Digital-to-analog converter with stacked current dividers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital-to-analog converters realized as thermometer-coded converters achieve high accuracy and speed but result in high costs due to the large area of silicon required for fabrication.
Innovation Solution
A digital-to-analog converter design utilizing a stack of two current dividers with reduced circuit parts, including a first and second current divider with switching arrangements, allowing selective coupling of current sources to converter and dummy outputs based on control signals, thereby minimizing the number of current sources and achieving high accuracy at lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermometer-coded converter is used, then high accuracy and high speed are achieved, but high cost results due to large silicon area required
Solution Approach 1:
The converter is divided into multiple stages: a first current divider with K output terminals and a second current divider with P output terminals. This segmentation allows the system to achieve high-resolution conversion without requiring all current sources to be simultaneously active, thereby reducing the silicon area while maintaining accuracy.
Solution Approach 2:
The patent transitions from a single-plane current source arrangement to a multi-stage hierarchical structure with series-connected current dividers. This dimensional reorganization allows efficient current distribution across multiple levels, reducing the lateral silicon footprint while preserving the thermometer-coded conversion accuracy.
2Manufacturing precision
If a thermometer-coded converter with parallel branches is fabricated, then high accuracy is achieved, but high cost results due to area of silicon required
Solution Approach 1:
By segmenting the converter into series-connected current dividers with fewer simultaneous current sources, the patent reduces the total component count and interconnections required. This segmentation lowers fabrication complexity and cost while maintaining the precision needed for accurate digital-to-analog conversion.
Solution Approach 2:
The patent uses current mirroring techniques where a smaller set of current sources in the first current divider generates scaled current copies that are distributed through the second current divider. This copying approach reduces the number of physical current sources needed, thereby reducing fabrication area and cost while preserving conversion accuracy.
3Ease of manufacture
If the number of current sources is reduced, then cost savings are achieved, but maintaining high accuracy becomes difficult
Solution Approach 1:
The patent arranges current dividers in a series hierarchy across multiple dimensions rather than using a single-plane parallel structure. This multi-dimensional arrangement allows a reduced number of current sources to effectively serve multiple output terminals through staged current distribution, maintaining accuracy with fewer components.
Solution Approach 2:
The first current divider acts as an intermediary that receives current from a reduced set of current sources and distributes it to multiple output terminals. This intermediary structure enables accurate current allocation to all necessary outputs without requiring a proportional increase in current source数量, thus maintaining precision while reducing component count and cost.
Data Source
AI summary
A digital-to-analog converter comprises a converter output (11), a dummy output (12), a first number N of current sources (13-17), a first switching arrangement (18), a first current divider (24), a second switching arrangement (31) and a second current divider (60). The current sources (13-17) are coupled via the first switching arrangement (18) to the converter output (11), the dummy output (12) or to an input current terminal (25) of the first current divider (24). The output current terminals (26-30) of the first current divider (24) are coupled via the second switching arrangement (31) to the converter output (11), the dummy output (12) or to an input current terminal (61) of the second current divider (60). The output current terminals (63-66) of the second current divider (60) are coupled to the converter output (11) or the dummy output (12).