Event-Driven Time-to-Digital Converter for Low-Power 3D Imaging
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Solution Overview
Problem
Existing 3D imaging systems face high power consumption due to the constant activity of the coarse interpolator in time-to-digital converter (TDC) schemes, particularly in Time to Distance conversions, which is inefficient for long-range applications.
Innovation Solution
A 3D imager with an adjustable reference clock and an event-driven time-to-digital converter system, where the reference clock frequency is adapted based on the estimated time to subsequent photon incidence, and the TDC is activated only upon event detection, reducing power consumption by limiting operation to the relevant time interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference clock frequency is kept high to ensure accurate timing for long-range photon detection, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The reference clock frequency is made dynamically adjustable rather than fixed. The system adapts the clock frequency based on the estimated time to subsequent photon incidence, using higher frequencies only when long-range detection is required and lower frequencies otherwise, thereby reducing average power consumption while maintaining measurement precision when needed
Solution Approach 2:
The system changes the operational parameter (reference clock frequency) based on detection requirements. By adjusting the frequency parameter dynamically according to the estimated photon arrival time, the system optimizes the balance between measurement precision and power consumption
2Productivity
If the coarse interpolator is kept active throughout to count clock cycles, then productivity is improved, but power consumption increases
Solution Approach 1:
Instead of continuous operation, the coarse interpolator is activated periodically or event-driven. The system uses periodic photon detection events to trigger the interpolator activation, keeping it inactive during intervals without detection events, thus maintaining productivity while significantly reducing power consumption
Solution Approach 2:
The system performs preliminary estimation of the time to subsequent photon incidence to predict when the coarse interpolator will be needed. This allows the interpolator to be activated only in advance of expected photon arrivals rather than continuously, optimizing both productivity and power consumption
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 drastically reduces power consumption in 3D imaging systems by optimizing the reference clock frequency and activating the TDC only when necessary, making it suitable for low-power applications like machine vision and security systems.
Implementation Method 1
a photodetector for detecting photon incidence
Implementation Method 2
the reference clock generator is configured for adjusting the frequency of the reference clock on the basis of an estimated time up to a subsequent photon incidence
Data Source
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AI summary
3D imager comprising at least one pixel, each pixel comprising a photodetector for detecting photon incidence and a time-to-digital converter system configured for referencing said photon incidence to a reference clock, the 3D imager further comprising a reference clock generator provided for generating the reference clock, wherein the reference clock generator is configured for automatically adjusting the frequency of the reference clock on the basis of a time up to a subsequent photon incidence as estimated in a first series of measurements.