Non-volatile dynamic random access memory (NVDRAM)

• US 9,401,198 B1
• Filed: 06/30/2015
• Issued: 07/26/2016
• Est. Priority Date: 06/30/2015
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Roy, Anirban
• Primary Examiner(s): Auduong, Gene
• Application Number:
  US14/788,285
• Time in Patent Office: 392 Days
• Field of Search: 365/63, 365/72, 365/148, 365/158, 365/185.05, 365/185.18, 365/185.15, 365/185.24
• US Class Current: 1/1
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/405 with three charge-transfer gates, e.g. MOS transistors, per cell
• CPC Class Codes: G11C 11/4087 Address decoders, e.g. bit - or word line decoders; Multiple line decoders
• CPC Class Codes: G11C 11/4096 Input/output [I/O] data management or control circuits, e.g. reading or writing circuits, I/O drivers or bit-line switches
• CPC Class Codes: G11C 14/0036 and the nonvolatile element is a magnetic RAM [MRAM] element or ferromagnetic cell
• CPC Class Codes: G11C 14/0045 and the nonvolatile element is a resistive RAM element, i.e. programmable resistors, e.g. formed of phase change or chalcogenide material
• CPC Class Codes: G11C 2207/00 Indexing scheme relating to arrangements for writing information into, or reading information out from, a digital store
• CPC Class Codes: G11C 5/00 Details of stores covered by group G11C11/00
• CPC Class Codes: G11C 7/10 Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers

Abstract

A NVDRAM includes a first NV element coupled to a first terminal of a second NV element at a transfer node. A volatile cell has a transfer transistor coupled to the transfer node and has a storage node. A first NV line is coupled to the second terminal of the first NV element. Circuitry applies an alternated signal to the transfer node, couples the second terminal of the second non-volatile element to a second NV line, and applies a program signal across the first and second NV lines during a program mode that establishes a logic state. The circuitry applies a read signal across the first and second NV lines, couples the second terminal of the second NV element to the second NV line, and replaces the alternated signal with floating during a restore mode that loads the logic state into the storage node.

Claims

1. A non-volatile dynamic random access memory (NVDRAM), comprising:

a first bit line;

a first non-volatile line;

a second non-volatile line;

a first select line; and

a first NVDRAM cell, comprising;

a first DRAM cell, coupled to the first bit line, comprising;

a first capacitor having a first terminal coupled to a first storage node and a second terminal coupled to a reference; and

a first transfer transistor having a first current electrode coupled to a first power supply terminal, a second current electrode coupled to the first storage node, and a control electrode;

a first pass gate transistor coupled between the first bit line and the first storage node;

a first non-volatile element having a first terminal coupled to the control electrode of the first transfer transistor and a second terminal coupled to the first non-volatile line;

a second non-volatile element having a first terminal coupled to the control electrode of the first transfer transistor and a second terminal;

a first switching transistor having a first current electrode for receiving a first program signal, a second current electrode coupled to the control electrode of the first transfer transistor, and a control electrode coupled to the first select line; and

a second switching transistor having a first current electrode coupled to the second terminal of the second non-volatile element, a second current electrode coupled to the second non-volatile line, and a control electrode coupled to the first select line.

2. The NVDRAM of claim 1, wherein the NVDRAM further comprises a first word line, wherein the first pass gate transistor has a control electrode coupled to the first word line.

3. The NVDRAM of claim 1, wherein the first non-volatile element comprises a first programmable resistor.

4. The NVDRAM of claim 3, wherein the first programmable resistor comprises a RRAM resistor.

5. The NVDRAM of claim 3, wherein the programmable resistor comprises a STT-RAM MTJ.

6. The NVDRAM of claim 1, further comprising:

a second bit line;

a third non-volatile line;

a fourth non-volatile line; and

a second NVDRAM cell, comprising;

a second DRAM cell, coupled to the first bit line, comprising;

a second capacitor having a first terminal coupled to a second storage node and a second terminal coupled to the reference; and

a second transfer transistor having a first current electrode coupled to the first power supply terminal, a second current electrode coupled to the second storage node, and a control electrode;

a second pass gate transistor coupled between the second bit line and the second storage node;

a third non-volatile element having a first terminal coupled to the control electrode of the second transfer transistor and a second terminal coupled to the third non-volatile line;

a fourth non-volatile element having a first terminal coupled to the control electrode of the second transfer transistor and a second terminal;

a third switching transistor having a first current electrode for receiving a second program signal, a second current electrode coupled to the control electrode of the second transfer transistor, and a control electrode coupled to the first select line; and

a fourth switching transistor having a first current electrode coupled to the second terminal of the fourth non-volatile element, a second current electrode coupled to the fourth non-volatile line, and a control electrode coupled to the first select line.

