Very small swing high performance CMOS static memory (multi-port register file) with power reducing column multiplexing scheme

• US 6,519,204 B2
• Filed: 09/27/2001
• Issued: 02/11/2003
• Est. Priority Date: 11/03/2000
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Djaja, Gregory, Smith, Douglas D., Slamowitz, Mark, Knebelsberger, David W.
• Primary Examiner(s): Elms, Richard
• Assistant Examiner(s): PHUNG, ANH K
• Application Number:
  US09/964,971
• Publication Number:
  US 20020071333A1
• Time in Patent Office: 502 Days
• Field of Search: 365/230.05, 365/154, 365/189.02, 365/189.12, 365/205, 365/207, 365/230.02, 327/51, 327/52
• US Class Current: 365/230.05
• CPC Class Codes: G11C 11/412 using field-effect transistors only
• CPC Class Codes: G11C 11/419 Read-write [R-W] circuits

Abstract

Devices and methods relating to a multi-port register file memory including a plurality of storage elements in columns are disclosed. The storage elements are arranged in rows and columns and store data. At least one read port is coupled to each of the storage elements and a sensing device is coupled to the read port. The read port is coupled to the storage elements in an isolated manner, enabling a plurality of cells to be arranged in such rows and columns. The sensing device is adapted to sense a small voltage swing. A pair of series transistors coupled together act as the read port while a column mux circuit is coupled to each column and the sensing device. The sensing device includes two inverters comprising input offset and gain stages. An offset device biases the local bitlines at a voltage close to the sense amplifier trip point.

Claims

1. A multi-port register file memory, the memory comprising:

at least one storage element;

at least one read port coupled to said storage element; and

a sensing device comprising input offset and gain stages coupled to said read port and adapted to sense a small voltage swing.

2. The register file memory of claim 1, wherein said input offset stage biases at least one bitline in relationship to a trip point of said gain stage.

3. The register file memory of claim 1, wherein said input offset stage biases said gain stage, defining a small bitline swing about a trip point of said gain stage.

4. The register file memory of claim 3, wherein said bitline swing is at least a portion of the total voltage supply.

5. The register file memory of claim 1, wherein said input offset stage includes a low power input offset stage adapted to bias at least all local bitlines close in voltage to a trip point of said gain stage.

6. The register file memory of claim 5, wherein said low power input offset stage comprises Pfet and Nfet transistors coupled together.

7. The register file memory of claim 1, wherein said read port comprises a pair of series transistors coupled together.

8. The register file memory of claim 7, wherein said read port comprises two NFet transistors coupled together.

9. The register file memory of claim 8, wherein a gate of one of said NFet transistors is coupled to said storage element.

10. The register file memory of claim 8, wherein one of said NFet transistors acts as a select switch.

11. The register file memory of claim 7, wherein said pair of series transistors are coupled to said storage element in an isolated manner.

12. The register file memory of claim 11, wherein said pair of series transistors comprise at least two transistors coupled to said storage element via a gate of one of said two transistors.

13. The register file memory of claim 1, including a plurality of storage elements arranged in columns.

14. The register file memory of claim 13, including a plurality of read ports, wherein one read port is coupled to each said storage element.

15. The register file memory of claim 13, including a column mux circuit coupled to at least one of said columns.

16. The register file memory of claim 15, wherein said column mux circuit is coupled to said sensing device.

17. The register file memory of claim 1, wherein said sensing device comprises Pfet and Nfet transistors coupled together.

18. The register file memory of claim 1, wherein said sensing device comprises two PFet transistors coupled together.

19. The register file memory of claim 1, wherein said sensing device comprises a PFet transistor and a plurality of NFet transistors coupled together.

20. The register file memory of claim 1, wherein said small voltage swing is about 200 mV.

21. A multi-port register file memory, the memory comprising:

a plurality of storage elements arranged in a plurality of columns, each of said columns having at least one bitline;

at least one read port coupled to said storage element;

a sensing device having a predetermined trip point coupled to said read port and adapted to sense a small voltage swing; and

a biasing device adapted to bias at least one of said bitlines at a predetermined relationship to said trip point.

22. A multi-port register file memory, the memory comprising:

a plurality of storage elements arranged in columns;

means for selecting one of said storage elements; and

means for sensing a small bitline voltage swing, said sensing means comprising input offset and gain stages.

23. The register file memory of claim 22, wherein said selecting means comprises a pair of series transistors coupled together.

24. The register file memory of claim 22, wherein said selecting means comprises at least one NFet transistor having a gate coupled to at least one of said storage elements.

25. The register file memory of claim 22, wherein said selecting means comprises at least one transistor acting as a switch.

26. The register file memory of claim 22, wherein said selecting means includes at least one column mux circuit.

27. The register file memory of claim 26, wherein said input offset stage biases said gain stage, defining a small bitline swing about a trip point of said gain stage.

28. The register file memory of claim 26, wherein said input offset stage includes a low power input offset stage.

29. The register file memory of claim 26, wherein said column mux circuit is coupled to at least one of said columns and said sensing device.

30. A circuit for use with a memory having at least one storage element, the circuit comprising:

a read port coupled to the storage element; and

a sensing amplifier comprising input offset and gain stages coupled to said read port and adapted to sense a small voltage swing.

31. The circuit of claim 30, wherein the read port comprises two NFet transistors coupled together.

32. The circuit of claim 31, wherein a gate of one of said NFet transistors is coupled to the storage element.

33. The circuit of claim 31, wherein one of said NFet transistors acts as a select switch.

34. The register file memory of claim 30, including a column mux circuit coupled to a memory.

35. The register file memory of claim 30, wherein said input offset stage biases said gain stage, defining a small bitline swing about a trip point of said gain stage.

36. A method for improving speed and increasing performance in a multi-port register file memory having a plurality of storage elements, the method comprising:

selecting at least one of said storage elements; and

sensing a small voltage swing using a sensing device comprising input offset and gain stages.

37. The method of claim 36, comprising biasing, using said input offset stage, at least one bitline close in voltage to a trip point of said gain stage.

38. A method for reading data stored in a multi-port register file memory having a plurality of memories arranged in columns, the method comprising:

selecting one of the columns;

flowing a current through at least one transistor to one of the storage elements in said one column;

causing an output of a sense amplifier, comprising input offset and gain stages, connected to at least said column to switch to a high state.

39. The method of claim 38, comprising selecting one of the columns from a plurality of columns using a column mux circuit.

40. The method of claim 38, comprising biasing, using said input offset stage, at least one bitline close in voltage to a trip point of said gain stage.