STATIC RANDOM ACCESS MEMORY

• US 20150049540A1
• Filed: 08/15/2013
• Published: 02/19/2015
• Est. Priority Date: 08/15/2013
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: SON, Jin Seung, KENKARE, Prashant Umakant
• Granted Patent: US 9,460,778 B2
• Time in Patent Office: Days
• US Class Current: 365/154
• CPC Class Codes: G11C 11/419 Read-write [R-W] circuits
• CPC Class Codes: G11C 7/12 Bit line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, equalising circuits, for bit lines

Abstract

A static random access memory includes a memory cell array, a control logic configured to generate a first write clock signal and a second write clock signal each of which having a pulse width shorter than a pulse width of a clock signal in response to the clock signal, a row decoder configured to select a word line in response to the second write clock signal during a write operation, a column selector configured to select a bit line and an inverted bit line, a sense amplifier configured to sense states of the selected bit line and the selected inverted bit line during a read operation and a write driver configured to bias the selected bit line and the selected inverted bit line in response to the first write clock signal during the write operation.

Claims

1. A static random access memory comprising:

a memory cell array comprising a plurality of memory cells;

a control logic configured to generate a first write clock signal and a second write clock signal in response to a received clock signal, each of the first and second write clock signals having a pulse width shorter than a pulse width of the clock signal;

a row decoder connected to the plurality of memory cells through a plurality of word lines and configured to select a word line in response to the second write clock signal during a write operation;

a column selector connected to the plurality of memory cells through a plurality of bit lines and a plurality of inverted bit lines and configured to select a bit line and an inverted bit line;

a sense amplifier connected to the bit line and the inverted bit line selected by the column selector and configured to sense states of the selected bit line and the selected inverted bit line during a read operation; and

a write driver connected to the bit line and the inverted bit line selected by the column selector and configured to bias the selected bit line and the selected inverted bit line in response to the first write clock signal during the write operation.

2. The static random access memory of claim 1, wherein one of a rising edge and a falling edge of one or more of the first and second write clock signals are synchronized with one edge of the clock signal.

3. The static random access memory of claim 1, wherein the control logic comprises a write time register configured to store information about a write time and a word line turn off time, and

wherein a rising edge of each of the first and second write clock signals are synchronized with a rising edge of the clock signal and a falling edge of the first write clock signal occurs after the write time elapses from the rising edge of the first write clock signal and a falling edge of the second write clock signal occurs after a time duration relative to the rising edge of the second write clock signal, where the time duration is defined as a sum of the write time and the word line turn off time.

4. The static random access memory of claim 1, wherein the row decoder is configured to apply a turn-on voltage to the selected word line during an active state of the second write clock signal.

5. The static random access memory of claim 1, wherein, during the write operation, the write driver is configured to discharge one of the selected bit line and the selected inverted bit line to a ground voltage.

6. The static random access memory of claim 5, wherein, during the write operation, the write driver is configured to boost the bit line or inverted bit line discharged to the ground voltage to a negative voltage in response to transition of the first write clock signal to an inactive state.

7. The static random access memory of claim 1, wherein the write driver comprises:

a first discharge circuit configured to selectively discharge the bit line selected by the column selector to a ground voltage in response to write data and the first write clock signal;

a second discharge circuit configured to selectively discharge the inverted bit line selected by the column selector to the ground voltage in response to inverted write data and the first write clock signal; and

a boost circuit configured to boost one of the selected bit line and the selected inverted bit line to a negative voltage in response to the first write clock signal.

8. The static random access memory of claim 7, wherein the write driver further comprises a first inverter configured to invert the first write clock signal to output the inverted write clock signal, and

wherein the first discharge circuit, the second discharge circuit, and the boost circuit operate in response to the inverted first write clock signal.

9. The static random access memory of claim 8, wherein the first discharge circuit comprises:

a first logic configured to perform a logical operation on the write data and the inverted first write clock signal to output a logical operation result; and

a first transistor configured to discharge the bit line selected by the column selector to the ground voltage in response to the logical operation result of the first logic.

10. The static random access memory of claim 8, wherein the second discharge circuit comprises:

a second logic configured to perform a logical operation on the inverted write data and the inverted first write clock signal to output a logical operation result; and

a second transistor configured to discharge the inverted bit line selected by the column selector to the ground voltage in response to the logical operation result of the second logic.

11. The static random access memory of claim 8, wherein the boost circuit comprises:

a second inverter configured to invert the inverted write clock signal to output a boost signal;

a third inverter configured to invert a voltage of the bit line selected by the column selector to output a first inverted voltage;

a third transistor configured to electrically connect the bit line selected by the column selector and a boost node according to the first inverted voltage;

a fourth inverter configured to invert a voltage of the inverted bit line selected by the column selector to output a second inverted voltage;

a fourth transistor configured to electrically connect the inverted bit line selected by the column selector and the boost node according to the second inverted voltage; and

a capacitor connected between an output node of the second inverter and the boost node.

12. A static random access memory comprising:

a memory cell array including a plurality of memory cells;

a row decoder connected to the plurality of memory cells through a plurality of word lines and configured to select a word line during a write operation;

a column selector connected to the plurality of memory cells through a plurality of bit lines and a plurality of inverted bit lines and configured to select a bit line and an inverted bit line;

a sense amplifier connected to the bit line and the inverted bit line selected by the column selector and configured to sense states of the selected bit line and the selected inverted bit line during a read operation; and

a write driver connected to the bit line and the inverted bit line selected by the column selector and configured to boost one of the selected bit line and the selected inverted bit line to a negative voltage during the write operation.

13. The static random access memory of claim 12, wherein the write driver is configured to discharge the one of the selected bit line and the selected inverted bit line during the write operation, and when a predetermined write time passes after the one of the selected bit line and the selected inverted bit line begins to be discharged, the write driver is configured to boost the discharged bit line or inverted bit line to a negative voltage.

14. The static random access memory of claim 12, further comprising a control logic configured to control the row decoder and the write driver in response to a clock signal externally provided,

wherein the control logic controls the write driver to discharge one of the selected bit line and the selected inverted bit line in response to a first edge of the clock signal and perform the boost after the write time passes from the first edge of the clock signal.

15. The static random access memory of claim 14, wherein the control logic controls the row decoder such that a turn-on voltage is applied to the selected word line in response to the first edge of the clock signal and the turn-on voltage ceases to be applied to the selected word line after the a time duration passes from the first edge of the clock signal, where the time duration is greater than the write time and shorter than a pulse width of the clock signal.

16. A method of performing a write operation of a memory device comprising a plurality of memory cells, the method comprising:

selecting a word line from among a plurality of word lines associated with the plurality of memory cells;

applying a turn-on voltage to the selected word line in response to a clock signal;

selectively discharging one of a bit line or an inverted bit line in response to write data and the clock signal during a predetermined write time; and

boosting one of the discharged bit line or inverted bit line to a negative voltage in response to an elapse of the predetermined write time.

17. The method of claim 16, wherein the predetermined write time is shorter than a pulse width of the clock signal.

18. The method of claim 16, further comprising:

generating a write clock signal in response to the clock signal, the write clock signal having a pulse width corresponding to the predetermined write time,

wherein the selectively discharging is performed in response to the write clock signal.

19. The method of claim 18, wherein one of a rising edge and a falling edge of the write clock signal is synchronized with one edge of the clock signal.

20. The method of claim 16, further comprising:

applying a turn-off voltage to the selected word line after a time duration exceeding the predetermined write time elapses such that the time duration is shorter than a pulse width of the clock signal and longer than the predetermined write time.