Integrated circuit memory devices having direct access mode test capability and methods of testing same

• US 6,046,947 A
• Filed: 11/24/1998
• Issued: 04/04/2000
• Est. Priority Date: 12/03/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Chai, Joon-wan, Kyung, Kye-hyun
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): PHUNG, ANH K
• Application Number:
  US09/198,702
• Time in Patent Office: 497 Days
• Field of Search: 365/201, 365/189.05, 365/189.02, 365/230.05, 365/230.08
• US Class Current: 365/201
• CPC Class Codes: G11C 29/32 Serial access; Scan testing
• CPC Class Codes: G11C 29/48 Arrangements in static stores specially adapted for testing by means external to the store, e.g. using direct memory access [DMA] or using auxiliary access paths

Abstract

Integrated circuit memory devices include test mode control circuits to more efficiently route test data to a fewer number of output pins during test mode operation. The memory device may include first and second memory arrays having first and second pluralities of data lines electrically coupled thereto, respectively. First and second pluralities of latch units are also provided. The first plurality of latch units are electrically coupled together in series as a first pipelined latch unit and electrically coupled in parallel to the first memory array by the first plurality of data lines. The second plurality of latch units are electrically coupled together in series as a second pipelined latch unit and electrically coupled in parallel to the second memory array by the second plurality of data lines. A preferred test mode control circuit electrically couples an output of the first pipelined latch unit to an input of the second pipelined latch unit, in response to a test mode control signal (φDAE). This test mode control circuit enables the transfer of data from the first pipelined latch unit to the second pipelined latch unit during direct access test mode reading operations. This data can then be transferred from the first pipelined latch unit to an output driver and then serially transmitted to a single input/output pin. Additional memory arrays within the memory device may also be linked together during test mode operation to improve testing efficiency when multiple memory devices are tested simultaneously in a memory testing apparatus.

Claims

1. An integrated circuit memory device, comprising:

a first memory array having a first plurality of data lines electrically coupled thereto;

a second memory array having a second plurality of data lines electrically coupled thereto;

a first plurality of latch units electrically coupled together in series as a first pipelined latch unit and electrically coupled in parallel to said first memory array by the first plurality of data lines;

a second plurality of latch units electrically coupled together in series as a second pipelined latch unit and electrically coupled in parallel to said second memory array by the second plurality of data lines; and

a test mode control circuit which electrically couples an output of the first pipelined latch unit to an input of the second pipelined latch unit, in response to a test mode control signal.

2. The memory device of claim 1, wherein said test mode control circuit comprises a tri-state buffer having an input electrically coupled to the output of the first pipelined latch unit and an output electrically coupled to the input of the second pipelined latch unit.

3. The memory device of claim 2, further comprising a pass transistor which is electrically coupled in series between the output of said tri-state buffer and a first reference potential and is responsive to the test mode control signal.

4. The memory device of claim 1, wherein the second pipelined latch unit comprises a latch unit cell which is responsive to a test clock signal and a test read signal and has a first data input electrically coupled to a first one of the first plurality of data lines and a second data input electrically coupled to an output of said test mode control circuit.

5. The memory device of claim 4, wherein the latch unit cell comprises:

a first D-type latch having a data input terminal electrically coupled to the first data input of the latch unit cell;

a multiplexer having a first input terminal electrically coupled to an output terminal of the first D-type latch and a second input terminal electrically coupled to the second data input of the latch unit cell; and

a second D-type latch having a data input terminal electrically coupled to an output of the multiplexer.

6. The memory device of claim 5, wherein the first D-type latch has an enable input which is responsive to the test read signal;

and wherein the second D-type latch has a clock input which is responsive to the test clock signal.

7. The memory device of claim 6, wherein the first D-type latch is a non-gated latch;

and wherein the second D-type latch is a gated latch.

8. The memory device of claim 5, wherein the multiplexer has a select input which is responsive to the test read signal.

9. The memory device of claim 6, wherein the multiplexer has a select input which is responsive to the test read signal.

10. The memory device of claim 9, wherein said test mode control circuit comprises a tri-state buffer having an input electrically coupled to the output of the first pipelined latch unit and an output electrically coupled to the input of the second pipelined latch unit.

11. The memory device of claim 10, further comprising a pass transistor which is electrically coupled in series between the output of said tri-state buffer and a first reference potential and is responsive to the test mode control signal.

