cells.

12 . The DRAM system of claim 1 , wherein each of the single-ended sense amplifiers further comprises an output select transistor that selectively couples the first internal node to a global bit line.

13 . The DRAM system of claim 1 , wherein the first array of DRAM cells includes only 512 rows of DRAM cells.

14 . A method of operating a dynamic random access memory (DRAM) system comprising:

pre-charging a bit line coupled to a DRAM cell to ground;

pre-charging first and second internal nodes of a sense amplifier latch to ground;

driving first and second supply voltage terminals of the sense amplifier latch to ground;

activating a word line coupled to the DRAM cell, thereby causing the DRAM cell to develop a read voltage on the bit line;

activating a kick capacitor to drive down the read voltage developed on the bit line; then

coupling the bit line to the first internal node of the sense amplifier latch, thereby applying the read voltage developed on the bit line to the first internal node of the sense amplifier latch; then

isolating the bit line from the first internal node of the sense amplifier latch;

driving the first supply voltage terminal of the sense amplifier latch to a first supply voltage above ground, and driving the second supply voltage terminal of the sense amplifier latch to a second supply voltage; and then

coupling the bit line to the first internal node of the sense amplifier latch.

15 . The method of claim 14 , wherein activating the word line comprises, initially applying a positive voltage to the word line, and then boosting the positive voltage.

16 . The method of claim 14 , further comprising isolating the bit line from the first internal node of the sense amplifier latch when activating the word line and activating the kick capacitor.

17 . The method of claim 14 , further comprising allowing the first internal node to float at ground before coupling the bit line to the first internal node of the sense amplifier latch.

18 . The method of claim 14 , wherein activating the word line comprises driving a word line voltage on the word line from a negative voltage to a positive voltage.

19 . The method of claim 14 , wherein activating the word line and activating the kick capacitor develops a negative read voltage on the bit line when the DRAM cell stores a data value having a first logic state, and develops a positive read voltage on the bit line when the DRAM cell stores a data value having a second logic state.

20 . The method of claim 19 , wherein the sense amplifier latch compares the read voltage applied to the first internal node with a voltage on the second internal node of the sense amplifier latch, which has been pre-charged to ground.

21 . The method of claim 20 , wherein the second internal node initially floats at ground when the sense amplifier compares the read voltage applied to the first internal node with the voltage on the second internal node of the sense amplifier latch.

22 . The method of claim 19 , further comprising:

pulling the second internal node from ground up to the first supply voltage, and pulling the first internal node from the negative read voltage down to the second supply voltage if the DRAM cell stores a data value having the first logic state; and

pulling the second internal node from ground down to the second supply voltage, and pulling the first internal node up from the positive read voltage to the first supply voltage if the DRAM cell stores a data value having the second logic state.

23 . The method of claim 22 , further comprising pulling the bit line up to a boosted positive voltage greater than the first supply voltage in response to pulling the second internal node to the second supply voltage, and isolating the bit line from the boosted positive voltage in response to pulling the second internal node to the first supply voltage.

24 . The method of claim 14 , wherein coupling the bit line to the first internal node and isolating the bit line from the first internal node is implemented by an isolation transistor coupling the bit line and the first internal node.

25 . The method of claim 24 , wherein the isolation transistor is enabled to couple the bit line to the first internal node by applying a boosted positive voltage, greater than the first supply voltage, to a gate of the isolation transistor.

26 . A dynamic random access memory (DRAM) system comprising:

a first integrated circuit chip including a plurality of processors;

a second integrated circuit chip including a first plurality of independent DRAM arrays, wherein each of the first plurality of independent DRAM arrays is connected to a corresponding one of the plurality of processors on the first integrated circuit chip; and

refresh control circuitry located on the first integrated circuit chip, wherein the refresh control circuitry initiates refresh operations to the first plurality of DRAM arrays on the second integrated circuit chip.

27 . The DRAM system of claim 26 , wherein the first integrated circuit chip comprises an interconnect structure that couples each of the plurality of processors.

28 . The DRAM system of claim 26 , further comprising a plurality of through silicon via (TSV) structures connecting the first and second integrated circuit chips.

29 . The DRAM system of claim 26 , further comprising a third integrated circuit chip including a plurality of DRAM arrays, wherein each of the plurality of DRAM arrays of the third integrated circuit chip is connected to a corresponding one of the plurality of processors on the first integrated circuit chip.

