Higher-Order Resistor-String DAC With Fewer Switches
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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 per higher-order analog voltage by using a higher-order resistor string with controlled switches and decoders to manage voltage divisions, reducing the overall number of switches and thus the chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two switches are provided between each pair of resistors in the higher-order resistor string, then the D/A converter can achieve high resolution and accurate voltage selection, but the chip size becomes larger due to the increased number of switches
Solution Approach 1:
The patent segments the control function by dividing the digital input into higher-order bits (controlling first switches) and lower-order bits (controlling second switches). This segmentation allows the higher-order switches to select coarse voltage ranges while lower-order switches provide fine adjustments, reducing the need for every switch to handle the full resolution requirement.
Solution Approach 2:
The patent introduces a hierarchical control structure with two dimensions of switch control: higher-order switches controlled by higher-order bits and lower-order switches controlled by lower-order bits. This dimensional approach to control allows the system to achieve full resolution functionality while using fewer total switches than a conventional single-level architecture would require.
2Measurement precision
If a higher-order and lower-order division scheme is implemented, then the D/A converter can achieve high resolution with reduced size, but the device complexity increases due to multiple decoders and switch networks
Solution Approach 1:
The patent segments both the digital input (into higher-order and lower-order bits) and the switch control (into first switches and second switches). This segmentation of control functions allows each decoder to handle a portion of the resolution requirement, simplifying individual decoder logic while maintaining overall high resolution through their combined operation.
Solution Approach 2:
The patent implements dynamic control where the higher-order decoder and lower-order decoder operate hierarchically. The higher-order decoder establishes the coarse voltage range by controlling first switches, and the lower-order decoder refines the selection by controlling second switches. This dynamic, multi-level control approach achieves high resolution while keeping each decoder's complexity manageable.
Data Source
AI summary
A resistor string digital-to-analog converter includes an input terminal receiving a digital input signal in digital code, an output terminal revealing an analog output signal in analog voltage, a first plurality of voltage-acquisition nodes including a first pair of nodes which is adjacent to each other, a first plurality of resistors being connected in series via the first plurality of voltage-acquisition nodes, a second pair of nodes revealing a pair of analog voltages, a high-order voltage-acquisition circuit providing conduction between a respective one of the first pair of nodes and a respective one of the second pair of nodes in accordance with the digital input signal, a low-order converter generating the analog output signal, which is obtained by interpolating one and the other of the pair of analog voltages in accordance with the digital input signal.