Differential DAC Topology for Higher Resolution With Lower Area
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Solution Overview
Problem
Existing digital-to-analog converters (DACs) face challenges in increasing bit resolution while minimizing area and current consumption, as additional circuit elements are often included for purposes other than improving linearity and noise, leading to increased design costs.
Innovation Solution
The proposed DAC architecture includes a first and second DAC sub-circuit with specific transistor and switch configurations, utilizing a single-ended current pump arm to enhance resolution, thereby reducing the number of required components and minimizing area and current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of circuit elements in a DAC system is increased to improve resolution, then the resolution of converted outputs is improved, but the area and current consumption increase
Solution Approach 1:
The DAC system is divided into multiple subsystems, each handling specific bit ranges. This segmentation allows independent optimization of each subsystem's circuit elements, reducing the total number of components needed while maintaining overall resolution. The differential architecture further segments the signal path into separate positive and negative channels, improving efficiency.
Solution Approach 2:
Circuit elements such as transistors and switches are designed to serve multiple functions simultaneously. For example, the same transistor network is used for both differential signal generation and noise reduction, eliminating the need for separate dedicated circuits for each function and thereby reducing total component count and area.
2Measurement precision
If the number of circuit elements in a DAC system is increased to improve resolution, then the resolution of converted outputs is improved, but the current consumption increases
Solution Approach 1:
The current consumption is segmented and distributed across multiple subsystems rather than concentrated in a single high-resolution converter. Each subsystem operates at lower current levels, and their combined output achieves the target resolution, thereby reducing total power consumption compared to a monolithic approach.
Solution Approach 2:
The same circuit elements are used for multiple purposes including resolution enhancement, linearity improvement, and noise reduction. This multi-functionality eliminates redundant circuits that would otherwise consume additional current, achieving high resolution without proportional increases in power consumption.
3Reliability
If transistors and switches are added for improving linearity and reducing noise, then linearity and noise performance are improved, but the design area increases
Solution Approach 1:
The differential DAC architecture uses the same transistor and switch networks to simultaneously achieve high resolution, improve linearity, and reduce noise. By designing circuits that perform multiple functions concurrently, the patent avoids adding separate dedicated circuits for each performance metric, thereby maintaining compact area while achieving superior overall performance.
Data Source
AI summary
Embodiments disclosed herein relate to digital-to-analog converters (DACs), and more particularly, to architecture thereof for improving bit resolution of the DACs. In an embodiment, a circuit is provided that includes a first DAC sub-circuit, a second DAC sub-circuit, and a control circuit coupled to control the first and second DAC sub-circuits. The first DAC sub-circuit includes a first set of transistors and a first set of switches coupled to the first set of transistors and to output nodes. The second DAC sub-circuit includes a second set of transistors coupled to the first set of transistors and a second set of switches coupled to the second set of transistors and to the output nodes.