SAR ADC Full-Scale Voltage Auto-Tuning with Capacitor Array Control
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Solution Overview
Problem
Existing SAR ADCs require manual tuning of the full-scale voltage (VFS), which is sensitive to component variations and reference voltage changes, making it difficult to achieve accurate and flexible VFS settings, especially in applications requiring precise temperature sensing and multi-channel ADCs.
Innovation Solution
The proposed solution involves a novel circuit system that automatically tunes the VFS by adjusting the input capacitance of the SAR ADC through a controlled adjusting capacitor array, allowing for digital and programmable tuning of the VFS, thereby reducing sensitivity to temperature and enabling finer tuning steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual tuning of full-scale voltage is performed by adjusting reference voltages, then VFS can be adjusted, but the process is tedious and difficult to re-adjust when system requirements change
Solution Approach 1:
The patent replaces manual mechanical adjustment of reference voltages with an automated digital control system. A tuning control unit generates capacitor tuning codes that automatically adjust the equivalent capacitance of the CDAC, eliminating the need for manual intervention and making VFS tuning flexible and easy to re-adjust for different system requirements
Solution Approach 2:
The system enables self-service by allowing the tuning control unit to automatically generate capacitor tuning codes based on system requirements. The CDAC and comparator can be re-optimized automatically without requiring manual intervention, making the system self-configurable for different VFS requirements
2Adaptability or versatility
If CDAC capacitance or reference voltage is manually optimized to meet new system requirements, then VFS can be adjusted, but the process is complex and time-consuming
Solution Approach 1:
The patent implements preliminary action by pre-configuring the adjusting capacitor array and tuning control unit to enable rapid VFS adjustment. When system requirements change, the tuning control unit can immediately generate appropriate capacitor tuning codes without requiring time-consuming manual re-optimization of CDAC capacitance or reference voltages
Solution Approach 2:
The system introduces dynamics by making the VFS可调 through digital control of the adjusting capacitor array. The VFS can be dynamically adjusted by changing capacitor tuning codes, allowing the system to adapt quickly to different requirements without fixed manual optimization
3Measurement precision
If manual VFS tuning is performed, then VFS can be set, but the process is tedious and lacks precision
Solution Approach 1:
The patent replaces manual VFS tuning with automated digital control. The tuning control unit generates precise capacitor tuning codes that control the adjusting capacitor array, achieving accurate VFS settings without the tedium and imprecision of manual adjustment
Solution Approach 2:
The system achieves precise VFS tuning by changing the equivalent capacitance parameter of the CDAC through digital control. The tuning control unit adjusts capacitor tuning codes to modify the equivalent capacitance, providing precise and programmable VFS tuning steps
Data Source
AI summary
An SAR ADC includes: at least one sub-ADC, configured to convert a corresponding input signal to a corresponding SAR code; and a tuning control unit, configured to adjust a full-scale voltage (VFS) of each of the sub-ADC to a corresponding predetermined target level in a VFS tuning mode. The tuning control unit generates a tuning code to control an adjusting capacitor array coupled to the sub-ADC for tuning the VFS. The tuning control unit controls the sub-ADC to convert plural reference voltages in the VFS tuning mode and extrapolating the conversion result to determine a corresponding calibrating VFS. The tuning control unit determines whether the calibrating VFS meeting the target VFS and loops the adjusting process in a linear search method or in a SAR method.