Shielding the chips by using depleted boron: The depleted boron consists only of isotope boron Cosmic radiation will produce secondary neutrons if it hits spacecraft structures; and neutrons cause fission in Boron if it is present in the spacecraft's semiconductors, producing a gamma ray, an alpha particle and a lithium ion. The resultant fission products may then dump charge into nearby semiconductor chip structures, causing data loss bit flipping, or single event upset.
In radiation hardened semiconductor designs, one countermeasure is to use depleted boron which is greatly enriched in Boron and contains almost no Boron Boron is largely immune to radiation damage and it is a by-product of the nuclear industry. In general, the depleted boron is used in the borophosilicate glass passivation layer to protect the chips.
Here, borophosphosilicate glass, commonly known as BPSG, is a type of silicate glass that includes additives of both boron and phosphorus Kern and Smeltzer, Logical radiation-hardening techniques adopt various logical means, such as using error correcting memory, utilizing redundant elements, adopting a watchdog timer etc.
Finally, the reliability evaluation problem is introduced. Error correcting memory: In general, DRAM memory can afford increased protection against soft errors based on error correcting codes.
The error-correcting memory, known as ECC Error Correcting Codes or EDAC Error Detection and Correction -protected memory, is especially suitable for high fault-tolerant applications, such as servers, as well as deep-space applications due to cosmic radiation. It utilizes extra parity bits to check for and possibly correct corrupted data. Since, radiation effects may destroy the memory content even if the system is not accessing the RAM, a so-called scrubber circuit should be used to continuously sweep the RAM. Typically, the following three steps are involved:.
Traditional error-correcting memory controllers adopt Hamming codes, although, some may use triple modular redundancy TMD.
Overview of Radiation Hardening Techniques for IC Design
Interleaving allows us to distribute the effect of a single cosmic ray that potentially upsets multiple physically neighboring bits over multiple words by associating neighboring bits to different words. As long as a Single Event Upset SEU is not larger than the error threshold in any particular word between accesses, it can be corrected and the illusion of an error-free memory system can be maintained. However, state-of-the-art CMOS and disk technologies have very small error rates that may be only in order of one in a billion and thus rigorous error correction is not always necessary.
Recently, Jeffery et al. For high error rates, however, stronger and multiple error correcting codes such as BCH codes are required for nano-scale devices Sun and Zhang, Ou and Yang proposed hardware design for the decoding and encoding routines of Hamming codes, where the memory reliability is increased at the cost of only 5ns delay in the memory access time.
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Although, Hamming codes are capable of correcting a single error in the block of physical bits used in the encoding, they become less productive for high error rates. In practical applications, the BCH , 32, 45 code can provide In general, if we only use error correcting codes, we will need very strong and complex error correction codes resulting in large overhead in area and latency and thus we will lose all the benefits of using nanoscale memory. According to above description, besides active error correction through encoding, we require using defect maps to store the locations of the faulty bits in memory devices Vollrath et al.
radiation-hardened soi transistor: Topics by indotnale.tk
For reconfigurable architectures, tile-based memory units have been proposed by storing the defect map in a distributed fashion He et al. However, the drawback of using defect maps in the bit-level lies in that the storage overhead is generally very high. To reduce the size of the required defect map, Tahoori proposed a defect unaware design flow Tahoori, that identifies universal defect free subsets within the partially defective chips, while Wang et al. However, hashing for every bit is computationally expensive and may significantly increase the number of memory access times.
Therefore, Sun and Zhang proposed the use of CMOS memory for storing metadata to identify good parts of the memory based on two schemes:.
We should note that the amount of memory to store the ranges increases with the sparseness of faulty memory bits. In a word, error correcting codes reduce the defect rate of memory at the cost of additional computation and redundancy. For example, strong error correcting codes e. The encoding and decoding delay is very high.
Redundant elements: In engineering, redundancy is the duplication of critical components of a system so as to enhance system reliability, typically in the case of a backup or fail-safe. In many safety-critical systems, e. An error in one component can then be out-voted by the other two. In a triply redundant system, its three sub components must fail before the system fails. Since, each one seldom fails and is expected to fail independently, the probability that all three fail is calculated to be extremely small.
Redundancy is also known as the term majority voting systems Srihari, or voting logic. More generally, there are four major forms of redundancy as follows:. Redundant elements can be used at the system level or the circuit level. At the system level, three separate microprocessor boards may independently compute an answer to a calculation and compare their answers. Any system that produces a minority result will recalculate. Logic may be added to shut down the board occurring repeated errors. At the circuit level, a single bit may be replaced with three bits and separate voting logic for each bit to continuously determine its result.
However, this strategy will increase the area of a chip design by a factor of 5, so it must be reserved for smaller designs. But it has the secondary advantage that it is also fail-safe in real time.
In the event of a single-bit failure, the voting logic will continue to produce the correct result without resorting to a watchdog timer. System-level voting between three separate processor systems will generally need to use some circuit-level voting logic to perform the votes between the three processor systems. Recently, Nepal et al.
