Oscillator controlled random sampling method and circuit
View Patent ↗Various embodiments comprise methods and apparatuses for selecting a randomly-chosen seed row from among a stream of available data in a memory system. A refresh operation is then performed on at least one selected row of memory in the memory system based on the randomly-chosen seed row. Additional apparatuses and methods are described.
1. An apparatus to provide row-hammer repair (RHR) operations in a memory device, the apparatus comprising:
a plurality of frequency dividers to be coupled to a reference oscillator;
a plurality of counter circuits coupled to the reference oscillator; and
a plurality of comparators coupled to the plurality of frequency dividers and the plurality of counter circuits to select a random sample of activation addresses from available data based on a match between latched values of two counters of the plurality of counter circuits; and
a refresh circuit to provide the RHR operations to the memory device based on the random sample.
2. The apparatus of claim 1 , further comprising a selective-increment circuit to select a particular starting time within a sampling window.
3. The apparatus of claim 1 , wherein the apparatus is instantiated in each of multiple banks of a memory device.
4. The apparatus of claim 3 , wherein activation addresses in each of the multiple banks is to be sampled independently from others of the multiple banks.
5. The apparatus of claim 3 , wherein activation addresses in each of the multiple banks is to be sampled at random times from others of the multiple banks.
6. The apparatus of claim 3 , wherein the random sample of activation addresses for a single bank of memory is used to supply RHR refresh signals to one or more of the multiple banks.
7. The apparatus of claim 1 , wherein the reference oscillator has no synchronous relationship to periodic access cycles within the memory device.
8. The apparatus of claim 1 , wherein the refresh circuit is to determine a number of refresh cycles for RHR operations.
9. The apparatus of claim 1 , wherein at least one circuit in the plurality of counter circuits is to latch a most recently sampled activation address to provide the starting point for the RHR operations.
10. The apparatus of claim 9 , wherein at least one circuit in the plurality of counter circuits is configured to make a determination of each address of a row of memory on either side of the activation address.
11. The apparatus of claim 10 , further comprising, based on the determination of each of the addresses of the rows of memory on either side of the most recently sampled activation address, the apparatus is configured to perform a memory refresh operation on each of the rows of memory on either side of the most recently sampled activation address.
12. The apparatus of claim 1 , wherein the apparatus is configured to provide a seed address for a subsequent RHR operation.
13. An apparatus, comprising:
a random-sampling device to couple to and receive a periodic output signal from a reference oscillator, the random-sampling device further to select a randomly-selected target address associated with a plurality of memory cells from a plurality of row addresses sampled from an address bust and
a row-hammer repair (RHR) selector circuit to determine at least one row address proximate the randomly-selected target address the random-sampling device to determine an average RHR time interval based on a time period of refresh cycles and a percentage of the refresh cycles that are to be dedicated to the RHR operations.
14. The apparatus of claim 13 , further comprising a refresh control circuit configured to receive the at least one row address proximate the randomly-selected target address and to provide a row refresh to the proximate address.
15. The apparatus of claim 13 , wherein the random-sampling device is to select a number of predetermined time intervals such that the number of the predetermined tune intervals is greater than the average RIM tune interval.
16. The apparatus of claim 13 , wherein the random-sampling device is configured to:
select a first randomly-chosen seed row within a first predetermined time interval; and
record a value of the first randomly-chosen seed row.
17. The apparatus of claim 16 , wherein the random-sampling device is further configured to:
select a second randomly-chosen seed row within a second predetermined time interval;
overwrite the value of the first randomly-chosen seed row; and
record a value of the second randomly-chosen seed row.