Saeed Ahmed
Specialists of the National Research Nuclear University “MEPhI” and the Research Institute for System Studies of the Russian Academy of Sciences have developed elements for the design of asynchronous microcircuits that are resistant to malfunctions and are especially effective in work on space vehicles, the press service of the NNIU MEPhI reported.
Microcircuits used in conventional technology, such as cars or computers, are poorly suited for space vehicles because of their low reliability under conditions of cosmic radiation. High-energy ions in space provoke device errors and accidents. Therefore, the development of ASIC (integrated circuit for special purposes) for space vehicles requires special methods to increase fault tolerance (speaking the common language, reliability).
The specificity of synchronous microcircuits is that their complexity – as well as the number of elements on the chip of the circuit – is constantly growing, the sections of such circuits separated by a large distance must be synchronized at the clock frequency (the number of clock cycles per second). the signal from the clock frequency generator does not come at regular intervals, the circuit simply stops working, “said Maxim Gorbunov, assistant professor at the NNIU MEPhI.
According to the scientist, this is a rather complex engineering problem, coupled with a deterioration in the characteristics of the chip. Therefore, today asynchronous schemes are promising, which, unlike synchronous ones, do not require clock synchronization.
“Switching bits in an asynchronous device goes in parallel and without delay: it makes it more efficient and energy-intensive than a synchronous counterpart.The data reaches the processing unit as fast as the data path in the processor allows, and is processed when the corresponding chip blocks are ready do it, “- explained Gorbunov
With the methodology of constructing such schemes, things are more complicated – there is no standard route for their design. Despite the fact that the logic of constructing asynchronous microcircuits was proposed back in the 70’s. XX century – the main direction remains working with synchronous schemes.
“Technological capabilities of synchronous microcircuits have reached the limit: even now the design standards (the minimum chip element size) have become less than 10 nanometers, and at the same rates, asynchronous circuits can work faster than synchronous circuits, since they do not require synchronization of different parts of the crystal,” the expert said.
That’s why Russian scientists decided to offer new elements for reliable and fast asynchronous microcircuits. Their article in the scientific journal “Acta Astronautica” is devoted to Muller’s fault-tolerant C-elements – the basic logic gates used in the design of asynchronous circuits.
The C-element is a logical device with a built-in memory element. In fact, this is a building block with two inputs, in case of coincidence of which the signal is transmitted further (and in case of a mismatch, the element stores the previous value).
“Using the well-known in synchronous logic way of DICE (Dual Interlocked Cell) to the three variants of the circuit implementation of the C-element, we have received 3 new DICE C-element schemes with increased fault tolerance,” – said another author, head of the topology sector of radiation-resistant VLSI FGU FNTS NIISI RAS Igor Danilov.
According to scientists, the developed circuits can be used in the design of asynchronous microcircuits, which are more fault-tolerant and designed for use in the latest space technology.
