RAM memory circuit having a plurality of banks and an auxiliary device for testing

• US 20050152194A1
• Filed: 12/14/2004
• Published: 07/14/2005
• Est. Priority Date: 06/14/2002
• Status: Active Grant

• Current Assignee: Polaris Innovations Limited (Wi-LAN Inc.)
• Original Assignee: Qimonda AG (Infineon Technologies AG)
• Inventors: Pfeiffer, Johann, Boldt, Sven
• Granted Patent: US 6,961,273 B2
• Time in Patent Office: Days
• US Class Current: 365/201
• CPC Class Codes: G11C 2029/2602 Concurrent test
• CPC Class Codes: G11C 29/26 Accessing multiple arrays G11C29/24 takes precedence
• CPC Class Codes: G11C 29/40 using compression techniques

Abstract

One embodiment of the invention provides a RAM memory circuit having k≧2 banks, each of which having a multiplicity of memory cells and a selection device to simultaneously select groups of in each case n≧2 memory cells of the bank for the writing or reading of n parallel data. For the fast testing of all the banks, devices are included for the parallel switching of the banks such that reading and writing may be effected simultaneously at all the banks. For each bank, a dedicated evaluation device is included for comparing the n data respectively read out at the relevant bank with a reference information item, which is representative of the write data which have previously been written in at the currently selected memory cell group of the bank, and for providing a result information item, comprising 1≦m≦n/k bits, each of which indicates whether a subset precisely assigned to it from m subsets of the n read data corresponds to a part of the reference information item which is precisely assigned to said subset.

Claims

1. A random access memory circuit, comprising:

a plurality (k) of banks, each bank having a multiplicity of memory cells and a selection device configured to simultaneously select one or more groups of n memory cells of the respective bank, depending on a cell address information item applied, for one of a write operation and a read operation;

a bidirectional data port having n transfer channels for receiving and transmitting n data bits in parallel, the bidirectional data port selectably connected to a plurality of bank buses which are connected respectively to the plurality of banks; and

a test auxiliary device comprising;

a bus parallel switching device for simultaneously connecting the plurality of bank buses to the data port;

a selection parallel switching device for simultaneously activating the selection devices of the plurality of banks;

a test control circuit, in response to a test mode setting signal, for activating the bus parallel switching device only during the write operation, decoupling the plurality of bank buses from the data port during the read operation and activating the selection parallel switching device during the write operation and during the read operation; and

for each bank, a dedicated evaluation device for comparing n read data of the currently selected group of n memory cells of the respective bank and providing a result information item comprising m bits where 1≦

m≦

n/k, wherein each result information item indicates whether an assigned subset from m subsets of the n read data corresponds to a part of the reference information item which is assigned to the respective subset, wherein each evaluation device comprises m comparators.

2. The random access memory circuit of claim 1, wherein each comparator comprises:

a plurality of signal inputs for receiving a subset of the n read data which is assigned to the respective comparator;

a reference input for receiving a reference bit; and

an output for supplying a result bit which indicates whether all of the n read data received at the signal inputs correspond to the reference bit.

3. The random access memory circuit of claim 2, wherein the test auxiliary device further comprises first connecting means for connecting the output of each comparator to the data port.

4. The random access memory circuit of claim 3, wherein m*k≦

n/2, and wherein the test auxiliary device further comprises second connecting means for connecting the reference input of each comparator to one of the transfer channels of the data port which is not affected by the first connecting means.

5. The random access memory circuit of claim 3, wherein m*k=n, and wherein the test auxiliary device further comprises a reference bit transmitter for providing the reference bits for the reference inputs of the m comparators simultaneously in all evaluation devices during the read operation.

6. The random access memory circuit of claim 5, wherein the reference bit transmitter is set, via a connection to the transfer channels of the data port, to the binary values of selected bits of the write data received on the respective transfer channels during the write operation.

7. The random access memory circuit of claim 1, wherein the memory cells of each bank are arranged in rows and columns, wherein each selection device is configured such that a quadruple of memory cells is selected via a common column select control line, and wherein a cardinal number of each subset is equal to 4 and each subset of the n read data is individually assigned to one quadruple of memory cells.

