Resistor-String D/A Converter With Variable Resistors for High-Bit Precision
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Solution Overview
Problem
Conventional resistor-string D/A converters are impractical for high bit output applications due to the increased number of wires, resistors, and switches required, leading to large circuit size and potential decreases in precision and increased current consumption.
Innovation Solution
A D/A converter design utilizing (2^n)−1 resistors of equal resistance connected in series, with two variable resistors whose resistances are determined by the digital signal, reducing the number of wires and switches needed and eliminating the need for internal D/A converters, thus minimizing circuit size and maintaining high precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional resistor-string D/A converter is used for high bit output applications, then the conversion precision can be maintained, but the number of wires, resistors, and switches increases significantly, leading to large circuit size
Solution Approach 1:
The patent divides the digital signal into upper bits and lower bits, using a resistor-string circuit for upper bits and variable resistors for lower bits. This segmentation allows the circuit to handle high-bit conversion without requiring a complete resistor-string for all bits, thus reducing circuit size while maintaining precision.
Solution Approach 2:
The patent transitions from a one-dimensional resistor-string approach to a two-dimensional structure by combining resistor-string circuits with variable resistors. This dimensional change allows the circuit to achieve high-bit conversion capability without linearly increasing the number of components.
2Productivity
If a conventional resistor-string D/A converter is used for high bit output applications, then the conversion can be performed, but the number of switches increases, leading to increased current consumption
Solution Approach 1:
The patent segments the conversion function between resistor-string circuits (for upper bits) and variable resistors (for lower bits). This segmentation reduces the number of switches needed compared to a full resistor-string approach, thereby reducing current consumption while maintaining conversion capability.
3Manufacturing precision
If the number of resistors is increased for high bit output, then the conversion resolution is improved, but the circuit size and manufacturing complexity increase
Solution Approach 1:
The patent segments the resolution requirement between the resistor-string circuit (providing coarse resolution for upper bits) and variable resistors (providing fine resolution for lower bits). This segmentation allows high conversion resolution without manufacturing all the resistors needed for a complete high-bit resistor-string.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the conversion of high bit digital signals (9 to 11 bits) with reduced circuit size and current consumption, while maintaining high precision by relying on the relative precision of the variable resistors connected to reference voltages.
Implementation Method 1
voltage dividing means containing (2^n)−1 resistors of an equal resistance connected in series, a first reference voltage and a second reference voltage being applied across both terminals of the resistors
Implementation Method 2
two variable resistors connected to the terminals of the (2^n)−1 resistors connected in series, the variable resistors exhibiting resistances determined according to the m lower bits of the digital signal
Data Source
AI summary
A variable resistor is connected to each terminal of (2^n)−1 resistors R connected in series. The variable resistors have resistances RH and RL determined according to a digital signal containing m lower bits LoB<m−1:0>.