Feedforward Current Sensor for Linear Current-to-Frequency Conversion
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Solution Overview
Problem
Current sensors with current-controlled oscillators face non-linearities in current-to-frequency conversion, which affect the accuracy of charge quantization and frequency output.
Innovation Solution
A current sensor design that incorporates a feedforward circuit to adapt the reference voltage of the current-controlled oscillator based on the instantaneous current value, introducing a linear or quasi-linear decay factor to render the frequency-current relation linear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current-controlled oscillator is used for charge quantization, then the output frequency is dependent on the input current, but non-linearities occur in the current-to-frequency conversion
Solution Approach 1:
The patent applies feedback by using a feedforward circuit that continuously monitors the instantaneous current value and adjusts the reference voltage of the current-controlled oscillator accordingly. This closed-loop approach compensates for non-linearities in real-time, improving the linearity of current-to-frequency conversion while maintaining charge quantization accuracy.
Solution Approach 2:
The patent changes the reference voltage parameter dynamically based on the instantaneous current value. By adjusting this parameter through the feedforward circuit, the system compensates for non-linear effects and maintains linear current-to-frequency conversion across different operating conditions.
2Manufacturing precision
If the reference voltage is adapted based on instantaneous current value, then the frequency-current relation becomes linear, but additional circuit complexity is introduced
Solution Approach 1:
The patent introduces a feedforward circuit as an intermediary element that mediates between the input current and the reference voltage of the current-controlled oscillator. This intermediary component simplifies the overall control logic by handling the non-linearity compensation automatically, making the system easier to implement despite the added circuitry.
Data Source
AI summary
Embodiments of the invention are directed to a current sensor that includes a current controlled oscillator circuit configured to receive an input current and to provide an output signal having an output frequency which is dependent on the input current. The current sensor further includes a feedforward circuit configured to adapt a reference voltage of the current controlled oscillator in dependence on an instantaneous current value of the input current.