Pixel Circuit Pre-Charge Scheme for Wider Dynamic Range
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Solution Overview
Problem
Solid-state imaging devices face challenges in achieving high dynamic range while maintaining low power consumption, especially in battery-powered applications such as electric vehicles.
Innovation Solution
The implementation of a pixel circuit with a photoelectric conversion circuit, an integration capacitor, and a supplementary circuit that pre-charges a working node to a potential different from the supply potential, allowing for increased voltage swing and dynamic range without significant power consumption increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration capacitor is pre-charged to a potential different from the supply potential, then the dynamic range is increased, but the device complexity increases
Solution Approach 1:
The supplementary circuit pre-charges the working node to a predetermined potential different from the supply potential before the integration period begins. This preliminary action creates a larger voltage swing range for the integration capacitor, enabling the pixel circuit to accommodate both very low and very high light intensities within the same hardware architecture, thus increasing dynamic range without requiring multiple capacitors or complex switching mechanisms.
2Measurement precision
If the photoelectric conversion circuit operates over a wide dynamic range, then the measurement precision improves, but the power consumption increases
Solution Approach 1:
The patent changes the voltage parameter at the working node by introducing a supplementary circuit that sets the initial potential to a value different from the supply potential. This parameter change enables the integration capacitor to utilize the full voltage swing range from the supply potential to the pre-charged potential, maximizing the dynamic range. The circuit maintains low power consumption by using simple capacitive coupling and voltage switching rather than active current amplification throughout the integration period.
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 configuration enhances the dynamic range of the pixel circuit while keeping power consumption low, effectively addressing the need for efficient imaging in battery-powered systems.
Implementation Method 1
The integration capacitor is configured to integrate the photocurrent on the storage electrode in an integration period
Implementation Method 2
photoelectric conversion elements generating a photocurrent in proportion to the received radiation intensity
Data Source
AI summary
A pixel circuit (100) includes a photoelectric conversion circuit (110), an integration capacitor (Cint) and a supplementary circuit (120). The photoelectric conversion circuit (110) generates and outputs a photocurrent (Iphoto). The integration capacitor (Cint) includes a storage electrode (CintS) and a reference electrode (CintR), wherein the reference electrode (CintR) is connected to a first supply potential (VSUP1), and wherein the integration capacitor (Cint) is configured to integrate the photocurrent on the storage electrode (CintS) in an integration period (Tint). The supplementary circuit (120) pre-charges a working node (WN) between the photoelectric conversion circuit (110) and the storage electrode (CintS) to a pre-charge potential (Vpre) that differs from the first supply potential (VSUP1).