Resistive DAC Summing Junction Routing for Low-Distortion Output
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Solution Overview
Problem
Digital-to-analog converters (DACs) face challenges in achieving high dynamic range and minimizing distortion due to parasitic impedances in combined force and sense paths, which can result in errors such as clipping and omission of signal components outside the system's range.
Innovation Solution
The implementation of separate force and sense paths in DACs, along with a voltage reference generator that compensates for impedance variations, reduces distortion by isolating parasitic impedances in the sense path and synchronizing on-chip and off-chip impedances, thereby maintaining signal integrity across a wide range of power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If combined force and sense paths are used in DAC, then device complexity is reduced, but distortion increases due to parasitic impedances
Solution Approach 1:
The patent divides the combined force and sense path into separate force path and sense path segments. The force path carries the output current from the DAC to the amplifier, while the sense path separately carries the sense voltage from the amplifier input back to the DAC. This segmentation isolates parasitic impedances in each path, preventing their interaction and reducing distortion while maintaining manageable device complexity through structured routing.
2Object-affected harmful factors
If separate force and sense paths are implemented, then distortion is reduced, but device complexity increases
Solution Approach 1:
The patent resolves routing complexity by transitioning to a star configuration and tree configuration layout. In this dimensional arrangement, multiple force paths and sense paths converge at centralized summing junctions and distribution points rather than requiring complex point-to-point routing. This spatial reorganization reduces the number of interconnections and simplifies the overall routing architecture while preserving the distortion-reducing benefits of separate paths.
3Measurement precision
If parasitic impedances are present in sense path, then measurement precision degrades, but device complexity remains unchanged
Solution Approach 1:
The patent extracts the sense voltage measurement function from the force path by creating a dedicated sense path that separately routes the sense voltage from the amplifier input back to the DAC. This extraction isolates the measurement function from the power delivery function, allowing the sense path to be optimized for low-impedance voltage sensing while the force path handles current delivery. The separate sense path minimizes the impact of parasitic impedances on measurement precision without requiring changes to the overall device architecture.
Data Source
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AI summary
Described herein are DACs with low distortion for high dynamic range (HDR), extremely high dynamic range (EHDR), and other suitable applications. Some embodiments relate to a device including a DAC configured for coupling to an amplifier via a force path and a sense path. For example, the DAC may provide output current to the amplifier via the force path, and the DAC may sense the input voltage of the amplifier via the sense path. Accordingly, distortion such as harmonic distortion and/or gain offset from parasitic impedances in the force and/or sense paths may be reduced or eliminated. Some embodiments relate to a DAC including a voltage reference generator configured to compensate for variations in impedances of the DAC, such as due to semiconductor process variation. Accordingly, distortion in the DAC output due to variations in the DAC impedances may be reduced or eliminated.