30 . The DRAM system of claim 29 , further comprising:

a first set of through silicon via (TSV) structures connecting the first and second integrated circuit chips; and

a second set of TSV structures connecting the first and third integrated circuit chips, wherein the second set of TSV structures extend through the first integrated circuit chip.

31 . The DRAM system of claim 26 , further comprising a power management integrated circuit coupled to the first integrated circuit chip and the second integrated circuit chip, wherein the power management integrated circuit provides a first plurality of supply voltages to the first integrated circuit chip and the second integrated circuit chip, and a second plurality of supply voltages only to the second integrated circuit chip.

32 . A dynamic random access memory (DRAM) system comprising:

a first integrated circuit chip including a plurality of processors;

a second integrated circuit chip including a first plurality of independent DRAM sectors, wherein each of the first plurality of independent DRAM sectors is connected to a corresponding one of the plurality of processors on the first integrated circuit chip via a first plurality of through silicon via (TSV) interconnect structures; and

a third integrated circuit chip including a second plurality of independent DRAM sectors, wherein each of the second plurality of independent DRAM sectors is connected to a corresponding one of the plurality of processors on the first integrated circuit chip via a second plurality of TSV interconnect structures, wherein the second plurality of TSV interconnect structures extend through the first integrated circuit chip.

33 . A dynamic random access memory (DRAM) unit cell located on an integrated circuit chip, wherein the DRAM unit cell comprises:

a plurality of through silicon vias (TSVs) that extend through the integrated circuit chip;

a first plurality of DRAM banks that are aligned along a first axis; and

a second plurality of DRAM banks that are aligned along the first axis, wherein the plurality of TSVs are located between the first and second plurality of DRAM banks along the first axis, wherein the plurality of TSVs transmit address and control signals for accessing the first and second plurality of DRAM banks, and wherein the plurality of TSVs transmit read and write data for the first and second plurality of DRAM banks, wherein each of the first and second plurality of DRAM banks includes:

a plurality of strips, wherein each strip includes:

a plurality of corresponding rows of DRAM bit cells of the DRAM bank;

a first primary sense amplifier circuit located adjacent to a first one of the plurality of corresponding rows of DRAM bit cells, wherein a first subset of the DRAM bit cells is coupled to the first primary sense amplifier circuit; and

a second primary sense amplifier circuit located adjacent to a last one of the plurality of corresponding rows of DRAM bit cells, wherein a second subset of the DRAM bit cells are coupled to the second primary sense amplifier circuit.

34 . A dynamic random access memory (DRAM) unit cell comprising:

a first memory bank having:

a plurality of rows and columns of DRAM cells, wherein the plurality of rows of the first memory bank are divided into N DRAM strips, wherein N is an integer greater than one, and wherein each of the N DRAM strips of the first memory bank includes a plurality of consecutive rows of the DRAM cells of the first memory bank;

a plurality of N+1 primary sense amplifier circuits, wherein each of the N DRAM strips of the first memory bank is coupled to a corresponding pair of the primary sense amplifier circuits of the first memory bank;

a second memory bank having:

a plurality of rows and columns of DRAM cells, wherein the plurality of rows of the second memory bank are divided into N DRAM strips, and wherein each of the N DRAM strips of the second memory bank includes a plurality of consecutive rows of the DRAM cells of the second memory bank;

a plurality of N+1 primary sense amplifier circuits, wherein each of the N DRAM strips of the second memory bank is coupled to a corresponding pair of the primary sense amplifier circuits of the second memory bank; and

a secondary sense amplifier circuit located between the first and second memory banks, wherein the secondary sense amplifier circuit is coupled to each of the primary sense amplifier circuits of the first and second memory banks.

35 . The DRAM unit cell of claim 34 , wherein a first half of the columns of DRAM cells in one of the N DRAM strips of the first memory bank is coupled to a first one of the primary sense amplifier circuits of the first memory bank, and a second half of the columns of the one of the N DRAM strips of the first memory bank is coupled to a second one of the primary sense amplifier circuits of the first memory bank.

36 . The DRAM unit cell of claim 34 , wherein each of the N DRAM strips of the first memory bank comprises:

a plurality of main word lines; and

a plurality of virtual sub-word lines, wherein each of the main word lines is coupled to a corresponding plurality of the virtual sub-word lines, and wherein each of the virtual sub-word lines is coupled to a row of the DRAM cells of the first memory bank.

37 . The DRAM unit cell of claim 36 , wherein each of the virtual sub-word lines comprises a plurality of independent sub-word line segments, wherein each sub-word line segment is coupled to a plurality of consecutive DRAM cells in a row of the DRAM cells of the first memory bank.

