Weighted-Resistor DAC Circuit Using T-Network Speed Equalization
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Solution Overview
Problem
Digital-to-analog converter (DAC) circuitry with weighted resistance elements experiences speed differences between variously weighted elements, leading to glitches and increased noise due to disparate response speeds, which are not effectively addressed by existing R-2R ladder architectures or series resistor strings.
Innovation Solution
Incorporating T-networks into the weighted resistance elements to equalize response speeds among differently weighted elements, allowing for simultaneous reduction of power consumption, area, noise, and distortion, while maintaining effective element weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If weighted resistance elements with different weights are used in DAC circuitry, then the ability to convert digital signals to analog signals with proper weighting is improved, but response speed differences between elements increase causing glitches and noise
Solution Approach 1:
The patent changes the resistance parameters by introducing T-networks with specific resistance values (R1, R2, R3) that transform the effective resistance of weighted elements. This parameter transformation allows different weighted elements to operate at similar speeds while maintaining their weighting functions, resolving the contradiction between conversion accuracy and response speed consistency
Solution Approach 2:
The T-network acts as an intermediary circuit between the switch and the weighted resistance element. It mediates the response speed by introducing additional resistance paths that slow down faster elements and maintain overall weighting accuracy, thus bridging the speed difference between differently weighted elements
2Ease of manufacture
If R-2R ladder architectures or series resistor strings are used, then weighted resistance elements can be implemented, but they fail to equalize response speeds leading to transient glitches and increased noise
Solution Approach 1:
The patent segments the weighted resistance element into a T-network configuration with separate resistance components (R1, R2, R3) rather than using a single series resistor. This segmentation allows independent optimization of each resistance value to control response speed while maintaining the overall weighting function, thereby reducing transient glitches and noise
Solution Approach 2:
The T-network introduces local quality differences by assigning different resistance values to different parts of the circuit (R1 for series, R2 and R3 for parallel paths). This local differentiation allows precise control over the response speed of each weighted element, eliminating the uniform response speed limitation of R-2R ladders and series resistor strings
Data Source
AI summary
Digital-to-analog converter circuitry is described. The digital-to-analog converter circuitry includes a plurality of weighted resistance elements. A first weighted resistance element includes a switch coupled to a reference voltage. The first weighted resistance element also includes a T-network coupled to the switch. The T-network approximately equalizes a first response speed of the first weighted resistance element with a response speed of a differently weighted resistance element.