Ratiometric ADC Circuit Without Level Shifters Across Voltage Ranges
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Solution Overview
Problem
Conventional ratiometric analog-to-digital conversion circuits, such as SAR ADCs, face challenges in high-speed operation and design area due to the need for level shifters and accuracy maintenance across different voltage ranges, particularly when converting high to low voltage ranges.
Innovation Solution
A ratiometric analog-to-digital conversion circuit that operates using separate voltage ranges with a first power supply voltage for the high voltage range and a second power supply voltage for the low voltage range, eliminating the need for level shifters by performing feedback within the same voltage range and using monitoring information to compensate for reference voltage errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a level shifter is used to transfer signals between different voltage ranges in a SAR ADC, then the conversion between high voltage range input signals and low voltage range digital outputs is enabled, but the chip area increases and high-speed operation becomes difficult to implement
Solution Approach 1:
The patent extracts and removes the level shifter component from the SAR ADC architecture. By operating both the SAR analog part and SAR digital part at the same low voltage range, the patent eliminates the need for level shifting circuitry, thereby reducing chip area while maintaining the ability to transfer signals between voltage ranges through a different approach (using the same voltage range for both parts).
Solution Approach 2:
The patent changes the voltage range parameter for the SAR digital part from a traditionally different voltage range to the same low voltage range as the SAR analog part. This parameter change eliminates the voltage range mismatch that necessitates level shifters, thus reducing chip area while enabling high-speed operation.
2Ease of operation
If a level shifter is used to transfer signals between different voltage ranges in a SAR ADC, then voltage range conversion is achieved, but the operation speed is limited
Solution Approach 1:
By removing the level shifter component and operating both SAR parts at the same voltage range, the patent eliminates the speed limitations inherent in level shifting operations. The signal transfer between voltage ranges is achieved through the unified voltage range operation, enabling high-speed conversion without the bottlenecks of level shifting circuitry.
3Use of energy by stationary object
If a reference voltage of low level is used in the second voltage range for analog-to-digital conversion, then power consumption is reduced, but conversion accuracy deteriorates due to conversion errors
Solution Approach 1:
The patent employs a monitoring circuit that provides feedback information about the actual reference voltage level to the calculation circuit. The calculation circuit uses this feedback to compensate for any deviations or errors in the low-level reference voltage, thereby maintaining high conversion accuracy despite using a low-power reference voltage in the second voltage range.
Solution Approach 2:
The patent makes the second voltage range operation circuit capable of handling both the analog-to-digital conversion and the reference voltage monitoring functions. By integrating these functions, the circuit can effectively use the low-level reference voltage for conversion while simultaneously monitoring and compensating for accuracy errors, achieving both low power consumption and high precision.
Data Source
AI summary
A ratiometric analog-to-digital conversion circuit includes a first voltage range operation circuit configured to use a first power supply voltage of a first voltage range, and output an analog signal corresponding to an external input signal; and a second voltage range operation circuit configured to use a second power supply voltage of a second voltage range, generate a digital value by analog-to-digital converting the analog signal, feed back the digital value for analog-to-digital conversion, and output a digital signal corresponding to the digital value and proportional to the input signal.