The world of electronics seems doomed to undergo a change on a scale comparable to that which occurred just over seventy years ago, when transistors broke in to end the reign of vacuum tubes. Semiconductor manufacturers are finding it increasingly difficult to continue to improve their manufacturing technology because each step they take brings them closer to the physical limit imposed by silicon. But, fortunately, it seems that we are touching the solution to this problem with our fingertips.
Sungsik Lee, a professor of electronic engineering at the National University of Pusan, in South Korea, and a former researcher at the University of Cambridge, in the United Kingdom, has published research in which he theoretically describes a new type of device electronic capable of carrying out the inverse function of a transistor.
But what is really interesting is that in his study he argues that these “inverse transistors” will allow us to manufacture simpler, faster integrated circuits with lower consumption, which is why it is postulated as the technology that could prevent semiconductor stagnation. So much so that in his article, which has been published in the IEEE journal and has been echoed in the MIT magazine and the Cornell University repository (United States), Lee speaks of a “new paradigm” of the world of The electronic.
What is a reverse transistor and what does this technology promise us?
Before we see what a reverse transistor is, it is good for us to review what a conventional transistor is. Currently we can find these tiny elements in practically any integrated circuit that we can imagine: microprocessors, power amplifiers, switches, rectifiers, oscillators … And this in practice means that they reside inside our computers, smartphones, tablets, stereos, televisions, radios, cars, medical equipment and a host of other devices.
Although their precursors are even older, the first transistors as we know them today were invented in 1947 by John Bardeen, William Shockley, and Walter Brattain, three physicists at Bell Laboratories. A simple way to define a transistor invites us to describe it as a semiconductor electronic device that is capable of responding to an input signal by giving us a specific output. An electronic amplifier, for example, will increase the power, voltage or current of the signal that we place at its input at its output, resorting, of course, to an external power source.
The first transistors were invented in 1947 by John Bardeen, William Shockley, and Walter Brattain, three physicists at Bell Laboratories.
There are several types of transistors (bipolar, point contact, field effect, union, single electron, phototransistors, organic electrochemicals, etc.), but fortunately, we do not need to delve into them to understand what reverse transistors are, which is what really interests us in this article. It is enough for us to know two more facts about transistors. On the one hand, they are active elements within integrated circuits. And, furthermore, those that have allowed us to reach the level of integration used by current lithographic techniques are field effect (FET).
Unlike capacitors, coils or resistors, which are passive elements, transistors are active components of a circuit because they either exert a control function over its behavior, or they introduce a certain gain because they act in a non-functional way. linear. This means that the relationship between the applied voltage and the current demanded by the circuit cannot be expressed using a constant value, which introduces a complexity that is not present in linear systems.
However, the behavior of capacitors, resistors and coils, which, as we have seen, are passive elements in an electrical circuit, is clearly delimited and linear. In addition, they facilitate the connection of the active components and make possible the transfer of the electrical signal by means of storage in magnetic or electrical fields, or by means of the dissipation of electrical energy.
Capacitors, coils, and resistors are passive elements of an electrical circuit, while transistors are active elements.
On the other hand, about field effect transistors (FETs) we are interested in knowing, without going into complex details, that they use the electric field to let or not the current pass through a channel that carries a single type of electric charge. This type of transistors is what has made possible the integrated circuits that we currently use in our digital systems.
During the last decades many researchers have made an effort to study the characteristics of the passive elements of electrical circuits with the intention of finding out if there are other components with different properties that can replace or complement them. Sungsik Lee, however, has undertaken a similar task, but with the active components. With transistors. And the result of his investigation is the ‘trancitors’.
The word ‘transistor’ describes quite precisely what one of these elements does: it takes an input signal and carries current or not at the output. We can imagine it as something like a resistor with variable capacity. In fact, the word ‘transistor’ comes from the English terms transfer (transfer) and resistor (resistance). What Lee has described is a device with characteristics similar to those of transistors, but, unlike these, capable of taking an input signal and carrying or not carrying voltage at the output. It is somewhat similar to a hypothetical capacitor with a variable energy storage capacity.
The term that Lee proposes to identify the element he has devised is ‘trancitor’ because its properties, as with the word ‘transistor’, can be condensed from the English terms transfer (transfer) and capacitor (capacitor). ). However, we should not think of ‘trancitors’ as active elements designed to replace transistors, but rather as devices designed to coexist with them in the same circuit.
What sense then does it make to use even more elements in our integrated circuits? It seems logical to think that introducing the ‘trancitors’ without eliminating the transistors will increase the complexity, consumption and size of integrated circuits. However, Lee assures that this is not the case because the introduction of ‘transitors’ entails the use of a smaller number of transistors. That is, according to this researcher, the key.