Myers and Rauzy studied the assessment of the reliability of redundant systems with imperfect fault coverage. They termed fault coverage as the ability of a system to isolate and correctly accommodate failures of redundant elements. For highly reliable systems, such as avionic and space systems, fault coverage is in general imperfect and has a significant impact on system reliability. They reviewed different models of imperfect fault coverage and proposed efficient algorithms to assess them separately. Gonzalez and Mazumder presented a survey of circuit implementations of redundant arithmetic algorithms in three main groups:.
For each of the circuits, the operating principle was described and the main advantages and disadvantages of the approach were discussed and compared. Watchdog timers: A watchdog timer can be employed to perform a hard reset of a system unless some sequence is performed that generally indicates the system is alive, such as a write operation from an onboard processor.
During normal operations, software schedules a write to the watchdog timer at regular intervals to prevent the timer from running out. If the radiation causes the processor to operate incorrectly, it is unlikely that the software will work correctly enough to clear the watchdog timer. The watchdog eventually times out and forces a hard reset to the system. This is considered as a last resort to other methods of radiation hardening. Recently, El-Attar and Fahmy studied the ability of different watchdog timer systems to recover the system from failure and a new improved watchdog timer system design was introduced.
They first introduced standard watchdog timers and windowed watchdog timers and then proposed their sequenced watchdog timers. A standard watchdog timer in its simplest form is a monostable timer. When the timer reaches its maximum value it changes its logical state. The system must reset the timer before it reaches maturity. If the system fails to reset the timer an action is taken whether to change the state of an output or to immediately restart the system.
In order to solve the problem of fast watchdog resets, the windowed watchdog timer adopt a new supervisory system based on two timers instead of one. The first Timer has a timeout of T1 and the second timer has a timeout of T3. The sequenced watchdog timer is an improved design of the windowed watchdog timer. It requires minor modifications to the ClearDWT instruction. The ClearDWT instruction is originally an inherent, which means it does not require and operand to be executed. The instruction is modified to include an operand.
Once the Opcode is Fetched and decoded, the control unit resets the Windowed watchdog timer. If a slow or fast resets occur the watchdog immediately resets the system.
www.hiphopenation.com/mu-plugins/tobias/jyjos-dating-fattorini.php If the ClearDWT opcode is executed within the safe window then the operand is compared to the value of the sequenced timer register. If the value matches, then the system is operating properly. If the value does not match then a faulty reset occurred within the safe window of the watchdog timer. The sequenced watchdog timer then resets the whole system. Reliability evaluation: It should be noticed that, in addition to above hardening techniques, how to test the reliability of the integrated circuit is also a very important topic.
Besides, we investigated the effect of accelerated factors on MMICs degradation and make a comparison between the Weibull and lognormal distributions. Background: An amplifier is one of the most common electrical elements in any circuit system. The requirements for amplification are as varied as the systems where they are applied.
Amplifiers are available in various forms ranging from minuscule ICs to the largest high-power transmitter amplifiers. An RF power amplifier Grebennikov, is a sort of electronic amplifier employed to convert a low-power radio-frequency signal into a larger signal with significant power typically in order to drive the antenna of a transmitter. It is usually optimized to have high efficiency, high output power compression, good return loss on the input and output, good gain and optimal heat dissipation. As a high-power device with large gain, it provides large output signal power while requiring very small amount of RF power and it is commonly available from any commercial signal generator.
Therefore, the power amplifier is normally known as the RF source or sometimes the Transmitter. Microwave power amplifiers can be utilized in testing applications ranging from passive elements such as antennas to active devices such as limiter diodes or MMIC based power amplifiers. Furthermore, some other applications include testing requirements where a relatively large amount of RF power is necessary for overcoming system losses to a radiating element, or where there is a system requirement to radiate a Device-Under-Test DUT with an intense electromagnetic field.
As a key link for wireless applications, solid-state active power amplifiers have been widely used in satellite communication, radar, electronic warfare, satellite navigation and weapon guidance systems. Due to the harsh requirements and the complexity of the transmission environment in wireless communication , the design of microwave power amplifiers almost becomes one of the most difficult functional units in the front of an RF transceiver system and its linearity, output power and efficiency greatly affect the signal quality, communication distance and communication time of the wireless communication system.
Among these systems, because of the adverse external environment, aerospace applications not only impose higher more stringent requirements upon the performance of solid-state active power amplifier but also bring greater challenges for its design. All the countries in the world particularly the US and Japan pay much attention to solid-state active power amplification chip design and manufacturing technology and they have developed many new products, such as the entire microwave system integrated in a single chip with a diameter of few centimeters.
This chip has been substituted for the earlier microwave hardware chassis. This new microwave system on chip has greatly improved the performance of microwave systems and promotes the development of communication technology, radar technology and aerospace technology. In , the Department of Defense of USA announced three national defense science and technology strategy files, i. One of the prominent properties of microwave component is small volume and weight.