Master-Slave Photodiode Bias Amplifier for Pixel Area Reduction
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Solution Overview
Problem
As image sensors become smaller and pixel pitches decrease, traditional pixel amplifiers occupy increasing space and consume more power, necessitating a reduction in area and power allocation for pixel amplifiers.
Innovation Solution
A pixel master-slave photodiode bias control amplifier system is introduced, where a master pixel with a Sackinger current mirror and shared amplification components connects to multiple slave pixels, reducing the number of transistors and space while maintaining a constant bias voltage, thereby minimizing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pixel amplifiers are used, then reliable photodiode bias control is achieved, but pixel area and power consumption increase significantly
Solution Approach 1:
Multiple slave pixels share a single master pixel's amplification member (Sackinger current mirror), merging previously separate amplifier functions into a shared resource. This reduces the total transistor count from 5 per pixel to a shared structure serving multiple pixels, directly reducing pixel area while maintaining bias control reliability
Solution Approach 2:
The master pixel's amplification member serves multiple functions: it provides bias control for the master detector and simultaneously serves as the amplification element for multiple slave pixels. This multi-functional design eliminates redundant amplifier circuits, reducing overall pixel area consumption
2Power
If traditional five-transistor differential amplifiers are used, then sufficient amplification is provided, but current consumption exceeds 1 nA per pixel
Solution Approach 1:
Multiple slave pixels share the master pixel's amplification member and integrator resources, merging previously separate power-consuming amplifier circuits. This shared architecture reduces total current consumption across multiple pixels while maintaining sufficient amplification capability for each individual pixel
Solution Approach 2:
The patent employs a Sackinger current mirror with specific transistor sizing and biasing parameters optimized for low power operation. By carefully selecting transistor dimensions and bias conditions, the amplification member achieves required gain while consuming less than 1 nA per pixel, representing an optimization of electrical parameters for energy efficiency
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 system effectively decreases the space and power required for pixel amplifiers, achieving less than 1 nA current consumption compared to traditional five-transistor differential amplifiers, while maintaining responsive illumination energy conversion across multiple pixels.
Implementation Method 1
a detector configured to receive an input illumination energy and direct a detector current to an amplification member in response to the input illumination energy
Implementation Method 2
a slave detector configured to receive the input illumination energy and direct a slave detector current to a slave control transistor in response to the input illumination energy
Data Source
AI summary
A pixel master-slave photodiode bias control amplifier system is disclosed. The pixel master-slave photodiode bias control amplifier system may include a master pixel and one or more slave pixels. The slave pixel(s) may be connected to a portion of the master pixel. In this manner, components may be shared between/among the master pixel and the slave pixel(s); thus, for example, optimizing the component count of the pixel master-slave photodiode bias control amplifier system and the size occupied by the pixel master-slave photodiode bias control amplifier system.