12. An integrated circuit memory device, comprising:

a first memory array having a first plurality of even and odd data lines electrically coupled thereto;

a second memory array having a second plurality of even and odd data lines electrically coupled thereto;

a first plurality of odd latch units electrically coupled together in series as a first odd pipelined latch unit and electrically coupled in parallel to said first memory array by the first plurality of odd data lines;

a first plurality of even latch units electrically coupled together in series as a first even pipelined latch unit and electrically coupled in parallel to said first memory array by the first plurality of even data lines;

a second plurality of odd latch units electrically coupled together in series as a second odd pipelined latch unit and electrically coupled in parallel to said second memory array by the second plurality of odd data lines;

a second plurality of even latch units electrically coupled together in series as a second even pipelined latch unit and electrically coupled in parallel to said second memory array by the second plurality of even data lines;

first test mode control circuit which electrically couples an output of the first odd pipelined latch unit to an input of the second odd pipelined latch unit, in response to a test mode control signal; and

a second test mode control circuit which electrically couples an output of the first even pipelined latch unit to an input of the second even pipelined latch unit, in response to the test mode control signal.

13. The memory device of claim 12, further comprising:

a first multiplexer having a select input responsive to a test clock signal, a first data input electrically coupled to the output of the first odd pipelined latch unit and a second data input electrically coupled to the output of the first even pipelined latch unit; and

a second multiplexer having a select input responsive to the test clock signal, a first data input electrically coupled to an output of the second odd pipelined latch unit and a second data input electrically coupled to an output of the second even pipelined latch unit.

14. The memory device of claim 12, wherein said first test mode control circuit comprises a tri-state buffer having an input electrically coupled to the output of the first odd pipelined latch unit and an output electrically coupled to the input of the second odd pipelined latch unit.

15. The memory device of claim 14, further comprising a pass transistor electrically coupled in series between the output of said tri-state buffer and a first reference potential and responsive to the test mode control signal.

16. The memory device of claim 12, wherein the second odd pipelined latch unit comprises a latch unit cell which is responsive to a test clock signal and a test read signal and has a first data input electrically coupled to a first one of the second plurality of odd data lines and a second data input electrically coupled to an output of said first test mode control circuit.

17. The memory device of claim 12, wherein said second test mode control circuit comprises a tri-state buffer having an input electrically coupled to the output of the first even pipelined latch unit and an output electrically coupled to the input of the second even pipelined latch unit.

18. The memory device of claim 17, further comprising a pass transistor electrically coupled in series between the output of said tri-state buffer and a first reference potential and responsive to the test mode control signal.

19. The memory device of claim 12, wherein the second even pipelined latch unit comprises a latch unit cell which is responsive to a test clock signal and a test read signal and has a first data input electrically coupled to a first one of the second plurality of even data lines and a second data input electrically coupled to an output of said second test mode control circuit.

20. The memory device of claim 16, wherein the latch unit cell comprises:

a first D-type latch having a data input terminal electrically coupled to the first one of the second plurality of odd data lines;

a multiplexer having a first input terminal electrically coupled to an output terminal of the first D-type latch and a second input terminal electrically coupled to the output of said first test mode control circuit; and

a second D-type latch having a data input terminal electrically coupled to an output of the multiplexer.

21. The memory device of claim 20, wherein the first D-type latch has an enable input which is responsive to the test read signal;

and wherein the second D-type latch has a clock input which is responsive to the test clock signal.

22. The memory device of claim 21, wherein the first D-type latch is a non-gated latch;

and wherein the second D-type latch is a gated latch.

23. The memory device of claim 20, wherein the multiplexer has a select input which is responsive to the test read signal.

24. The memory device of claim 21, wherein the multiplexer has a select input which is responsive to the test read signal.

25. The memory device of claim 24, wherein said first test mode control circuit comprises a tri-state buffer having an input electrically coupled to the output of the first odd pipelined latch unit and an output electrically coupled to the input of the second odd pipelined latch unit.

26. The memory device of claim 25, further comprising a pass transistor which is electrically coupled in series between the output of said tri-state buffer and a first reference potential and is responsive to the test mode control signal.

27. A method of testing an integrated circuit memory device, comprising the steps of:

transferring data in parallel from first and second memory arrays within the memory device to first and second pipelined latch units, respectively; and

transferring data from the second pipelined latch unit to an output driver while simultaneously transferring data from the first pipelined latch unit into the second pipelined latch unit.