LiDAR (Light Detection and Ranging) sensors have become important for depth sensing in applications like augmented reality, autonomous vehicles, and surveillance. Among different LiDAR approaches, direct time-of-flight (dToF) is advantageous because of its immunity to multi-path interference and ease of integration with vision systems. However, designing a dToF system that balances power efficiency, ambient light tolerance, range, and resolution is challenging. Increasing laser power or reducing histogram bin size often improves performance but also increases power consumption and memory requirements.
In this work, the authors propose a dToF LiDAR system optimized for mobile applications. The system uses a 940nm scanning laser source and a 192×144 single-photon avalanche diode (SPAD) array receiver with on-chip histogramming. A key feature is an adaptive single-pass histogram architecture that operates in coarse resolution mode when returned signals are weak, saving power. Novel signal processing methods, including pulse collision recovery and conditional peak enhancement filtering, help improve range resolution beyond the coarse histogram bin size. Simulations of the system demonstrate 1% range accuracy up to 10 meters, 30 frames per second operation, and only 12mW optical power consumption.
The adaptive single-pass histogramming provides superior performance compared to two-pass approaches under limited optical power budgets. By recovering signals lost to pulse collisions and accurately enhancing peaks, the processing methods help maximize range resolution. The system strikes a good balance of power efficiency, ambient light tolerance, range, and resolution. According to the simulation results, the system is well-suited for mobile depth sensing applications requiring low power consumption.
Keywords: LiDAR, SPAD, dToF
Figure 1.This work proposes a LiDAR system with a 940nm infrared transmitter (TX) and addressable SPAD array receiver (RX).
Figure 5.Sensor chip (RX) architecture.