Development of Next-Generation Semiconductor Devices Applying 'Much Faster' Ternary System

Published 11 Jul.2023 14:15(KST)

KAIST-Gachon University Joint Research Team

Conventional computers use binary logic circuits based on 0 and 1. However, as technologies requiring complex calculations such as autonomous driving and artificial intelligence (AI) become commonplace, there is a growing demand for alternatives that can process data faster and in larger volumes. A domestic research team has attracted attention by developing next-generation semiconductor technology applying ternary logic instead of binary.

Schematic diagram of the next-generation semiconductor applying the newly developed ternary digital logic circuit by the research team. Image source: KAIST

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 11th that Professor Seong-Gap Lim’s research team from the Department of Biological and Chemical Engineering, in collaboration with Professor Ho-Cheon Yoo’s team from Gachon University, has succeeded for the first time in the world in implementing a novel digital logic circuit that offers higher data processing efficiency and integration density.

Compared to binary logic circuits that use two logic states, 0 and 1, ternary logic circuits use three logic states, 0, 1, and 2, to represent information, making it a next-generation semiconductor technology. Since the same information can be expressed with fewer logic states, it enables faster, lower-power, and smaller semiconductor chips through higher information processing efficiency. However, the addition of one more logic state makes it difficult to stably output all three logic signals, and the incompatibility between binary and ternary logic systems has been considered an obstacle to the commercialization of ternary logic circuits.

To solve these problems, the research team developed a new logic device capable of adjusting the output characteristics of ternary logic circuits in real time during circuit operation. They focused on flash memory, a device in computers that can store or erase information as needed. By integrating flash memory into the logic devices that make up the ternary logic circuit, they enabled the circuit itself to store information. The team confirmed that the output characteristics of logic state 1 can be systematically adjusted depending on the information stored in the ternary logic circuit. Through this, they succeeded in achieving world-class operational stability (noise margin) of about 60% for ternary logic circuits.

Additionally, the research team utilized the fact that when the information stored in the ternary logic circuit is completely erased, logic state ‘1’ is not output, and only the two logic states ‘0’ and ‘2’ are output, to successfully implement a circuit capable of operating in both binary and ternary logic modes. Furthermore, by storing different information in each logic device constituting the logic circuit, they combined binary and ternary logic outputs. As a result, they confirmed that it is possible to further improve the information processing efficiency and integration density of ternary logic circuits by implementing logic circuits with various types of logic outputs.

The logic device developed by the research team is significant in that it enables data and signal transmission by linking binary and ternary logic circuits within the same semiconductor chip. This means that the existing binary system can be maintained while flexibly utilizing the high information processing capability of ternary logic as needed, and it is expected to become a core technology at the initial stage of commercialization of ternary semiconductors in the future.