Semiconductor device and failure detection method
The present invention provides a semiconductor device and a failure detection method capable of detecting an excessive variation among elements that constitute an analog circuit as a failure. According to an embodiment, a semiconductor device 1 includes: an AD converter 11 ; a digital assist circuit 12 that corrects an error of a digital signal Do corresponding to an analog signal Ain processed by the AD converter 11 ; and a failure detection circuit 13 that detects whether the AD converter 11 has a failure based on a correction amount by the digital assist circuit. The semiconductor device 1 is therefore able to detect the excessive variation among the elements that constitute the AD converter 11 as a failure.
1. A semiconductor device, comprising:
an analog circuit;
a digital assist circuit that corrects an error of a digital signal corresponding to an analog signal processed by the analog circuit; and
a failure detection circuit that detects whether the analog circuit has a failure based on a correction amount by the digital assist circuit, wherein the failure detection circuit detects a failure by evaluating one of:
whether a weight coefficient Eo exceeds a predesignated threshold;
whether a deviation from an average amount of the weight coefficient Eo exceeds a predesignated threshold;
whether a radix (a ratio of weight coefficients of adjacent bits) of an AD converter exceeds a predesignated threshold; and
whether a p-radix (an addition or subtraction of weight coefficients of adjacent bits) of the AD converter exceeds a predesignated threshold.
2. The semiconductor device according to claim 1 , wherein the failure detection circuit determines that the analog circuit has a failure when the correction amount is larger than a predetermined threshold.
3. The semiconductor device according to claim 1 , wherein the failure detection circuit determines that the analog circuit has a failure when a difference between the correction amount and an initial correction amount, which is the correction amount before the analog circuit is used in a normal operation, is larger than a predetermined threshold.
4. The semiconductor device according to claim 3 , further comprising a storage unit that stores the initial correction amount.
5. The semiconductor device according to claim 4 , wherein the storage unit is a programmable nonvolatile memory.
6. The semiconductor device according to claim 3 , wherein the initial correction amount is stored in a storage unit outside of the semiconductor device.
7. The semiconductor device according to claim 1 , wherein:
the analog circuit is an analog-to-digital (AD) converter; and
the digital assist circuit corrects a non-linear error of the digital signal output from the AD converter corresponding to the analog signal input to the AD converter.
8. A semiconductor system comprising:
The semiconductor device according to claim 1 ; and
a higher system that performs predetermined processing for the semiconductor device based on the result of the detection of the failure output from the semiconductor device.
9. A failure detection method, comprising:
correcting an error of a digital signal corresponding to an analog signal processed by an analog circuit using a digital assist circuit; and
detecting whether the analog circuit has a failure based on a correction amount by the digital assist circuit,
wherein the digital assist circuit comprises:
a weight coefficient calculation unit; and
a correction unit.
10. The failure detection method according to claim 9 , wherein it is determined that the analog circuit has a failure when the correction amount is larger than a predetermined threshold.
11. The failure detection method according to claim 9 , wherein it is determined that the analog circuit has a failure when a difference between the correction amount and an initial correction amount, which is the correction amount before the analog circuit is used in a normal operation, is larger than a predetermined threshold.
12. The failure detection method according to claim 11 , further comprising storing the initial correction amount in a storage unit provided on a same semiconductor chip on which the analog circuit is mounted.
13. The failure detection method according to claim 12 , wherein the storage unit is a programmable nonvolatile memory.
14. The failure detection method according to claim 11 , further comprising storing the initial correction amount in a storage unit provided on a semiconductor chip different from a semiconductor chip on which the analog circuit is mounted.
15. The semiconductor device according to claim 7 , wherein the digital assist circuit corrects a non-linear error of the digital signal output by determining and providing a correction amount Eo of a weight coefficient of the AD converter, and
wherein the failure detection circuit detects whether the analog circuit has a failure based on whether the correction amount Eo is larger than a predetermined threshold.
16. The semiconductor device according to claim 7 , wherein a variation of elements constituting the AD converter provides a radix<2.
17. A semiconductor device, comprising:
an analog circuit
a digital assist circuit that corrects an error of a digital signal corresponding to an analog signal processed by the analog circuit; and
a failure detection circuit that detects whether the analog circuit has a failure based on a correction amount by the digital assist circuit,
wherein the analog circuit comprises an analog-to-digital (AD) converter and wherein a variation of elements constituting the AD converter is smaller than 0.5 of a least significant bit (LSB) of the AD converter.
18. The semiconductor device according to claim 1 , wherein the analog circuit comprises one of:
a successive approximation analog-to-digital (AD) converter;
a pipeline type AD converter;
a flash type AD converter; and
an analog circuit in which a correction can be performed by the digital assist circuit.