Digital Switchpoint Interpolation for Low-Jitter Magnetic Sensors
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Solution Overview
Problem
Magnetic field sensors face sampling errors due to non-deterministic timing of threshold crossings in high-speed applications, particularly in systems like anti-lock braking systems, where precise timing is critical and analog signal sampling introduces errors between discrete samples.
Innovation Solution
A digitally-computed delay count is determined using a ratio of differences between current and previous sample signal values and a switchpoint threshold, allowing for a switchpoint signal to be generated based on this count, thereby reducing sampling errors by ensuring consistent timing of output signal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If analog signal sampling is performed at discrete time intervals, then the sampling process is simple and straightforward, but non-deterministic sampling error is introduced and timing accuracy is degraded
Solution Approach 1:
The patent replaces the analog sampling mechanism with a digital signal processing approach. Instead of sampling an analog signal at discrete intervals and dealing with threshold crossing timing errors, the system converts the signal to digital form and uses digital interpolation to precisely determine timing. This substitution of digital processing for analog sampling eliminates the fundamental limitation of discrete time sampling while maintaining operational simplicity through algorithmic computation.
Solution Approach 2:
The patent applies preliminary action by performing digital interpolation calculation before the final timing determination is made. The system pre-computes the interpolated timing value based on surrounding digital samples, allowing the exact timing to be determined in advance rather than waiting for the next discrete sample. This preliminary computation ensures timing accuracy is achieved without requiring higher sampling rates.
2Measurement precision
If the sampling rate is increased to reduce sampling error, then timing accuracy improves, but the complexity and resource requirements of the system increase
Solution Approach 1:
The patent uses digital interpolation to create a virtual representation of the signal between actual sample points. Instead of taking more physical samples at higher rates, the system computes interpolated values that copy the behavior of what would have been sampled at intermediate time points. This mathematical copying approach achieves the timing precision of high-rate sampling without the hardware complexity and resource consumption of actually running at higher sampling rates.
3Measurement precision
If digital signal processing is used instead of analog sampling, then sampling error is reduced and timing accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent applies partial action by using a simplified digital interpolation approach that computes only the specific timing information needed, rather than performing full signal reconstruction or processing the entire signal waveform. The system calculates the interpolated timing point using a focused computational method that processes minimal data (just the relevant sample points and their values) to achieve the timing precision goal without unnecessary computational overhead.
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
The proposed solution minimizes jitter and non-deterministic errors in magnetic field sensor outputs, improving timing accuracy and reducing latency, enhancing the reliability of systems that rely on precise magnetic field detection.
Implementation Method 1
Magnetic field sensors including a magnetic field sensing element, or transducers, such as a Hall Effect element
Implementation Method 2
Magnetic field sensors including a magnetic field sensing element, or transducers, such as a Hall Effect element or a magnetoresistance element
Data Source
AI summary
A sensor is provided to include: a sampling clock circuit generating a sample clock signal with a predetermined sample clock period; a system clock circuit generating a system clock signal with a predetermined system clock period, wherein a value of the system clock period is less than a value of the sample clock period; a sensor circuit generating, during each sample clock period, a sensor signal representing a position of an object; a sampling circuit receiving the sensor signal and generate sample signal value in response; an interpolation circuit determining a first difference between a current sample signal and a previous sample signal, determining a second difference between a switchpoint threshold value and the previous sample signal, and determining a delay count based upon a ratio of the first difference and the second difference; and a switchpoint signal circuit generating a switchpoint signal based upon the delay count.