Capacitor-Array D/A Conversion Circuit for Accuracy in Smaller Layouts
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Solution Overview
Problem
Existing D/A conversion circuits, particularly in semiconductor ICs, face challenges in maintaining high conversion accuracy due to device variation during manufacturing, which affects the capacitance ratio accuracy and increases the circuit size.
Innovation Solution
A D/A conversion circuit design that includes a first and second D/A converting section with capacitor arrays and switch arrays, where the control circuit dynamically allocates capacitors based on input digital data bits, enhancing capacitance ratio accuracy and reducing layout area through efficient layout arrangement and the use of different capacitor types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the layout area of the capacitor is enlarged to enhance the capacitance ratio accuracy, then the conversion accuracy is improved, but the circuit size increases
Solution Approach 1:
The capacitor array is divided into multiple groups, with each group corresponding to different bit weights. The switch array selectively connects these groups to different nodes based on the input digital data, enabling dynamic allocation of capacitance values without requiring a single large capacitor structure
Solution Approach 2:
The circuit employs dynamic switch control to reallocate capacitor groups during operation. The switch array dynamically connects or disconnects specific capacitor groups from the output node based on the binary weighted values represented by input digital data, allowing the effective capacitance ratio to be programmably adjusted rather than fixed by physical layout
2Manufacturing precision
If device variation is reduced to maintain conversion accuracy, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The circuit changes the operational parameters by dynamically reconfiguring which capacitor groups are activated based on input digital data. This parameter change approach allows the system to adapt to device variations by programmatically adjusting the effective capacitance ratios rather than relying on precise fixed physical dimensions
Solution Approach 2:
Multiple capacitor groups are created as copies with identical physical structures, but they are assigned different binary weighted values through switch control. This copying approach allows the system to achieve precise capacitance ratios through control logic rather than requiring each capacitor to be physically unique in size
Data Source
AI summary
A D/A conversion circuit includes a first D/A converting section which is connected with an output node, a first serial capacitor which is disposed between the output node and a first node, a second D/A converting section which is connected with the first node, and a control circuit. The first D/A converting section includes a first capacitor array section and a first switch array section. The second D/A converting section includes a second capacitor array section and a second switch array section. The control circuit performs a switch control for dynamically changing allocation of the capacitors to the respective bits of input digital data for the first switch array section of the first D/A converting section.