Apparatus and methods for triggering row hammer address sampling
Apparatuses and methods for triggering row hammer address sampling are described. An example apparatus includes an oscillator circuit configured to provide a clock signal, and a filter circuit. The filter circuit includes a control circuit configured to receive pulses of the clock signal and provide an output signal that represents a count number by counting a number of pulses of the clock signal and control a probability of enabling the output signal based on the count number. The filter circuit further includes a logic gate configured to pass one of the pulses of the clock signal responsive to the output signal from the control circuit being enabled and filter another of the pulses responsive to the output signal from the control circuit being not enabled.
1. An apparatus comprising:
a row hammer control circuit configured to provide a row hammer control signal that indicates a start of a row hammer interval;
a sampling timing generator circuit configured to provide pulses on an trigger sample signal to trigger time-based samples of row addresses in response to the row hammer control signal, wherein the sampling timing generator circuit comprises a filter circuit that is configured to adjust a probability of providing the pulses on the trigger sample signal based on count of previous pulses of the trigger sample signal within the row hammer interval; and
a time-based sampling circuit configured to initiate a respective sample of a row address in response to each of the pulses of the trigger sample signal, wherein a probability of capturing a valid row address is constant for each of the pulses of the trigger sample signal.
2. The apparatus of claim 1 , further comprising an oscillator circuit configured to provide the pulses on a clock signal, wherein the sampling timing generator circuit is configured to provide the pulses on the trigger sample signal based on the pulses of the clock signal.
3. The apparatus of claim 1 , wherein the filter circuit comprises a counter circuit configured to provide a count value, wherein the count value is incremented with based on a clock signal, wherein the probability that the filter circuit triggers a pulse on the trigger sample signal is based on the count value.
4. The apparatus of claim 3 , wherein the filter circuit further comprises a linear-feedback shift register to provide a pseudo-random number, wherein the pulse on the trigger sample signal is based on whether the count value is a divisor of the pseudo-random number.
5. The apparatus of claim 4 , wherein the linear-feedback shift register is configured to adjust the pseudo-random number in response to a row active command signal or a refresh signal.
6. The apparatus of claim 3 , wherein the filter circuit includes a free-running counter circuit configured to provide a second count value, wherein the filter circuit is configured to trigger a pulse on the trigger sample signal in response to the count value matching the second count value.
7. The apparatus of claim 3 , wherein the filter circuit includes a logic gate configured to reset the free-running counter in response the count value matching the second count value.
8. The apparatus of claim 3 , wherein the filter circuit is configured to decrease the probability of providing a pulse on the trigger sample signal as the count value increases.
9. An apparatus comprising:
a sampling timing generator circuit configured to provide pulses on an trigger sample signal to trigger time-based samples of row addresses in response to a pulse on a row hammer control signal provided by row hammer control circuit indicating a state of a row hammer interval, wherein the sampling timing generator circuit is configured to adjust a probability of providing the pulses on the trigger sample signal based on count of previous pulses of the trigger sample signal within the row hammer interval; and
a time-based sampling circuit configured to initiate a respective sample of a row address in response to each of the pulses of the trigger sample signal, wherein a probability of capturing a valid row address is constant for each of the pulses of the trigger sample signal.
10. The apparatus of claim 9 , wherein the sampling timing generator circuit is configured to provide a count value that is incremented with based on a clock signal, wherein the probability that the sampling timing generator circuit triggers a pulse on the trigger sample signal is based on the count value.
11. The apparatus of claim 9 , wherein the sampling timing generator circuit is configured to provide the pulse on the trigger sample signal based on whether the count value is a divisor of a generated pseudo-random number.
12. The apparatus of claim 3 , wherein the sampling timing generator circuit is further configured to provide a second count value and to trigger a pulse on the trigger sample signal in response to the count value matching the second count value.
13. A method comprising:
receiving, at a sampling timing generator circuit from a row hammer control circuit, a row hammer control signal that indicates a start of a row hammer interval;
providing pulses on a trigger sample signal to trigger time-based samples of row addresses in response to the row hammer control signal;
adjusting, via a filter circuit of the sampling timing generator circuit, a probability of providing the pulses on the trigger sample signal based on count of previous pulses of the trigger sample signal within the row hammer interval; and
initiating, via a time-based sampling circuit, a respective sample of a row address in response to each of the pulses of the trigger sample signal, wherein a probability of capturing a valid row address is constant for each of the pulses of the trigger sample signal.
14. The method of claim 13 , further comprising providing the pulses on the trigger sample signal based on provision of pulses of a clock signal by an oscillator circuit.
15. The method of claim 13 , further comprising providing, via the filter circuit, a count value that is incremented with based on a clock signal, wherein the probability that the filter circuit triggers a pulse on the trigger sample signal is based on the count value.
16. The method of claim 15 , further comprising:
generating a pseudo-random number; and
providing the pulse on the trigger sample signal based on the count value being a divisor of the pseudo-random number.
17. The method of claim 16 , further comprising adjusting the pseudo-random number in response to a row active command signal or a refresh signal.
18. The method of claim 15 , further comprising:
providing, via the filter circuit, a second count value; and
triggering the pulse on the trigger sample signal in response to the count value matching the second count value.
19. The method of claim 18 , further comprising resetting the second count value in response the count value matching the second count value.
20. The method of claim 15 , further comprising decreasing the probability of providing a pulse on the trigger sample signal in response to an increase in the count value.