Antifuse latch device with controlled current programming and variable trip point

• US 6,384,666 B1
• Filed: 03/23/2001
• Issued: 05/07/2002
• Est. Priority Date: 03/23/2001
• Status: Expired due to Term

• Current Assignee: X Corp. (f/k/a Twitter, Inc.) (X Holdings Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Bertin, Claude L., Fifield, John A., Houghton, Russell J., van Heel, Nicholas M.
• Primary Examiner(s): TRAN, TOAN V
• Application Number:
  US09/816,030
• Time in Patent Office: 410 Days
• Field of Search: 327/525, 327/526, 327/199, 327/208, 365/96, 365/225.7
• US Class Current: 327/525
• CPC Class Codes: G11C 17/18 Auxiliary circuits, e.g. for writing into memory

Abstract

A latch device is provided having a variable resistive trip point and controlled current programming. The latch device has a trip point current control element that controls an amount of current passing from a voltage source into the latch circuit, thereby varying the resistive trip point of the latch device. The latch device also has a programming current control element that controls an amount of programming current passing through the fuse element during programming. The trip point current reference and a programming current reference are provided by reference circuits having a plurality of selectable inputs that operate to change the current references binarily. An integrated circuit is also provided in which a plurality of the fuse latch devices are connected together in parallel such that the same trip point current reference and programming current reference are supplied to each latch device.

Claims

1. A latch device having a variable resistive trip point, comprising:

a voltage source;

an adjustable trip point current reference;

a latch circuit having a fuse latch output; and

a trip point control element, said trip point control element being operable to control the amount of current passing through said latch circuit based on said adjustable trip point current reference, thereby providing the latch device with a variable resistive trip point.

2. The latch device as set forth in claim 1, wherein said trip point control element is a transistor, and wherein a gate of said transistor is connected to said adjustable trip point current reference.

3. The latch device as set forth in claim 2, wherein said transistor has a source connected to said voltage source and a drain connected to said latch circuit, wherein a change in said adjustable trip point current reference changes an amount of current flowing through said transistor into said latch circuit.

4. The latch device as set forth in claim 3, wherein said transistor is an FET.

5. The latch device as set forth in claim 1, wherein said latch circuit is connected to a fuse element.

6. The latch device as set forth in claim 5, wherein said fuse element is an antifuse.

7. The latch device as set forth in claim 1, wherein said adjustable trip point current reference is adjustable binarily.

8. The latch device as set forth in claim 1, further comprising a trip point current reference circuit for developing said adjustable trip point current reference, said trip point current reference circuit having a plurality of selectable inputs for changing the adjustable trip point current reference.

9. The latch device as set forth in claim 8, wherein said plurality of inputs are connected to binarily weighted reference transistors which are operable to change the adjustable trip point current reference binarily.

10. The latch device as set forth in claim 1, further comprising a trip point current reference circuit for developing said adjustable trip point current reference using a current mirror control.

11. The latch device as set forth in claim 1, wherein said latch circuit has a polling transistor comprising a source, a drain and a gate, the gate being connected to a strobe signal input, said polling transistor being operable to poll a fuse connected to the latch circuit when the strobe signal input is in an active state.

12. The latch device as set forth in claim 11, further comprising a trip point current reference circuit for developing said adjustable trip point current reference, and wherein said strobe signal input is connected to a bypass transistor in said trip point current reference circuit to adjust said adjustable trip point current reference to a state in which said trip point control element allows a maximum amount of current to pass from said voltage source into said latch circuit when said strobe signal input is in its inactive state.

13. The latch device as set forth in claim 1, further comprising a trip point current reference circuit for developing said adjustable trip point current reference, said trip point current reference circuit comprising a bandgap current reference.

14. The latch device as set forth in claim 1, wherein said trip point control element is operable to provide the latch device with at least a first trip point for testing a resistance margin of a fuse element, a second trip point for improving soft error immunity, and a third trip point for normal operation.

15. The latch device as set forth in claim 1, further comprising:

a fuse element connected to said latch circuit; and

a programming circuit connected to said fuse element, said programming circuit having a current control element for adjusting an amount of programming current passing through said fuse element, said current control element being controlled by an adjustable current reference.

16. An integrated circuit comprising:

a global trip point control circuit that provides an adjustable trip point current reference; and

a plurality of fuse latch devices, each fuse latch device comprising a latch circuit having a fuse latch output and a trip point control element, said trip point control elements being connected in parallel to said adjustable trip point current reference and being operable to control an amount of current passing through each of said latch circuits based on said adjustable trip point current reference.

17. The integrated circuit as set forth in claim 16, wherein said global trip point control circuit comprises a plurality of selectable inputs which are operable to change the adjustable trip point current reference binarily.

18. The integrated circuit as set forth in claim 16, further comprising:

a global programming current control circuit that provides an adjustable programming current reference; and

each fuse latch device having a fuse element and a programming current control device, said programming current control devices being connected in parallel to said adjustable programming current reference and being operable to control an amount of programming current passing through each of said fuse elements based on said adjustable programming current reference.

19. The integrated circuit as set forth in claim 18, wherein said global programming current control circuit comprises a plurality of selectable inputs which are operable to change the adjustable programming current reference binarily.