38 . The DRAM unit cell of claim 37 , further comprising a plurality of sub-word line drivers, wherein each of the sub-word line drivers is coupled to a corresponding one of the sub-word line segments.

39 . The DRAM unit cell of claim 38 , wherein each of the sub-word line drivers is coupled to receive a main word line signal from a corresponding one of the plurality of main word lines, and a sub-word line segment select signal for selecting the sub-word line segment coupled to the sub-word line driver.

40 . The DRAM unit cell of claim 37 , further comprising an instruction for specifying an access to the first memory bank of the DRAM unit cell comprising:

a bank address for selecting the first memory bank;

a main word line address for selecting one of the plurality of main word lines of the first memory bank; and

a sub-word line segment address for selecting one of the sub-word line segments of the plurality of virtual sub-word lines coupled to the selected one of the plurality of main word lines.

41 . The DRAM unit cell of claim 40 , wherein the instruction further comprises:

a column select address for selecting a word within the selected one of the sub-word line segments;

a burst value for indicating a burst length of the access; and

a read/write value for indicating whether the access is a read access or a write access.

42 . A dynamic random access memory (DRAM) system comprising:

a first set of DRAM cells arranged in a plurality of rows and four columns, wherein each of the four columns of DRAM cells in the first set of DRAM cells is coupled to a corresponding bit line of a first group of four bit lines;

a second set of DRAM cells arranged in a plurality of rows and four columns, wherein each of the four columns of DRAM cells in the second set of DRAM cells is coupled to a corresponding bit line of a second group of four bit lines; and

a first single-ended sense amplifier pair located between the first and second sets of DRAM cells, wherein the first single-ended sense amplifier pair comprises:

a first single-ended sense amplifier;

a second single-ended sense amplifier;

a first transistor for selectively coupling and decoupling the first single-ended sense amplifier to a first bit line of the first group of bit lines;

a second transistor for selectively coupling and decoupling the first single-ended sense amplifier to a first bit line of the second group of bit lines, wherein the first and second transistors are controlled such that the first single-ended sense amplifier is coupled to, at most, one bit line at a time;

a third transistor for selectively coupling and decoupling the second single-ended sense amplifier to a second bit line of the first group of bit lines;

a fourth transistor for selectively coupling and decoupling the second single-ended sense amplifier to a second bit line of the second group of bit lines, wherein the third and fourth transistors are controlled such that the second single-ended sense amplifier is coupled to, at most, one bit line at a time.

43 . The DRAM system of claim 42 , wherein the first single-ended sense amplifier pair has a width less than or equal to a width corresponding to four times a pitch between adjacent ones of the bit lines.

44 . The DRAM system of claim 43 , further comprising:

a second single-ended sense amplifier pair located adjacent to the first set of DRAM cells, wherein the second single-ended sense amplifier pair comprises:

a third single-ended sense amplifier;

a fourth single-ended sense amplifier;

a fifth transistor for selectively coupling and decoupling the third single-ended sense amplifier to a third bit line of the first group of bit lines; and

a sixth transistor for selectively coupling and decoupling the fourth single-ended sense amplifier to a fourth bit line of the first group of bit lines.

45 . The DRAM system of claim 44 , further comprising a global bit line coupled to the first and second single-ended sense amplifiers of the first single-ended sense amplifier pair and the third and fourth single-ended sense amplifiers of the second single-ended sense amplifier pair.

46 . The DRAM system of claim 44 , further comprising:

a third single-ended sense amplifier pair located adjacent to the second set of DRAM cells, wherein the third single-ended sense amplifier pair comprises:

a fifth single-ended sense amplifier;

a sixth single-ended sense amplifier;

a seventh transistor for selectively coupling and decoupling the fifth single-ended sense amplifier to a third bit line of the second group of bit lines; and

an eighth transistor for selectively coupling and decoupling the sixth single-ended sense amplifier to a fourth bit line of the second group of bit lines.

47 . The DRAM system of claim 46 , further comprising a global bit line coupled to the first and second single-ended sense amplifiers of the first single-ended sense amplifier pair, the third and fourth single-ended sense amplifiers of the second single-ended sense amplifier pair and the fifth and sixth single-ended sense amplifiers of the third single-ended sense amplifier pair.

48 . The DRAM system of claim 44 , further comprising a global bit line coupled to the first and second single-ended sense amplifiers of the first single-ended sense amplifier pair.