Oscillator Sensor Interface Tuning for Mismatch Compensation
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Solution Overview
Problem
Oscillator-based sensor interfaces face accuracy limitations due to mismatch errors between controlled oscillators, which can result in offset, gain, and non-linearity issues, affecting signal conversion and requiring compensation methods that are not fully effective over time and temperature variations.
Innovation Solution
The proposed solution involves an oscillator-based sensor interface circuit that employs chopping techniques to reduce offset and low-frequency noise, combined with online tuning of oscillator parameters to compensate for mismatches, ensuring improved accuracy and robustness against errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two controlled oscillators are used in a closed-loop sensor interface circuit, then the interface can achieve time-based conversion with improved scalability and noise immunity, but mismatch errors between the oscillators cause offset, gain, and non-linearity issues that degrade measurement precision
Solution Approach 1:
The patent implements a feedback mechanism where the output of one oscillator is fed back to adjust the input of the other oscillator, creating a closed-loop system that automatically compensates for mismatch errors. This feedback loop continuously monitors and corrects offset, gain, and non-linearity issues, maintaining measurement precision while preserving the noise immunity benefits of time-based conversion.
Solution Approach 2:
The patent dynamically adjusts oscillator parameters such as frequency, duty cycle, or phase to compensate for mismatch errors. By changing these parameters in real-time based on detected errors, the system maintains accurate measurements despite inherent oscillator variations, directly addressing the precision problem while keeping the time-based conversion architecture intact.
2Measurement precision
If oscillator parameters are tuned to compensate for mismatches, then measurement accuracy is improved, but the device complexity increases due to additional tuning elements and control mechanisms
Solution Approach 1:
The patent combines the tuning elements directly within the oscillator circuits themselves, merging the compensation functionality into the existing structure. By integrating capacitors, resistors, or varactors as part of the oscillator design rather than adding separate external tuning circuits, the patent reduces overall device complexity while still achieving accurate mismatch compensation.
Solution Approach 2:
The patent implements self-tuning mechanisms where the oscillators automatically adjust their own parameters to compensate for mismatches without requiring external control circuits. This self-service approach eliminates the need for complex external tuning equipment, reducing device complexity while maintaining measurement accuracy through autonomous error correction.
3Measurement precision
If chopping techniques are applied to reduce offset and low-frequency noise, then measurement accuracy is improved, but the device complexity increases due to additional chopping circuitry
Solution Approach 1:
The patent implements chopping techniques by periodically switching the oscillator inputs or outputs at a specific frequency to modulate offset and low-frequency noise to higher frequencies where they can be filtered out. This periodic action is achieved through simple switching circuits integrated into the oscillator path, providing accuracy improvement with minimal added complexity compared to continuous correction methods.
Data Source
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AI summary
The present invention relates to an oscillator-based sensor interface circuit comprising - at least two oscillators (21,22), at least one of which is arranged for receiving an electrical signal representative of an electrical quantity, said electrical quantity being a converted physical quantity (100), - phase detection means (3) arranged to compare output signals of said at least two oscillators and for outputting a digital phase detection output signal in accordance with the outcome of said comparing, said phase detector output signal also being an output signal of said oscillator-based sensor interface circuit, - a feedback element (4) arranged for converting a representation of said digital phase detection output signal into a feedback signal used directly or indirectly to maintain a given relation between oscillator frequencies of said at least two oscillators, - means for detecting an error in said given relation between oscillator frequencies of said at least two oscillators based on said digital phase detection output signal, - at least one tuning element (7) arranged for tuning at least one characteristic of the oscillator-based sensor interface circuit causing a change in oscillator frequency of at least one of said oscillators to reduce said detected error.