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The Journal of Semiconductor Technology and Science (JSTS) is an international, peer-reviewed, and open-access journal that is published bimonthly.
- Scope: semiconductor processes, devices, circuits, and MEMS.
- Editor-in-Chief: Prof. Woo Young Choi (ECE, Seoul National University)
- Indexed within Science Citation Index Expanded (SCIE), SCOPUS, Korea Citation Index (KCI), and other databases.

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Title A 32-Channel 8-bit DAC-based Driver IC with Channel Uniformity Optimization for Optical Phased Arrays
Authors (Kihun Kim) ; (Woo-Young Choi)
DOI https://doi.org/10.5573/JSTS.2025.25.5.542
Page pp.542-547
ISSN 1598-1657
Keywords Light detection and ranging (LiDAR); optical phased array (OPA) driver IC; digital-to-analog converter (DAC); differential nonlinearity (DNL); integral nonlinearity (INL); process robustness
Abstract Light detection and ranging (LiDAR) technology, which leverages light instead of radio waves as the source, offers superior resolution and resistance to jamming, making it a promising alternative to radio detection and ranging (RADAR) for 3D imaging and object detection. Silicon photonics-based optical phased arrays (OPAs) enable non-mechanical beam steering, overcoming the limitations of traditional rotating LiDAR systems. In OPAs, optical phase shifts are realized with the driver IC, which provides the necessary analog voltages to the optical phase shifters. This paper presents a 32-channel OPA driver IC designed to achieve high linearity and enhanced channel-to-channel uniformity. The proposed IC integrates an 8-bit digital-to-analog converter (DAC) based on an R-2R ladder, a high-gain rail-to-rail amplifier, and an I2C serial interface to support scalable multi-chip operation up to 128 channels. Key design strategies include layout optimization of resistors and MOSFETs within the driver to reduce mismatch and improve channel consistency under process variations. Fabricated in a 180 nm CMOS process, the proposed IC delivers monotonic DAC operation with a worst-case differential nonlinearity (DNL), which quantifies the deviation in step size between adjacent codes, of 0.52 least significant bits (LSB), and an integral nonlinearity (INL), which measures the deviation of the DAC transfer function from an ideal straight line, of 0.81 LSB, validating its process-robust design. Beamforming simulations using measured DAC performance demonstrate minimal performance degradation, with less than 0.2% main lobe intensity loss and negligible side lobe suppression ratio degradation. These results confirm that the proposed driver IC is suitable for robust and scalable OPA-based LiDAR systems.