Data-sampling integrity check by sampling using flip-flops with relative delay
An electronic device includes a combinational logic circuit, one or more functional state-sampling components, one or more protection state-sampling components, and protection logic. The combinational logic circuit has one or more outputs. The functional state-sampling components are configured to sample the respective outputs of the combinational logic circuit. The protection state-sampling components are associated respectively with the functional state-sampling components, each protection state-sampling component configured to sample a same output of the combinational logic circuit as the corresponding functional state-sampling component, but with a predefined time offset relative to the functional state-sampling component. The protection logic is configured to detect a discrepancy between the outputs sampled by the functional state-sampling components and the respective outputs sampled by the protection state-sampling components, and to initiate a responsive action in response to the discrepancy.
1. An electronic device, comprising:
a combinational logic circuit comprising one or more outputs;
one or more functional state-sampling components, configured to sample the respective outputs of the combinational logic circuit;
one or more protection state-sampling components that are associated respectively with the functional state-sampling components, each protection state-sampling component configured to sample a same output of the combinational logic circuit that is also sampled by the corresponding functional state-sampling component, but with a predefined time offset relative to the functional state-sampling component; and
protection logic, configured to detect a discrepancy between the outputs sampled by the functional state-sampling components and the respective outputs sampled by the protection state-sampling components, and to initiate a responsive action in response to the discrepancy.
2. The electronic device according to claim 1 , and comprising a delay element that is configured to delay an output of the combinational logic circuit so as to produce a delayed output, wherein a functional state-sampling component is configured to sample one of the output and the delayed output, and wherein a corresponding protection state-sampling component is configured to sample the other of the output and the delayed output.
3. The electronic device according to claim 1 , and comprising a delay element that is configured to delay a clock signal so as to produce a delayed clock signal, wherein a functional state-sampling component is configured to be clocked by one of the clock signal and the delayed clock signal, and wherein a corresponding protection state-sampling component is configured to be clocked by the other of the clock signal and the delayed clock signal.
4. The electronic device according to claim 1 , wherein a functional state-sampling component and a corresponding protection state-sampling component comprise Flip-Flops (FFs).
5. The electronic device according to claim 1 , wherein a functional state-sampling component comprises a first latch that drives a second latch, and wherein a corresponding protection state-sampling component comprises a third latch associated with the first latch.
6. The electronic device according to claim 1 , wherein the protection logic is configured to consolidate multiple discrepancies detected between two or more of the functional state-sampling components and two or more of the protection state-sampling components, and to initiate the responsive action in response to the consolidated discrepancies.
7. The electronic device according to claim 1 , wherein the protection logic is configured to initiate the responsive action only when the detected discrepancy occurs during a predefined portion of a clock cycle.
8. The electronic device according to claim 1 , wherein a functional state-sampling component is configured to sample an output of the combinational logic circuit with a first threshold voltage, and wherein a corresponding protection state-sampling component is configured to sample the same output of the combinational logic circuit with a second threshold voltage, higher than the first threshold voltage.
9. A method for protecting an electronic device, the method comprising:
sampling one or more outputs of a combinational logic circuit using one or more respective functional state-sampling components;
sampling the one or more outputs using one or more protection state-sampling components that are associated respectively with the functional state-sampling components, wherein each protection state-sampling component samples a same output of the combinational logic circuit that is also sampled by the corresponding functional state-sampling component, but with a predefined time offset relative to the functional state-sampling component; and
detecting a discrepancy between the outputs sampled by the functional state-sampling components and the respective outputs sampled by the protection state-sampling components, and initiating a responsive action in response to the discrepancy.
10. The method according to claim 9 , wherein sampling the one or more outputs comprises delaying an output of the combinational logic circuit so as to produce a delayed output, sampling one of the output and the delayed output by a functional state-sampling component, and sampling the other of the output and the delayed output by a corresponding protection state-sampling component.
11. The method according to claim 9 , wherein sampling the one or more outputs comprises delaying a clock signal so as to produce a delayed clock signal, clocking a functional state-sampling component by one of the clock signal and the delayed clock signal, and clocking a corresponding protection state-sampling component by the other of the clock signal and the delayed clock signal.
12. The method according to claim 9 , wherein a functional state-sampling component and a corresponding protection state-sampling component comprise Flip-Flops (FFs).
13. The method according to claim 9 , wherein a functional state-sampling component comprises a first latch that drives a second latch, and wherein a corresponding protection state-sampling component comprises a third latch associated with the first latch.
14. The method according to claim 9 , wherein initiating the responsive action comprises consolidating multiple discrepancies detected between two or more of the functional state-sampling components and two or more of the protection state-sampling components, and initiating the responsive action in response to the consolidated discrepancies.
15. The method according to claim 9 , wherein initiating the responsive action comprises initiating the responsive action only when the detected discrepancy occurs during a predefined portion of a clock cycle.
16. The method according to claim 9 , wherein sampling the one or more outputs comprises sampling an output of the combinational logic circuit by a functional state-sampling component with a first threshold voltage, and sampling the same output of the combinational logic circuit by a corresponding protection state-sampling component with a second threshold voltage, higher than the first threshold voltage.