A research team led by Prof. Junghyup Lee of the Department of Electrical Engineering and Computer Science at DGIST has become the first in the world to develop a “time-interleaved noise-shaping SAR ADC (analog-to-digital converter)” semiconductor chip capable of simultaneously measuring multiple biosignals, including electrocardiograms (ECG) and electromyograms (EMG). The team developed this technology in an actual semiconductor chip and successfully completed functional validation. Their findings were presented at the IEEE Symposium on VLSI Technology & Circuits (VLSI 2026), held in Honolulu, June 14–18.
Accurately measuring multiple biosignals using wearable devices such as smartwatches requires meeting several demanding conditions. These include “ultra-high input impedance (resistance)” to prevent signal loss even when no sweat is present on the skin or when contact is loose (dry or non-contact electrodes), a “wide input range” to prevent signal distortion caused by vigorous movement, and “ultra-low power consumption” for long-term operation. However, conventional measurement approaches have struggled to satisfy all these requirements simultaneously within a single chip.
Lee’s research team addressed this challenge by proposing a novel “time-interleaved third-order noise-shaping SAR ADC” architecture in which circuit blocks that consume significant power and chip area are shared across multiple channels, while only essential components (the residual capacitor banks) are allocated separately to each channel. This approach dramatically reduced the circuit area and power consumption required for multichannel systems, enabling an ultra-compact, ultra-low-power chip.
