ADC Comparator Calibration with Internal DAC Reference Generation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analogue-to-digital converters (ADCs) require dedicated external calibration references for each comparator, leading to increased circuit area, design time, and power consumption, as well as potential comparator errors due to common-mode dependent offset.
Innovation Solution
The proposed ADC uses its internal digital-to-analogue converter (DAC) to generate calibration reference signals, eliminating the need for specific external references and allowing calibration of comparator offsets using a single external zero differential voltage, thereby reducing the complexity and cost of calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated external calibration references are used for each comparator, then calibration precision is improved, but device complexity and circuit area increase
Solution Approach 1:
The patent applies universality by making the internal DAC serve multiple functions: it performs both normal conversion operations and generates calibration reference signals for all comparators. This eliminates the need for dedicated external calibration references, reducing device complexity while maintaining calibration precision through the use of a single multi-functional component.
Solution Approach 2:
The patent merges the calibration reference generation function into the internal DAC structure. By combining the normal operation functionality with the calibration reference generation capability within the same DAC circuit, the patent reduces the total number of components and simplifies the overall system architecture while preserving measurement precision.
2Manufacturing precision
If dedicated external calibration references are used for each comparator, then calibration accuracy is improved, but manufacturing cost and design time increase
Solution Approach 1:
The internal DAC is designed to universally serve both conversion and calibration reference generation purposes. This multi-functionality reduces manufacturing complexity by eliminating the need to source, match, and integrate multiple dedicated external calibration references, thereby easing manufacturing while maintaining calibration accuracy.
Solution Approach 2:
The ADC system performs calibration using its own internal DAC resources without requiring external calibration reference components. This self-service approach simplifies the manufacturing process by reducing the bill of materials and assembly steps, while the internal DAC ensures calibration accuracy through integrated design.
3Measurement precision
If multiple external calibration references are used, then comparator offset calibration is improved, but power consumption increases
Solution Approach 1:
The internal DAC universally provides calibration reference signals to all comparators, eliminating the need for multiple external calibration reference sources. This reduces power consumption by removing the overhead of multiple independent reference circuits while maintaining comparator offset calibration precision through the shared internal DAC resource.
4Adaptability or versatility
If dedicated calibration circuitry is added, then calibration capability is improved, but device complexity increases
Solution Approach 1:
The internal DAC is enhanced to serve dual purposes: normal conversion operations and calibration reference generation. This universal design improves calibration capability without adding dedicated calibration circuitry, thereby avoiding increased device complexity while maintaining full calibration functionality.
Solution Approach 2:
The calibration capability is merged into the existing internal DAC structure rather than being implemented as a separate dedicated circuit. This integration maintains adaptability and calibration versatility while avoiding the complexity overhead of additional independent calibration hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the calibration process, reduces the number of external references required, and minimizes comparator errors by using the internal DAC to generate calibration signals, resulting in a more efficient and cost-effective ADC implementation.
Implementation Method 1
The circuitry in the digital-to-analogue converter (DAC) is switched under the control signal to generate a calibration reference voltage
Implementation Method 2
The calibration reference voltage generated by the internal DAC is applied to a comparator of the ADC, where it can be used for calibration purposes
Data Source
AI summary
An ADC includes sampling means for sampling an input voltage signal, comparator(s) for receiving the sampled signal, and a DAC including circuitry for generating a search signal approximating the input signal and a calibration signal. The search signal and the calibration signal are to be applied to a comparator. The ADC also includes a search logic block for receiving a comparator output signal, for providing input to the DAC for generating the search signal, and for producing a digital output signal. Further, the ADC includes a calibration logic block for producing a control signal to control the circuitry of the DAC and including processing means for observing the output signal, for comparing the output signal with a desired output, and for compensating analog non-idealities of the ADC. The DAC circuitry is adapted for generating the calibration signal in accordance with the control signal and with the sampled input signal.