Resistor-String DAC Switching Layout for Smaller Chip Area
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Solution Overview
Problem
Resistor string type D/A converters require a large number of switches, leading to increased chip size due to the need for two switches between each pair of resistors, which complicates the design and increases physical dimensions.
Innovation Solution
A resistor string type D/A converter design that eliminates the need for multiple switches between each pair of higher-order analog voltages by using a higher-order resistor string with controlled switches and decoders to generate and output higher-order analog voltages, reducing the overall number of switches required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two switches are connected to each voltage drawing point of the higher-order resistor string, then the D/A converter can achieve high resolution and accurate voltage selection, but the number of switches increases significantly, causing the chip size to become larger
Solution Approach 1:
The patent divides the switch control into two independent segments: higher-order switches controlled by higher-order bits and lower-order switches controlled by lower-order bits. This segmentation allows each switch to be controlled independently based on the corresponding bit significance, reducing the complexity of controlling two switches per voltage drawing point while maintaining the ability to select precise voltage levels through the combined action of both switch sets.
2Measurement precision
If two switches are provided between each pair of resistors for high-resolution D/A conversion, then voltage selection accuracy is improved, but the device complexity and number of components increase
Solution Approach 1:
The control system is segmented into higher-order and lower-order control paths. The higher-order switches handle the most significant bits of the digital input, while the lower-order switches handle the least significant bits. This segmentation reduces device complexity by organizing the switch control logic into hierarchical levels, making the system more manageable and reducing the interconnections required compared to a unified two-switch-per-point approach.
Solution Approach 2:
The patent implements dynamic control of switches based on the digital input signal bits. The higher-order switches are dynamically controlled by higher-order bits, and the lower-order switches are dynamically controlled by lower-order bits. This dynamic control mechanism allows the system to adaptively select the appropriate voltage level by activating specific switch combinations, thereby achieving high precision D/A conversion with reduced overall complexity through intelligent control rather than static redundant switching structures.
Data Source
AI summary
A resistor string type D/A converter includes a higher-order decoder to which a digital signal is input, a higher-order resistor string in which a plurality of resistors and a plurality of voltage drawing points are alternately connected between a first reference voltage and a second reference voltage, the higher-order resistor string being configured to output a plurality of first voltages, each from a respective one of the plurality of voltage drawing points, a plurality of first higher-order switches connected to the plurality of voltage drawing points in a one-to-one configuration, conductive states of the first higher-order switches being controlled based on the digital signal, and a conversion unit that outputs a second voltage based on the plurality of the first voltages supplied through the plurality of first higher-order switches. The higher-order decoder brings two first higher-order switches into conduction based on the digital signal.