Reconfigurable ADC Resolution Scaling for Wide Dynamic Range Readout
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Solution Overview
Problem
Conventional readout integrated circuits (ROICs) face challenges in efficiently managing wide dynamic range scenes due to limited flexibility in gain adjustment, leading to saturation issues and reduced sensitivity, especially when capturing low-signal levels, which increases power consumption and noise.
Innovation Solution
A reconfigurable ROIC architecture that utilizes per-pixel gain selection based on Received Signal Strength Indicator (RSSI) bits, allowing for on-the-fly adaptations by adjusting the gain of each pixel sensor, thereby maximizing the full-scale photo-diode dynamic range and reducing input-referred noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ROIC uses fixed gain adjustment, then device complexity is reduced, but adaptability to wide dynamic range scenes deteriorates
Solution Approach 1:
The patent implements dynamic gain adjustment by introducing a gain control circuit that receives RSSI signals and automatically adjusts the gain of pixel sensors in real-time. This transforms the static fixed-gain system into a dynamic adaptive system that responds to scene conditions, resolving the contradiction between adaptability and complexity by automating the adjustment process.
Solution Approach 2:
The system employs feedback mechanisms where RSSI (Received Signal Strength Indicator) signals are continuously monitored and fed back to the gain control circuit. This feedback loop enables automatic gain adjustment based on actual signal conditions, allowing the system to adapt to wide dynamic range scenes without manual intervention while managing complexity through automated control.
2Adaptability or versatility
If per-pixel gain adjustment is implemented, then intra-scene dynamic range is improved, but device complexity increases
Solution Approach 1:
The patent segments the image sensor array into multiple regions with different gain settings. Each region can be independently controlled based on its local signal characteristics, allowing per-region or per-pixel gain adjustment. This segmentation approach enables fine-grained dynamic range optimization while managing complexity by organizing control into manageable regional units.
Solution Approach 2:
The system applies local quality control by allowing different gain values to be applied to different spatial regions or individual pixels based on their specific signal conditions. This enables each pixel or region to operate at optimal gain settings for its local scene characteristics, maximizing intra-scene dynamic range while using RSSI-based automation to manage the complexity of multiple gain settings.
3Measurement precision
If high gain is used for low-signal levels, then sensitivity is improved, but saturation issues occur in high-signal regions
Solution Approach 1:
The patent dynamically changes the gain parameter based on signal strength conditions. By monitoring RSSI levels and adjusting gain accordingly, the system applies high gain only when signal levels are low (improving sensitivity) while automatically reducing gain when signal levels are high (preventing saturation). This parameter adaptation resolves the contradiction by making gain a variable rather than a fixed value.
Solution Approach 2:
The system transitions from static gain settings to dynamic gain adjustment that responds to real-time signal conditions. The gain control circuit continuously adapts gain levels based on RSSI feedback, enabling the system to maintain optimal sensitivity for low signals while automatically preventing saturation in high-signal regions through real-time dynamic control.
4Use of energy by moving object
If automatic gain adjustment is implemented, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The patent implements self-service automation where the gain control circuit autonomously adjusts pixel sensor gains based on RSSI signals without requiring external control. The system monitors its own operating conditions and automatically optimizes gain settings, reducing the need for manual intervention and external control circuitry. This self-service approach reduces overall system complexity while enabling power-efficient automatic gain adjustment.
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 enhances intra-scene dynamic range, reduces power consumption, and improves signal-to-noise ratio (SNR) by allowing per-pixel gain adjustments, preventing saturation and increasing sensitivity across a wide range of signal levels.
Implementation Method 1
The image sensors convert incident electromagnetic radiation to electrical signals that may be represented as digital images
Data Source
AI summary
An integrated circuit (IC) includes an analog to digital converter (ADC) circuit having an ADC input and an ADC output. The ADC circuit is configured to receive an input signal at the ADC input and generate a digital output signal at the ADC output based on the input signal. An ADC circuit path is coupled between the ADC input and the ADC output. The ADC circuit comprises a plurality of capacitors coupled between reference voltage sources and the ADC circuit path. The ADC has a reconfigurable resolution and a reconfigurable sampling rate. The ADC circuit is configured to scale the reference voltage sources and/or the plurality of capacitors based on the reconfigurable resolution.