ToF Signal Processing with Single-Channel Phase Measurement
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Solution Overview
Problem
Existing time of flight measurement technologies require large digital areas and high power consumption due to the need for multiple multipliers and ADC channels to calculate phase differences, limiting their application in portable and mobile devices.
Innovation Solution
A signal processing unit that generates multiple reference phases using an oscillation module, allowing for reduced power consumption by using a single multiplier and ADC channel to calculate phase differences, and enabling smaller die sizes through analog processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four multipliers and ADC channels are used to compute phase in indirect phase type frequency modulation ToF, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines multiple phase measurement operations into a single ADC channel by using a dual-slope integrating ADC that processes both in-phase and quadrature components through time-multiplexed integration. This merging approach eliminates the need for four separate ADC channels and multiple multipliers, reducing digital area while maintaining phase measurement precision through integrated signal processing.
Solution Approach 2:
The patent replaces complex digital signal processing (multiple multipliers and ADC channels) with analog integrating circuits that perform correlation measurements in the analog domain. The dual-slope integrating ADC uses analog integration to compute phase information, substituting digital computation with analog processing to reduce digital area and power consumption.
2Measurement precision
If four multipliers and ADC channels are used to compute phase, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent merges multiple power-consuming digital components (four multipliers and four ADC channels) into a single integrated analog processing path. The dual-slope integrating ADC processes both signal components through one channel, significantly reducing the number of active digital circuits and thereby lowering overall power consumption while preserving measurement precision.
Solution Approach 2:
The patent substitutes power-intensive digital multiplication and conversion operations with lower-power analog integrating circuits. The analog integration process requires minimal digital switching activity, reducing dynamic power consumption compared to running four separate multiplier-ADC chains in the digital domain.
3Adaptability or versatility
If multiple reference phases are generated using PLL or DLL, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal oscillation module that can generate multiple reference phases (including in-phase and quadrature components) using a single PLL or DLL configuration. This multi-functional approach allows the same hardware block to provide all necessary phase references for the integrated ADC, reducing overall device complexity compared to having separate phase generation circuits for each ADC channel.
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 solution reduces power consumption and die size, enabling portable and mobile applications while improving signal-to-noise ratio and allowing for scalable performance and cost-effective manufacturing.
Implementation Method 1
The oscillation module may further comprise a Phase Locked Loop (PLL) or Delay (Line) Locked Loop (DLL) to generate m−1 further reference signals based on the reference signal generated by the oscillator
Implementation Method 2
the oscillation module may comprise an oscillator, e.g., a crystal oscillator, an internal RC relaxation oscillator or a similar entity that allows for generation of a reference signal with predetermined frequency and phase
Implementation Method 3
The transmission module may comprise a light source such as a emitting diode (LED) or a vertical-cavity surface emitting laser (VCSEL) for generating pulsed light
Implementation Method 4
The transmission module may comprise a light source such as a emitting diode (LED) or a vertical-cavity surface emitting laser (VCSEL) for generating pulsed light
Implementation Method 5
The detection module may comprise a photo diode or the like in order to generate the electrical detector signal
Data Source
AI summary
A signal processing unit for time of flight measurement includes an oscillation module, a transmission module, a detection module, a multiplier, an analog-to-digital-converter and a processing module. The oscillation module provides m reference phases. The transmission module generates a set of light impulses based on a selection phase selected out of the m reference phases. The detection module receives a set of reflections of the set of light impulses and to generate a detector signal based on the set of reflections. The multiplier obtains a result of a multiplication of the detector signal by a comparison phase. The analog-to-digital-converter converts the result of the multiplier into a digital signal. The processing module determines the comparison phase or the selection phase and calculates an approximate phase difference between the set of generated light impulses and the set of received reflections based on the digital signal.