Nonlinear Converter Circuit for Temperature Sensor Linearization
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Solution Overview
Problem
Existing measurement devices, such as diodes, exhibit non-linear temperature behavior, making accurate temperature measurement difficult due to second-order non-linearity, which necessitates the linearization of non-linear responses.
Innovation Solution
A non-linear converter comprising a non-linear voltage divider, an analog multiplexer, and an analog comparator, along with digital potentiometers, is used to convert non-linear voltage responses into linearized digital outputs, and extend the resolution of digital-to-analog converters (DACs) by adjusting resistor values and switching configurations, thereby correcting for non-linearity in temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-linear voltage divider with multiple resistors is used to match the non-linear transfer function, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The non-linear transfer function is segmented into multiple linear segments, each represented by a resistor in the voltage divider. The analog multiplexer selects the appropriate segment based on the input signal level, effectively breaking down the complex non-linear function into manageable linear portions that can be easily implemented and controlled.
Solution Approach 2:
The converter uses dynamic switching through the analog multiplexer to change the resistance configuration based on the input signal level. This dynamic reconfiguration allows the system to adapt to different operating conditions and maintain accuracy across the full measurement range without requiring a completely complex static circuit.
2Measurement precision
If the number of resistors in the non-linear voltage divider is increased to improve linearity, then measurement precision is improved, but layout area increases
Solution Approach 1:
Instead of using a single complex non-linear element, the transfer function is segmented into multiple simpler linear segments. Each segment can be implemented with a single resistor, reducing the area required per functional unit while achieving the same overall accuracy through the combination of segments.
Solution Approach 2:
The analog multiplexer serves multiple functions: it selects the appropriate resistor segment, it provides signal routing, and it enables the system to achieve high precision across the full measurement range. This multi-functionality reduces the need for additional dedicated components that would increase layout area.
3Manufacturing precision
If digital potentiometers are used for calibration, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The digital potentiometers enable the calibration circuit to self-adjust and self-correct during manufacturing or operation. The system can automatically calibrate itself by measuring reference voltages and adjusting the potentiometer settings to compensate for process variations, eliminating the need for complex external calibration equipment or manual adjustment procedures.
Solution Approach 2:
The digital potentiometers allow dynamic adjustment of resistance values to optimize calibration. By changing the resistance parameters based on measured reference voltages, the system can achieve high manufacturing precision without requiring complex fixed resistor networks or multiple calibration components.
Data Source
AI summary
A non-linear converter comprising a non-linear voltage divider having a plurality of resistors representing a non-linear transfer function, an analog multiplexer having analog multiplexer inputs coupled to the non-linear voltage divider and configured to output an analog multiplexer output, the analog multiplexer chooses one of the plurality of resistors based on a logic signal and the non-linear transfer function, an analog comparator having an analog comparator first input configured to receive an analog input voltage, an analog comparator second input configured to receive the analog multiplexer output and the analog comparator configured to output a comparator voltage output and a logic loop coupled to the analog comparator and configured to receive the comparator voltage output and configured to output the logic signal, wherein the logic signal represents a linearized digital word.