High-speed wide dynamic range linear mode time-of-flight receiver based on zero-crossing timing detection

Abstract

We present an accurate laser radar receiver with a wide dynamic range intended for ranging applications based on an event-based approach, in which a receiver-time-to-digital converter is used to extract the timing information from the reflected echo. The receiver is based on LC resonance pulse shaping at the input so that the unipolar pulse detected by the avalanche photodiode is converted to a bipolar signal, and the first zero-crossing of this converted signal is marked as the only timing point. One important aspect of the proposed scheme is that it does not need any postcompensation or gain control for achieving a wide dynamic range. The receiver chip was fabricated in a 0.35-μm standard CMOS technology, and a laser radar platform was developed to verify the functionality of the proposed receiver channel. The measured accuracy of the receiver is AE3.5 cm within a dynamic range of more than 1:250,000 using 3-ns FWHM pulses when target materials with different reflectivities are used in the measurements. The single-shot precision of the receiver (σ value) is ∼5 cm for a minimum SNR of ∼10. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Improving the Accuracy of TOF LiDAR Based on Balanced Detection Method

“…where 𝑖 is the signal current and the denominator of the equation corresponds to various The different components of photocurrent I d1 and I d2 in two channels flow into the transimpedance amplifier, which then becomes the output bipolar voltage signal. Walk error caused by variation in echo pulse amplitude during ranging can be as large as several nanoseconds [16], as shown in Figure 2b. The BDM takes the zero-crossing point of the bipolar signal as the timing moment, shown in Figure 2c, which can keep the walk error at a low level.…”

“…However, it requires to be calibrated and calculated separately, which increases the complexity of the lidar signal processing system and reduces its processing speed [13][14][15]. Another approach to reduce the walk error is to complete the shaping of the unipolar to bipolar pulses at the receiver input through an LC resonator, where the first zero-crossing point is used as the timing marker [16].…”

Generalized-Mode Averaging Technique for Wrapped Phase

“…Later, Kim et al proposed, based on previous geometric unwrapping [12], that random noise can be removed by circular averaging as long as the wrapped phases satisfy the von Mises distribution. Additionally, when processing the wrapped phase in an interferogram, self-mixing interferometry is a good option, as the interferometric fringe is in a distorted sinusoidal pattern [13][14][15]. For random noise, regardless of whether it conforms to a uniform or Gaussian distribution, its mean is 0.…”