Time-of-Flight Sensor Pixel Binning Analog Signal Combination
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Solution Overview
Problem
Current time-of-flight sensors using pixel binning face limitations due to increased noise in the readout stage and complexity in implementing correlated double sampling (CDS) and differential readout stages, which also consume significant power.
Innovation Solution
A method and switched device for time-of-flight sensors that enable column-wise combination of readout signals in the analog domain, reducing the number of analog-to-digital conversions and noise, and allowing for simpler signal processing with CDS and differential signals by combining readout signals from multiple pixels before digitization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixel binning is applied to improve signal-to-noise ratio, then more photons can be collected on the combined pixel area, but increased noise appears in the readout stage
Solution Approach 1:
The patent applies preliminary action by performing analog signal combination of multiple pixel readout signals before they enter the digital domain. By combining signals in the analog domain first, the system reduces the number of subsequent digital operations needed, thereby minimizing the introduction of readout noise while maintaining the signal-to-noise ratio benefits of pixel binning.
2Measurement precision
If correlated double sampling and differential readout stages are implemented to improve signal processing, then measurement precision is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the correlated double sampling and differential readout operations into a unified analog domain processing stage. By combining multiple pixel signals in the analog domain before digitization, the system achieves the precision benefits of CDS and differential readout while reducing the overall device complexity and the number of separate processing stages required.
3Productivity
If more analog-to-digital converters are used to handle increased signal processing requirements, then productivity is improved, but power consumption increases
Solution Approach 1:
The patent merges multiple pixel readout signals into combined analog signals before digitization, reducing the total number of analog-to-digital conversions required. This approach maintains processing throughput by preserving signal integrity while significantly reducing the number of ADCs needed, thereby lowering power consumption.
4Measurement precision
If more analog-to-digital converters are implemented for digitizing readout signals, then measurement precision is maintained, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing signal combination in the analog domain before digitization. This preliminary combining reduces the number of individual signals that need to be converted to digital, thereby reducing the number of ADCs required while maintaining measurement precision through preserved signal integrity in the analog domain.
Data Source
AI summary
An implementation of a method for pixel binning in a time-of-flight sensor, includes receiving a first readout signal from a first column of a pixel array of the time-of-flight sensor and receiving a second readout signal from a second column of the pixel array. The method further includes combining the first readout signal and the second readout signal to obtain a common analog signal useable to determine a distance based on at least two pixels of the time-of-flight sensor.