Comparator Self-Calibration Circuit for Safety-Critical Systems
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Solution Overview
Problem
Existing data acquisition systems for safety-critical applications require redundant measurement paths, which can be costly and power-consuming, and existing calibration methods for comparators are complex and time-consuming due to accuracy drift over time.
Innovation Solution
An analog front-end circuit with a comparator and a preamplifier that allows self-calibration by adjusting user-definable reference values to tighten comparator specifications, using a programmable data register and a reference voltage buffer to measure and correct measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a comparator is used as a redundant measurement path to reduce cost and power consumption, then cost and power consumption are reduced, but measurement precision deteriorates due to accuracy drift over time
Solution Approach 1:
The patent applies preliminary action by performing calibration of the comparator before actual measurement operations. A calibration routine is executed that determines calibration values representing the accuracy of the comparator at different times, allowing the system to pre-compensate for drift effects before they significantly impact measurement precision.
Solution Approach 2:
The patent implements feedback by continuously monitoring comparator accuracy through calibration routines and using the determined calibration values to adjust subsequent measurements. The system feeds back the accuracy information to compensate for drift, maintaining measurement precision while using the power-efficient comparator architecture.
2Measurement precision
If complex calibration routines with SAR search algorithms are used to maintain comparator accuracy, then measurement precision is maintained, but device complexity and time consumption increase
Solution Approach 1:
The patent extracts the essential calibration function from complex SAR search algorithms and implements a simplified calibration routine. Instead of using elaborate search algorithms, the system uses a streamlined approach that determines calibration values through a less complex process, reducing device complexity while maintaining sufficient accuracy.
Solution Approach 2:
The patent changes the calibration approach from traditional voltage-sweeping methods to a parameter-based calibration that determines accuracy at different times. This allows the system to track drift over time and compensate for it without requiring complex real-time calibration circuitry during operation.
3Measurement precision
If traditional calibration methods sweeping DAC voltages are used to determine comparator accuracy, then measurement precision is maintained, but time consumption increases
Solution Approach 1:
The patent performs calibration actions preliminarily and stores calibration values for later use. Instead of performing time-consuming voltage sweeps before every measurement, the system establishes calibration values in advance and applies them during operation, significantly reducing the time loss associated with repeated calibration.
Solution Approach 2:
The patent implements periodic calibration rather than continuous calibration. The calibration routine is executed at scheduled intervals to determine updated calibration values representing accuracy at different times, allowing the system to maintain precision while minimizing the frequency and total time of calibration operations.
Data Source
AI summary
An analog front-end circuit for self-calibrating a comparator, the circuit comprising a comparator in a comparator measurement path; a preamplifier coupled to the comparator by a set of switches; and an amplifier coupled to the preamplifier, the preamplifier receiving a reference signal as a first input and a user-definable reference as a second input, the user-definable reference generating a user-definable value chosen to create a known condition at an output of the preamplifier, the preamplifier determines a residual value that represents a measurement error in a signal path comprising the comparator and is used to adjust the user-definable reference value to calibrate the signal path such that threshold boundaries for the comparator can be adjusted to tighten a comparator specification.