Diode Array Current Mirror Layout for Low-Wiring Pixel Referencing
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Solution Overview
Problem
In large diode arrays, such as LED arrays or image sensors, accurately referencing individual image elements with a low number of wiring lines is challenging due to error sources affecting voltage referencing and the complexity of current referencing methods.
Innovation Solution
A diode array design featuring a distribution transistor and input transistors for each image element, forming a current mirror to supply reference current via a single feed line, reducing the number of wiring lines and maintaining low mismatch errors by sharing temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current referencing is performed with one output line per image element, then measurement precision is improved, but device complexity increases due to massive number of wiring lines
Solution Approach 1:
The array is divided into multiple diode arrays, each containing a subset of image elements. Each diode array has its own distribution transistor and shares a common feed line, segmenting the referencing function to reduce the number of wiring lines from one-per-pixel to one-per-diode-array.
Solution Approach 2:
Multiple image elements within each diode array share a common feed line and reference current source. The distribution transistor distributes the reference current to multiple image elements simultaneously, merging the referencing function to reduce wiring complexity.
2Device complexity
If voltage referencing is used to keep wiring lines low, then device complexity is reduced, but measurement precision deteriorates due to error sources
Solution Approach 1:
A distribution transistor is introduced as an intermediary component between the feed line and multiple image elements. This transistor enables precise current distribution to multiple pixels while maintaining a reduced wiring structure, acting as a mediator between voltage referencing simplicity and current referencing precision.
3Area of stationary object
If the number of diode arrays is increased to cover large arrays, then area coverage is improved, but device complexity increases due to more distribution transistors
Solution Approach 1:
Each distribution transistor is designed to serve multiple image elements within its diode array, making it a universal component that handles referencing for multiple pixels simultaneously. This multi-functionality reduces the total number of distribution transistors needed compared to a one-to-one mapping approach.
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 precise and accurate referencing of image elements with a significant reduction in wiring complexity, suitable for large arrays, by using a distribution current mirror and output current mirrors to inherit and distribute reference current efficiently.
Implementation Method 1
The distribution transistor forms a distribution current mirror with the respective input transistor of at least two image elements
Data Source
AI summary
A diode array with at least two image elements. The diode array includes a distribution transistor as well as a feed line for receiving a reference current and a first supply terminal coupled to the distribution transistor for supplying the distribution transistor. A diode and an input transistor are provided for each image element, each of which is coupled to the diode for supplying the diode. The distribution transistor forms a distribution current mirror with the respective input transistor of at least two image elements.