LIDAR Pixel Processing Circuit Using Coarse Histogram Bins
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Solution Overview
Problem
Time-of-flight LIDAR systems face challenges in reducing power consumption and data rates due to the high power consumption of Time-to-Digital Converter (TDC) circuits and the generation of large amounts of data, making it difficult to implement larger arrays efficiently.
Innovation Solution
A Light Detection and Ranging (LIDAR) measurement circuit using an array of single photon detectors and a pixel processing circuit that calculates the estimated time of arrival of photons using coarse histogram bins, eliminating the need for TDCs by employing a Center of Mass Method (CMM) and edge sampling, and storing data in static random access memory (SRAM).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TDC circuits are used to timestamp incident photons, then timing resolution is improved, but power consumption increases and data rates become unfeasibly large
Solution Approach 1:
The patent extracts only the essential timing information needed for depth calculation, discarding the detailed timestamp data that TDCs generate. Instead of recording precise timestamps for each photon, the system uses coarse histogram bins to accumulate photon counts in time intervals, extracting only the necessary temporal distribution information while eliminating excessive data generation and associated power consumption.
Solution Approach 2:
The patent inverts the conventional approach by not trying to reduce coarse histogram data to precise timestamps, but rather using coarse histogram bins directly for depth calculation. Instead of fine-to-coarse conversion, the system performs coarse-to-fine calculation by computing depth estimates directly from the histogram bin distributions using center-of-mass algorithms, achieving accurate depth measurement without TDC-level precision requirements.
2Measurement precision
If TDC circuits are used to timestamp incident photons, then timing resolution is improved, but device complexity increases
Solution Approach 1:
The patent removes the complex TDC circuitry entirely from each pixel, extracting only the necessary timing measurement function through simpler histogramming circuits. By eliminating TDCs and using basic counter-based histogram accumulation in coarse bins, the system achieves adequate timing resolution for depth measurement while dramatically reducing circuit complexity and area per pixel.
Solution Approach 2:
The patent replaces expensive, complex TDC circuits with simple, low-cost histogram bin counters that can be implemented using basic digital logic. These simpler counting circuits consume less area and power, enabling larger sensor arrays while maintaining functional equivalence for depth measurement applications.
3Measurement precision
If TDC circuits are used to timestamp incident photons, then timing resolution is improved, but data generation becomes unfeasibly large
Solution Approach 1:
The patent extracts only the essential temporal distribution information needed for depth calculation, discarding the excessive timestamp data that TDCs generate. By accumulating photons in coarse histogram bins rather than recording individual timestamps, the system reduces data volume from millions of 10-16 bit timestamps per second to manageable histogram count distributions, enabling practical data processing and transmission.
Solution Approach 2:
The patent inverts the data processing approach by not attempting to convert coarse histogram data into precise timestamps, but rather using the histogram bin distributions directly for depth estimation. This inversion eliminates the need for complex timestamp reconstruction algorithms and reduces data processing requirements while maintaining accurate depth measurement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces power consumption and data rates by integrating multiple timestamps in a computationally and power-efficient manner, allowing for larger arrays to be implemented while maintaining accurate time-of-flight measurements.
Implementation Method 1
The initiating charge carrier can be photo-electrically generated by means of a single incident photon striking the high field region
Data Source
AI summary
A Light Detection and Ranging (LIDAR) measurement circuit includes an array of single photon detectors configured to detect photons responsive to emission of an optical signal from an emitter, and a pixel processing circuit that is configured to calculate an estimated time of arrival of photons incident on the array of single photon detectors by utilizing a plurality of coarse histogram bins. Respective ones of the plurality of coarse histogram bins are associated with a duration that is greater than one-sixteenth of a pulse width of the optical signal.