Analog-to-Digital Conversion › lesson 56 of 100 · Advanced
Analyze ADC Nonlinearity Compensation
This lesson is part of a series on Analog-to-Digital Conversion, and after completing it, learners will be able to correct ADC output errors from nonlinear behavior. The lesson fits between designing Sigma-Delta ADC Systems and implementing Digital Calibration Techniques.
Correcting ADC output errors from nonlinear behavior involves compensating for the nonlinear transfer function of the ADC.
In a real-world example, a 12-bit ADC is used to measure the voltage of a signal, but the output codes are not linearly related to the input voltage, resulting in significant errors. This is due to the nonlinear transfer function of the ADC, which can be caused by various factors such as component tolerances and circuit imperfections. To correct these errors, nonlinearity compensation techniques can be applied.
One common method of nonlinearity compensation is to use a lookup table that maps the nonlinear output codes to the correct linear codes. This lookup table can be generated using a calibration procedure, where the ADC is stimulated with a set of known input signals and the corresponding output codes are measured.
Another approach is to use digital calibration techniques, which involve adjusting the digital output of the ADC to compensate for the nonlinearity. This can be done using algorithms that model the nonlinear behavior of the ADC and correct for it in real-time.
Примери
- A 10-bit ADC has a nonlinear transfer function that can be modeled using a third-order polynomial.This is an example of a nonlinear transfer function that can be compensated using a lookup table or digital calibration.
- A Sigma-Delta ADC is used in an audio application, where nonlinearity can cause distortion and affect sound quality.This is an example of an application where nonlinearity compensation is critical to ensure high sound quality.
- A calibration procedure is used to generate a lookup table for a 12-bit ADC, which is then used to correct for nonlinearity.This is an example of a calibration procedure that can be used to generate a lookup table for nonlinearity compensation.
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