ADC Range Shifting With DAC Offset for Higher Resolution
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Solution Overview
Problem
Analog-to-digital converters (ADCs) often operate with excess resolution and complex circuitry due to fixed span configurations, wasting power and resources, as they are not adaptive to varying input signals, leading to inefficiencies in measuring both large and small signal variations.
Innovation Solution
An automatic range shift system that combines external analog inputs and DAC outputs to dynamically adjust the ADC input, using a control circuit to detect range limits and generate adjustment codes to keep the signal within a reduced span, thereby utilizing coarser ADCs for higher resolution and lower power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution ADC is used to cover the full span, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements dynamic range shifting by automatically adjusting the DAC offset based on the input signal level. The system transitions from a static full-span configuration to a dynamic sub-span configuration, where the ADC operates on a reduced range that adapts to the actual signal variations. This allows using a lower-resolution ADC while maintaining measurement precision for the actual signal range.
Solution Approach 2:
The patent changes the operating parameters of the ADC system by introducing a programmable DAC that dynamically adjusts the input offset. This parameter change enables the system to switch between full-span and sub-span modes, effectively reducing the required ADC resolution while maintaining measurement accuracy for the actual signal range.
2Measurement precision
If a high-resolution ADC is used to cover the full span, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the operating range of the ADC by changing the DAC offset in response to signal level changes. This dynamic adaptation allows the use of a lower-resolution, lower-power ADC while maintaining measurement precision for the actual signal range, directly reducing power consumption.
Solution Approach 2:
By changing the operating parameters through programmable DAC offset adjustment, the system enables a lower-resolution ADC to achieve the required measurement precision, thereby reducing the power consumption associated with high-resolution ADC operation.
3Device complexity
If the ADC span is reduced to match short-term signal variations, then device complexity is reduced, but adaptability to large signal variations worsens
Solution Approach 1:
The patent introduces a programmable DAC as an intermediary component between the input signal and the ADC. This DAC dynamically adjusts the input offset to center the actual signal range within the ADC's sub-span, enabling the system to handle both small short-term variations and large long-term variations while maintaining a low-complexity ADC design.
Solution Approach 2:
The system dynamically adapts to different signal ranges by automatically adjusting the DAC offset based on signal level detection. This dynamic adjustment maintains the signal within the optimal sub-span range, providing both reduced device complexity and enhanced adaptability to varying signal conditions.
4Ease of operation
If a fixed DAC offset is used, then ease of operation is improved, but adaptability to varying signal ranges worsens
Solution Approach 1:
The system implements self-service by automatically detecting signal levels and adjusting the DAC offset without requiring manual intervention. The control circuit autonomously manages the range shifting operation, maintaining ease of operation while providing adaptive response to varying signal ranges.
Solution Approach 2:
The patent incorporates feedback mechanisms where the ADC output or signal level information is used to automatically adjust the DAC offset. This feedback loop enables the system to adapt to varying signal ranges while maintaining simple operation, as the adjustment process is automatic and transparent to the user.
Data Source
AI summary
Automatic range shifting for an analog to digital converter (ADC) includes combining an external analog input and a DAC output to provide an input to the ADC, detecting whether the range of the output of the ADC is above a predetermined upper range limit or below a predetermined lower range limit, and generating an adjustment code to increase the DAC output if the ADC output is above the upper range limit and to decrease the DAC output if the ADC output is below the lower range limit for decreasing the ADC input when the ADC output is above the upper limit and to increase the ADC input when the ADC output is below the lower limit to keep the ADC input within the ADC range.