@article{SchrapeAndjelkovicBreitenreiteretal.2021,
  author    = {Schrape, Oliver and Andjelkovic, Marko and Breitenreiter, Anselm and Zeidler, Steffen and Balashov, Alexey and Krstić, Miloš},
  title     = {Design and evaluation of radiation-hardened standard cell flip-flops},
  series = {IEEE transactions on circuits and systems : a publication of the IEEE Circuits and Systems Society: 1, Regular papers},
  volume    = {68},
  journal   = {IEEE transactions on circuits and systems : a publication of the IEEE Circuits and Systems Society: 1, Regular papers},
  number    = {11},
  publisher = {Inst. of Electr. and Electronics Engineers},
  address   = {New York, NY},
  issn      = {1549-8328},
  doi       = {10.1109/TCSI.2021.3109080},
  pages     = {4796 -- 4809},
  year      = {2021},
  abstract  = {Use of a standard non-rad-hard digital cell library in the rad-hard design can be a cost-effective solution for space applications. In this paper we demonstrate how a standard non-rad-hard flip-flop, as one of the most vulnerable digital cells, can be converted into a rad-hard flip-flop without modifying its internal structure. We present five variants of a Triple Modular Redundancy (TMR) flip-flop: baseline TMR flip-flop, latch-based TMR flip-flop, True-Single Phase Clock (TSPC) TMR flip-flop, scannable TMR flip-flop and self-correcting TMR flipflop. For all variants, the multi-bit upsets have been addressed by applying special placement constraints, while the Single Event Transient (SET) mitigation was achieved through the usage of customized SET filters and selection of optimal inverter sizes for the clock and reset trees. The proposed flip-flop variants feature differing performance, thus enabling to choose the optimal solution for every sensitive node in the circuit, according to the predefined design constraints. Several flip-flop designs have been validated on IHP's 130nm BiCMOS process, by irradiation of custom-designed shift registers. It has been shown that the proposed TMR flip-flops are robust to soft errors with a threshold Linear Energy Transfer (LET) from (32.4 MeV.cm(2)/mg) to (62.5 MeV.cm(2)/mg), depending on the variant.},
  language  = {en}
}
@article{BreitenreiterAndjelkovićSchrapeetal.2022,
  author    = {Breitenreiter, Anselm and Andjelković, Marko and Schrape, Oliver and Krstić, Miloš},
  title     = {Fast error propagation probability estimates by answer set programming and approximate model counting},
  series = {IEEE Access},
  volume    = {10},
  journal   = {IEEE Access},
  publisher = {Inst. of Electr. and Electronics Engineers},
  address   = {Piscataway},
  issn      = {2169-3536},
  doi       = {10.1109/ACCESS.2022.3174564},
  pages     = {51814 -- 51825},
  year      = {2022},
  abstract  = {We present a method employing Answer Set Programming in combination with Approximate Model Counting for fast and accurate calculation of error propagation probabilities in digital circuits. By an efficient problem encoding, we achieve an input data format similar to a Verilog netlist so that extensive preprocessing is avoided. By a tight interconnection of our application with the underlying solver, we avoid iterating over fault sites and reduce calls to the solver. Several circuits were analyzed with varying numbers of considered cycles and different degrees of approximation. Our experiments show, that the runtime can be reduced by approximation by a factor of 91, whereas the error compared to the exact result is below 1\%.},
  language  = {en}
}
@article{AndjelkovićChenSimevskietal.2021,
  author    = {Andjelković, Marko and Chen, Junchao and Simevski, Aleksandar and Schrape, Oliver and Krstić, Miloš and Kraemer, Rolf},
  title     = {Monitoring of particle count rate and LET variations with pulse stretching inverters},
  series = {IEEE transactions on nuclear science : a publication of the IEEE Nuclear and Plasma Sciences Society},
  volume    = {68},
  journal   = {IEEE transactions on nuclear science : a publication of the IEEE Nuclear and Plasma Sciences Society},
  number    = {8},
  publisher = {Institute of Electrical and Electronics Engineers},
  address   = {New York, NY},
  issn      = {0018-9499},
  doi       = {10.1109/TNS.2021.3076400},
  pages     = {1772 -- 1781},
  year      = {2021},
  abstract  = {This study investigates the use of pulse stretching (skew-sized) inverters for monitoring the variation of count rate and linear energy transfer (LET) of energetic particles. The basic particle detector is a cascade of two pulse stretching inverters, and the required sensing area is obtained by connecting up to 12 two-inverter cells in parallel and employing the required number of parallel arrays. The incident particles are detected as single-event transients (SETs), whereby the SET count rate denotes the particle count rate, while the SET pulsewidth distribution depicts the LET variations. The advantage of the proposed solution is the possibility to sense the LET variations using fully digital processing logic. SPICE simulations conducted on IHP's 130-nm CMOS technology have shown that the SET pulsewidth varies by approximately 550 ps over the LET range from 1 to 100 MeV center dot cm(2) center dot mg(-1). The proposed detector is intended for triggering the fault-tolerant mechanisms within a self-adaptive multiprocessing system employed in space. It can be implemented as a standalone detector or integrated in the same chip with the target system.},
  language  = {en}
}
@article{AndjelkovicSimevskiChenetal.2022,
  author    = {Andjelkovic, Marko and Simevski, Aleksandar and Chen, Junchao and Schrape, Oliver and Stamenkovic, Zoran and Krstić, Miloš and Ilic, Stefan and Ristic, Goran and Jaksic, Aleksandar and Vasovic, Nikola and Duane, Russell and Palma, Alberto J. and Lallena, Antonio M. and Carvajal, Miguel A.},
  title     = {A design concept for radiation hardened RADFET readout system for space applications},
  series = {Microprocessors and microsystems},
  volume    = {90},
  journal   = {Microprocessors and microsystems},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0141-9331},
  doi       = {10.1016/j.micpro.2022.104486},
  pages     = {18},
  year      = {2022},
  abstract  = {Instruments for measuring the absorbed dose and dose rate under radiation exposure, known as radiation dosimeters, are indispensable in space missions. They are composed of radiation sensors that generate current or voltage response when exposed to ionizing radiation, and processing electronics for computing the absorbed dose and dose rate. Among a wide range of existing radiation sensors, the Radiation Sensitive Field Effect Transistors (RADFETs) have unique advantages for absorbed dose measurement, and a proven record of successful exploitation in space missions. It has been shown that the RADFETs may be also used for the dose rate monitoring. In that regard, we propose a unique design concept that supports the simultaneous operation of a single RADFET as absorbed dose and dose rate monitor. This enables to reduce the cost of implementation, since the need for other types of radiation sensors can be minimized or eliminated. For processing the RADFET's response we propose a readout system composed of analog signal conditioner (ASC) and a self-adaptive multiprocessing system-on-chip (MPSoC). The soft error rate of MPSoC is monitored in real time with embedded sensors, allowing the autonomous switching between three operating modes (high-performance, de-stress and fault-tolerant), according to the application requirements and radiation conditions.},
  language  = {en}
}