8. A random access memory circuit, comprising:

k≧

2 banks, each bank having a multiplicity of memory cells and a selection device configured to simultaneously select one or more groups of n≧

2 memory cells of the respective bank depending on a cell address information item applied and, at each respectively selected memory cell group, to write in a group of n data, via an assigned n-bit bank bus, as write data in a write operation and to read out the group of n data as read data in a read operation;

a bidirectional data port having n transfer channels for receiving and transmitting n parallel data, the bidirectional data port being connected to a plurality of selectable bank buses; and

a test auxiliary device comprising;

a bus parallel switching device for simultaneously connecting all k bank buses to the data port;

a selection parallel switching device for simultaneously activating the selection devices of all banks;

a test control circuit, which responds to a test mode setting signal to activate the bus parallel switching device only during the write operation, to decouple all the bank buses from the data port during the read operation and to activate the selection parallel switching device during the write operation and during the read operation; and

for each bank, a dedicated evaluation device for comparing the n read data of the currently selected group of n memory cells of the bank, which data simultaneously appear on the assigned bank bus with a reference information item which is representative of the write data which have previously been written to the currently selected group of n memory cells, and for providing a result information item comprising m bits, where 1≦

m≦

n/k bits, wherein each result information item indicates whether an assigned subset from m subsets of the n read data corresponds to a part of the reference information item which is assigned to the respective subset,

wherein each evaluation device contains m comparators, each comparator comprising;

a plurality of signal inputs for receiving a subset of the n read data which is assigned to the respective comparator;

a reference input for receiving a reference bit; and

an output for supplying a result bit which indicates whether all of the read data received at the signal inputs correspond to the reference bit.

9. The random access memory circuit of claim 8, wherein the test auxiliary device further comprises first connecting means for connecting an output of each of the m*k comparators to one of the n transfer channels of the data port which is respectively assigned to the comparator.

10. The random access memory circuit of claim 9, wherein m*k≦

n/2, and wherein the test auxiliary device further comprises second connecting means for connecting the reference input of each of the m*k comparators to one of the transfer channels of the data port which is not affected by the first connecting means.

11. The random access memory circuit of claim 9, wherein m*k=n, and wherein the test auxiliary device further comprises a reference bit transmitter for providing the reference bits for the reference inputs of the m comparators simultaneously in all k evaluation devices during the read operation.

12. The random access memory circuit of claim 11, wherein the reference bit transmitter is set, via a connection to the transfer channels of the data port, to the binary values of selected bits of the write data received on the respective transfer channels during the write operation.

13. The random access memory circuit of claim 8, wherein the memory cells of each bank are arranged in rows and columns and each of the selection devices are configured such that a quadruple of memory cells is in each case selected via a common column select control line, and wherein a cardinal number of each subset is equal to 4 and each subset of the n read data is individually assigned in each case to one of the quadruples of memory cells.

14. A test auxiliary device for testing a memory circuit, comprising:

a bus parallel switching device for simultaneously connecting a plurality of bank buses connected respectively to k memory banks to a bidirectional data port having n transfer channels;

a selection parallel switching device for simultaneously activating a plurality of selection devices of the memory banks for one of a writing operation and a reading operation;

a test control circuit, in response to a test mode setting signal, for activating the bus parallel switching device only during the write operation, decoupling the plurality of bank buses from the data port during the read operation and activating the selection parallel switching device during the write operation and during the read operation; and

for each bank, a dedicated evaluation device for comparing n read data of a currently selected group of n memory cells of the respective bank and providing a result information item comprising m bits, where 1≦

m≦

n/k, wherein each result information item indicates whether an assigned subset from m subsets of the n read data corresponds to a part of the reference information item which is assigned to the respective subset, wherein each evaluation device comprises m comparators.

15. The test auxiliary device of claim 14, wherein each comparator comprises:

a plurality of signal inputs for receiving a subset of the n read data which is assigned to the respective comparator;

a reference input for receiving a reference bit; and

an output for supplying a result bit which indicates whether all of the n read data received at the signal inputs correspond to the reference bit.

16. The test auxiliary device of claim 15, further comprising first connecting means for connecting the output of each comparator to the data port.

17. The test auxiliary device of claim 16, further comprising second connecting means for connecting the reference input of each comparator to one of the transfer channels of the data port which is not affected by the first connecting means.

18. The test auxiliary device of claim 16, further comprising a reference bit transmitter for providing the reference bits for the reference inputs of the m comparators simultaneously in all evaluation devices during the read operation.

19. The test auxiliary device of claim 18, wherein the reference bit transmitter is set, via a connection to the transfer channels of the data port, to the binary values of selected bits of the write data received on the respective transfer channels during the write operation.

20. The test auxiliary device of claim 14, wherein the test auxiliary device is integrated with the memory circuit.