Multi-Path Dual-Switch DAC for Low-Distortion RF Linearity
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Solution Overview
Problem
Current digital-to-analog converters (DACs), particularly high-speed current steering DACs, face challenges in reducing distortions and power consumption, with existing solutions like quad-path quad-switch architectures experiencing calibration difficulties and linearity degradation, especially in RF applications.
Innovation Solution
The implementation of a multi-path dual-switch DAC architecture with a switch driver having multiple paths and only two switches in a DAC stack, utilizing logic gates to combine output signals and generate drive signals, which reduces power consumption and improves linearity by eliminating the need for dummy DACs and minimizing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed current steering DAC architecture is used to achieve high instantaneous bandwidth, then speed and bandwidth are improved, but distortion increases and dynamic performance deteriorates
Solution Approach 1:
The patent segments the DAC architecture into multiple independent paths (e.g., in-phase and quadrature paths), each with its own switch driver and switches. This segmentation allows each path to be optimized independently for high-speed operation while maintaining overall linearity and low distortion through the combined output of all paths.
2Manufacturing precision
If multiple switches are used in DAC stack to improve linearity, then manufacturing precision is improved, but power consumption increases
Solution Approach 1:
The patent employs a dual-switch configuration in each DAC stack rather than using more switches. This partial action approach achieves the necessary linearity improvement over single-switch designs while avoiding the excessive power consumption that would result from using even more switches in parallel.
3Manufacturing precision
If quad-path quad-switch architecture is used to improve linearity, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple paths (e.g., I and Q paths) that each use a simplified dual-switch configuration, combining their outputs to achieve the linearity benefits of complex architectures while maintaining the simplicity and low power consumption of individual paths. This merging approach avoids the full complexity of a quad-path quad-switch design.
Data Source
AI summary
A multi-path dual-switch DAC refers to implementing multiple paths in a switch driver and only two switches in a DAC stack of a DAC unit. In addition to multiple paths configured to improve the driving ability of the input signals, the switch driver of a multi-path dual-switch DAC unit includes two or more logic gates configured to act as multiplexers combining some of the output signals from different paths. The use of such logic gates enables using only two switches in the DAC stack unit to receive the data. Furthermore, optionally, additional logic gates may be used to combine some other output signals from different paths to generate dummy signals, thus providing internal dummy logic. The multi-path dual-switch DACs described herein may advantageously use half-clock rate and reduce or eliminate supply modulation issues, while also reducing power consumption and improving linearity compared to traditional DAC architectures.