Electrochemical Cell Measurement Circuit With ADC Nonlinearity Compensation
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Solution Overview
Problem
Existing electrochemical sensors suffer from non-ideal effects and sub-optimal circuitry that introduce errors in the measurement of analyte concentrations, leading to non-linearities and inaccuracies in the response signals.
Innovation Solution
The proposed circuitry includes compensation circuits to correct for non-linearity in both the analog-to-digital converter (ADC) and measurement circuitry, using adaptive filters and digital-to-analog converters to apply calibration signals and adjust compensations dynamically, ensuring accurate signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard ADC and measurement circuitry are used without compensation, then device complexity is reduced, but measurement precision deteriorates due to non-linearity errors
Solution Approach 1:
The patent applies preliminary action by pre-calibrating the ADC and measurement circuitry to determine compensation values before actual measurement. The calibration process characterizes non-linearity errors in advance, and these compensation values are stored for use during normal operation, eliminating the need for complex real-time correction algorithms.
Solution Approach 2:
The patent implements feedback by using the calibrated compensation values to correct the digital output signal from the ADC. The compensation circuitry receives the digital signal, applies the pre-determined correction based on the characterized non-linearity, and outputs a corrected signal that compensates for the measured errors.
2Measurement precision
If compensation circuitry is added to correct non-linearity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The compensation values are determined in advance through a calibration process that characterizes the ADC and measurement circuitry. This preliminary characterization allows the system to use simple lookup tables or stored correction factors during normal operation, rather than implementing complex real-time calculation algorithms.
Solution Approach 2:
The patent creates a digital model or copy of the non-linearity characteristics through calibration. This digital representation of the errors is stored and used to generate corrected output signals, replacing the need for complex hardware correction circuits.
3Measurement precision
If calibration is performed frequently to maintain accuracy, then measurement precision is maintained, but productivity decreases due to calibration time
Solution Approach 1:
The calibration is performed in advance during manufacturing or initial setup, creating a permanent or semi-permanent compensation profile. This preliminary calibration eliminates the need for frequent recalibration during normal operation, as the compensation values remain valid over extended periods.
Solution Approach 2:
The system performs self-calibration or self-correction by automatically applying the pre-determined compensation values to the ADC output. This self-service approach maintains measurement precision without requiring external intervention or manual calibration procedures during normal operation.
Data Source
AI summary
Circuitry for processing an analyte signal obtained from an electrochemical cell, the circuitry comprising: measurement circuitry having a first measurement input coupled to a first electrode of the electrochemical cell, the measurement circuitry configured to convert the analyte signal at the first measurement input to a first analog output signal; an analog-to-digital converter (ADC) having an first ADC input for receiving the first analog output signal, the ADC configured to convert the first analog output signal to a first digital output signal at an ADC output; compensation circuitry configured in a measurement mode to: apply a first compensation to the first digital output signal to obtain a first compensated digital output signal, the first compensation to compensate for non-linearity in the ADC; and apply a second compensation to the first compensated digital output signal to obtain a second compensated digital output signal, the second compensation to compensate for non-linearity in the measurement circuitry; control circuitry configured in a calibration mode to: apply a first calibration signal at the first ADC input and adapt the first compensation based on the first calibration signal and the first compensated digital output signal; and apply a second calibration signal at the first electrode and adapt the second compensation based on the second calibration signal and the second compensated digital output signal.