84
3 SAMPA Chip Implementation
3.4 Error Handling
With the increase in the interaction rate expected for Run 3, the radiation load on
the SAMPA will consequently also increase. The highest radiation environment is
present in the TPC where the high energy hadron flux is expected to reach about
3.4 kHz/cm
2 , compared to 0.8 kHz/cm
2 in Run 1 [21]. High energy hadrons are
the primary source of radiation-induced SEEs in the ALICE environment. The SEE
issues of primary concern for the SAMPA digital design are Single Event Upset
(SEU), where a particle can flip a bit in a memory element, and Single Event Transient
(SET) where a single particle creates a transient on a line that can further propagate
to a memory element if the event happens close to a clock edge. Both of these issues
can be recovered from by correcting the data either manually or automatically.
Single Event Latch-up (SEL) issues can also occur, where the particle creates a
temporary short between the supply voltage and ground and which needs to be recovered from by power cycling or lowering the supply voltage. This issue is though layout
related and must be mitigated by altering the layout or by substituting problematic
library components by non-affected components and therefore cannot be directly
mitigated on the design level.
Devices in a radiation environment are also affected by dose-related issues that
alter the analogue properties of a design over time, the more dose that is absorbed. As
the expected dose rates for TPC in Run 3 is only 2.1 k rad [21], this is not considered
an issue, as at this level, without considering annealing, the change in analogue
parameters will be low [22].
Errors induced by SEE can be, for the SAMPA, classified according to three
severity levels: data-path errors, configuration errors, and functional errors. Datapath errors are the least severe errors as the errors occur in parts of the circuitry
that are periodically overwritten. The errors are commonly confined to within one
event. Configuration errors are errors that occur in the configuration registers or
pedestal memory and which will alter the operation of the device. These errors will
remain until the device is reset or reconfigured, and so these errors are of a more
severe character. It is, however, possible for the device to operate normally with these
errors, depending on which configurations changed. Functional errors are the most
severe as they can prevent the device from operating properly. These errors might
happen in the state machines, the memory pointers or in certain counters. In the
SAMPA, all parts of the design are protected against SEE, except for the sections
that are part of the data-path and test structures.
Further information on the radiation tolerance and susceptibility of the device can
be found in [23].
3 SAMPA Chip Implementation
3.4 Error Handling
With the increase in the interaction rate expected for Run 3, the radiation load on
the SAMPA will consequently also increase. The highest radiation environment is
present in the TPC where the high energy hadron flux is expected to reach about
3.4 kHz/cm
2 , compared to 0.8 kHz/cm
2 in Run 1 [21]. High energy hadrons are
the primary source of radiation-induced SEEs in the ALICE environment. The SEE
issues of primary concern for the SAMPA digital design are Single Event Upset
(SEU), where a particle can flip a bit in a memory element, and Single Event Transient
(SET) where a single particle creates a transient on a line that can further propagate
to a memory element if the event happens close to a clock edge. Both of these issues
can be recovered from by correcting the data either manually or automatically.
Single Event Latch-up (SEL) issues can also occur, where the particle creates a
temporary short between the supply voltage and ground and which needs to be recovered from by power cycling or lowering the supply voltage. This issue is though layout
related and must be mitigated by altering the layout or by substituting problematic
library components by non-affected components and therefore cannot be directly
mitigated on the design level.
Devices in a radiation environment are also affected by dose-related issues that
alter the analogue properties of a design over time, the more dose that is absorbed. As
the expected dose rates for TPC in Run 3 is only 2.1 k rad [21], this is not considered
an issue, as at this level, without considering annealing, the change in analogue
parameters will be low [22].
Errors induced by SEE can be, for the SAMPA, classified according to three
severity levels: data-path errors, configuration errors, and functional errors. Datapath errors are the least severe errors as the errors occur in parts of the circuitry
that are periodically overwritten. The errors are commonly confined to within one
event. Configuration errors are errors that occur in the configuration registers or
pedestal memory and which will alter the operation of the device. These errors will
remain until the device is reset or reconfigured, and so these errors are of a more
severe character. It is, however, possible for the device to operate normally with these
errors, depending on which configurations changed. Functional errors are the most
severe as they can prevent the device from operating properly. These errors might
happen in the state machines, the memory pointers or in certain counters. In the
SAMPA, all parts of the design are protected against SEE, except for the sections
that are part of the data-path and test structures.
Further information on the radiation tolerance and susceptibility of the device can
be found in [23].