Reconfigurable Column Amplifier for Dynamic Range and Read Noise
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Solution Overview
Problem
Existing image sensor systems face challenges in achieving high dynamic range and ultra-low noise, with differential and single-ended column amplifiers having different operational benefits depending on the application.
Innovation Solution
A dual-mode column amplifier that can be configured between differential and single-ended modes of operation, utilizing a transistor bank and mode select circuitry to switch between these modes based on control inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a differential column amplifier is used, then high dynamic range is achieved, but read noise increases
Solution Approach 1:
The column amplifier is designed with dynamic reconfigurability, allowing it to switch between differential and single-ended modes of operation. This is achieved through mode select circuitry that can dynamically alter the transistor connections based on the imaging requirements, enabling the system to adapt its noise characteristics and dynamic range performance in real-time
Solution Approach 2:
The invention changes the operational parameters of the column amplifier by switching between two distinct modes: differential mode for high dynamic range applications and single-ended mode for ultra-low noise applications. This parameter change is controlled through mode select circuitry that reconfigures the transistor bank connections, allowing optimization of the noise-dynamic range tradeoff based on specific imaging conditions
2Object-generated harmful factors
If a single-ended column amplifier is used, then read noise is reduced, but dynamic range is limited
Solution Approach 1:
The column amplifier incorporates dynamic reconfigurability through mode select circuitry that can switch the amplifier topology between single-ended and differential modes. This allows the system to dynamically select the single-ended configuration when ultra-low noise performance is the priority, while maintaining the capability to switch to differential mode when high dynamic range is required
Solution Approach 2:
The column amplifier is designed as a universal circuit that can perform multiple functions by operating in two distinct modes. The same physical hardware (transistor bank and associated circuitry) can be configured to provide either single-ended operation for low-noise applications or differential operation for high dynamic range applications, eliminating the need for separate dedicated circuits
3Adaptability or versatility
If mode select circuitry is added to enable dual-mode operation, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The mode select circuitry is integrated with the existing transistor bank and amplifier circuitry, merging the switching function with the amplification function. The mode select switches are strategically placed within the transistor connections, allowing a single control signal to reconfigure the entire amplifier topology without requiring separate dedicated switching circuits for each transistor
Data Source
AI summary
Examples include an image sensor comprising a pixel array having at least one column of addressable pixel sensors, and a column amplifier coupled to the at least one column of addressable pixel sensors, the column amplifier comprising a transistor bank including a plurality of transistors, and mode select circuitry coupled to the transistor bank and configured to establish one or more connections among the plurality of transistors to configure the column amplifier to operate in one of a differential mode of operation and a single-ended mode of operation.