7. The NVDRAM of claim 6, wherein the NVDRAM further comprises a first word line, wherein the first pass gate transistor has a control electrode coupled to the first word line and the second pass gate transistor has a control electrode coupled to the first word line.

8. The NVDRAM of claim 6, further comprising:

a second select line; and

a third NVDRAM cell, comprising;

a third DRAM cell, coupled to the first bit line, comprising;

a third capacitor having a first terminal coupled to a third storage node and a second terminal coupled to the reference; and

a third transfer transistor having a first current electrode coupled to the first power supply terminal, a second current electrode coupled to the third storage node, and a control electrode;

a third pass gate transistor coupled between the first bit line and the third storage node;

a fifth non-volatile element having a first terminal coupled to the control electrode of the third transfer transistor and a second terminal coupled to the first non-volatile line;

a sixth non-volatile element having a first terminal coupled to the control electrode of the third transfer transistor and a second terminal;

a third switching transistor having a first current electrode for receiving the first program signal, a second current electrode coupled to the control electrode of the third transfer transistor, and a control electrode coupled to the second select line; and

a fourth switching transistor having a first current electrode coupled to the second terminal of the fourth non-volatile element, a second current electrode coupled to the fourth non-volatile line, and a control electrode coupled to the second select line.

9. The NVDRAM of claim 8, wherein the NVDRAM further comprises a first word line and a second word line, wherein the first pass gate transistor has a control electrode coupled to the first word line, the second pass gate transistor has a control electrode coupled to the first word line, and the third pass gate transistor has a control electrode coupled to the second word line.

10. The NVDRAM of claim 9, further comprising:

a first decoder coupled to the first bit line, the second bit line, the first non-volatile line, the second non-volatile line, the third non-volatile line, and a fourth non-volatile line.

11. The NVDRAM of claim 10, further comprising a multiplexer coupled to the first decoder for providing output data.

12. The NVDRAM of claim 11, further comprising a row decoder coupled to the first word line, the second word line, the first select line, and the second select line.

13. A method of operating a non-volatile dynamic random access memory (NVDRAM) cell having a first non-volatile element having a first terminal coupled to a first terminal of a second non-volatile element at a transfer node, the first and second non-volatile elements having second terminals, comprising:

programming the first non-volatile element and the second non-volatile element by applying a voltage differential to the second terminals of the first and second non-volatile elements while providing an alternated voltage at the transfer node to result in a logic state represented by a resistance differential between the first non-volatile element and the second non-volatile element;

transferring the logic state to a storage node through a transfer transistor coupled to the transfer node and the storage node; and

reading the logic state by coupling the storage node to a bit line through a pass gate transistor.

14. The method of claim 13, wherein the programming is further characterized by the voltage differential being applied across a first non-volatile line and a second non-volatile line, the second terminal of the first non-volatile element being coupled to the first non-volatile line, and the second terminal of the second non-volatile element being coupled to the second non-volatile line and the alternated voltage being applied to the to the transfer node in response to a program signal being enabled.

15. The method of claim 14, wherein the transferring is further characterized by applying a restore signal across the first non-volatile line and the second non-volatile line while coupling the second terminal of the second non-volatile element to the second non-volatile line.

16. The method of claim 15, wherein the transferring is further characterized by a control electrode of the transfer transistor being coupled to the transfer node.

17. The method of claim 14, wherein during the transferring, the alternated voltage applied during the programming is replaced with floating.

18. A non-volatile dynamic random access memory (NVDRAM), comprising:

a first non-volatile element having a first terminal coupled to a first terminal of a second non-volatile element at a transfer node, the first and second non-volatile elements having second terminals;

a DRAM cell having a transfer transistor and a storage node, wherein the transfer transistor is coupled to the storage node and the transfer node;

a first non-volatile line coupled to the second terminal of the first non-volatile element and a second non-volatile line; and

circuitry that, during a program mode, applies an alternated signal to the transfer node, couples the second terminal of the second non-volatile element to the second non-volatile line, and applies a program signal across the first and second non-volatile lines and that, during a restore mode, applies a read signal across the first and second non-volatile lines, couples the second terminal of the second non-volatile element to the second non-volatile line, and replaces the alternated signal with floating, in which a logic state represented the first and second non-volatile elements that have been programmed is loaded from the transfer node to the storage node.

19. The NVDRAM of claim 18, further comprising a pass gate coupled between a bit line and the storage node that is used to couple the bit line to the storage node that enables reading the logic state.