Pixel Readout Circuit with Shared Derivation for 10 KHz Imaging
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Solution Overview
Problem
Conventional video imaging readout circuits are limited in achieving high frame rates due to practical limitations of analog circuits and require complex digital processing, which severely limits pixel density and increases costs.
Innovation Solution
A readout circuit with pixel integration circuits operating at hundreds of Hertz for analog signal integration and pixel derivation circuits operating at 10 KHz for digital signal derivation, allowing for high frame rate video capture with compact digital derivation circuitry and high pixel density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional analog readout circuits are used, then the circuit complexity is low, but the achievable frame rate is limited to hundreds of Hertz
Solution Approach 1:
The readout circuit is segmented into multiple independent pixel readout circuits, each capable of autonomous operation. Each pixel readout circuit includes its own integration circuit and derivation circuit, allowing parallel processing of multiple pixels simultaneously. This segmentation enables the system to achieve high frame rates by distributing the processing load across numerous independent units rather than using a single complex centralized circuit.
2Speed
If digital in-pixel processing is implemented to achieve high frame rates, then the frame rate can be increased, but the pixel density is severely limited due to larger circuit area
Solution Approach 1:
The complex digital processing functions are extracted from individual pixels and relocated to shared derivation circuits that serve multiple pixels. Each pixel retains only the essential integration circuit and minimal derivation logic, while more sophisticated processing is performed by shared resources. This extraction dramatically reduces the area required per pixel while maintaining high frame rate capability through the shared derivation circuits.
Solution Approach 2:
The derivation circuits are designed to serve multiple pixels simultaneously, making them multi-functional resources. A single derivation circuit can process signals from several pixels, performing derivative calculations and event detection for each. This universality reduces the total number of derivation circuits needed, thereby reducing overall circuit area and enabling higher pixel density while maintaining high frame rate operation.
3Speed
If complex digital processing modules are incorporated within each pixel, then high frame rate detection is enabled, but the fabrication cost increases
Solution Approach 1:
Multiple pixel readout circuits are merged to share common derivation circuits and other processing resources. Instead of each pixel having its own complete processing chain, the system combines several pixels' integration outputs and feeds them into shared derivation circuits. This merging reduces the total component count, simplifies the fabrication process, and lowers costs while maintaining the ability to detect fast events at high frame rates across all pixels.
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
Enables high frame rate video capture (up to 10 KHz) with high pixel density (100 μm² or less) and moderate fabrication costs, overcoming the limitations of conventional techniques.
Implementation Method 1
The capacitive unit is controllably linked to input channel for accumulating charge corresponding to received intensity generated by said pixel during a single frame period
Implementation Method 2
an input channel for receiving an image signal corresponding to electrical output of a photosensitive element of the pixel
Data Source
AI summary
A pixel readout circuit and a technique for imaging are disclosed. The circuit includes: an array of pixel integration circuits, each adapted for receiving an electric signal indicative of photocurrent of light sensitive pixel of a pixel matrix, integrate the electric signal over a frame period, and output the integrated signal at an imaging frame rate being one over the period; and an array of pixel derivation circuits, each includes a signal preprocessing channel for receiving a total electric signal indicative of at least a component of the photocurrent(s) of a cluster of respective light sensitive pixel(s); and a comparison unit adapted to analyze the total electric signal to determine digital data indicative of a change in the total electric signal relative to one or more thresholds; and a digital output utility adapted to readout of the digital data at a second rate different than the frame rate.