Internal Reference ADC Calibration Without External Pins
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Solution Overview
Problem
Analog-to-digital converters (ADCs) face challenges in calibration due to limited external pins, which restrict their ability to receive necessary reference signals for accurate calibration, especially in systems with size and cost constraints.
Innovation Solution
The ADC system generates internal reference signals to enable self-calibration, using bandgap voltage generation circuits to produce stable reference voltages that can be applied internally for calibration purposes, allowing for accurate digital output conversion without external references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external reference pins are used for ADC calibration, then calibration accuracy is improved, but device complexity and pin quantity increase
Solution Approach 1:
The ADC system performs self-calibration by generating its own internal reference voltages using bandgap voltage generation circuits. The system measures these internally generated reference voltages through an external pin and uses the measurements to calculate calibration values, eliminating the need for external reference pins while maintaining calibration capability
Solution Approach 2:
The calibration function is extracted from requiring external reference sources and moved into the ADC system itself. The bandgap voltage generation circuits are integrated within the ADC system to produce the necessary reference voltages internally, separating the calibration function from external hardware dependencies
2Measurement precision
If external reference signals are provided for calibration, then ADC accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The ADC system generates its own reference voltages internally through integrated bandgap voltage generation circuits, eliminating the need for external reference components. This self-sufficient approach reduces component count and assembly complexity, thereby lowering manufacturing costs while maintaining calibration accuracy
3Device complexity
If internal reference voltages are generated for calibration, then device complexity is reduced, but calibration precision may be affected
Solution Approach 1:
The patent replaces external physical reference voltage sources with internally generated electronic reference voltages using bandgap circuits. This substitution maintains precision through careful electronic design of the reference generation and measurement process, achieving accurate calibration without external hardware
Solution Approach 2:
An external voltage measurement device serves as an intermediary to measure the internally generated reference voltages. The system uses these measurements to calculate calibration values, creating a bridge between internal reference generation and external calibration verification without requiring permanent external reference connections
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 enhances the accuracy and precision of ADC systems by enabling calibration within the ADC itself, improving the consistency and reliability of digital output signals, even in resource-constrained environments.
Implementation Method 1
using bandgap voltage generation circuits to produce stable reference voltages that can be applied internally for calibration purposes
Data Source
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AI summary
An analog-to-digital converter (ADC) system for providing a calibrated voltage measurement without an external reference voltage may include an ADC circuit, including an analog ADC input and a digital ADC output. The ADC system may also include circuitry to generate a first internal reference voltage and a second internal reference voltage. The ADC system may also include circuitry configured to provide a selected output from a number of inputs, wherein the inputs include inputs to receive (1) the first internal reference voltage, (2) the second internal reference voltage, and (3) a user-provided analog signal of interest, wherein the selected output can be connected to the analog ADC input, an external voltage measurement device, or both.