A Novel Compact Current Driver Circuit with Temperature Feedback Control for 2D Nanophotonic Phased Arrays

This paper presents a compact driver circuit with independent pixel-level temperature regulation for thermo-optic based 2D Nanophotonic phased arrays (NPAs) in light detection and ranging (LIDAR) and Virtual Reality (VR) applications. To minimize the interconnection density, the proposed driver unit uses only a single electrical contact to its corresponding NPA pixel for both heating and temperature measurement functions. The driver was fabricated using TSMC 65 nm technology and each unit is realized in an area of $15\ \mu\mathrm{m}\times 15\ \mu\mathrm{m}$. The design enables scalable 3D heterogeneous integration between any tile-based NPA with pixel pitch below $15\ \mu\mathrm{m}$ and its electrical control system. The temperature regulation performance of the proposed circuit was characterized by intentionally introducing a ±20% variation to the load resistance to simulate the temperature deviation in the NPA. The measured phase errors are suppressed by the feedback controller to a maximum of $0.07\pi$ and an average of $0.02\pi$ within the full $2\pi$ phase shift operation range.