Analog-to-Digital Conversion › lesson 34 of 100 · Intermediate

Describe ADC Calibration Methods

This lesson is part of the Analog-to-Digital Conversion course and will teach methods to calibrate ADCs for improved accuracy. After this lesson, the learner will be able to describe and apply ADC calibration methods to achieve more accurate digital representations of analog signals.

ADC calibration methods are used to improve the accuracy of analog-to-digital converters by correcting for errors and non-idealities in the conversion process.

In a real-world example, a medical device manufacturer uses ADCs to convert analog signals from sensors into digital data that can be processed and analyzed. To ensure the accuracy of this data, the manufacturer must calibrate the ADCs using methods such as gain adjustment and offset correction. These methods involve adjusting the ADC's transfer function to match the ideal transfer function, which is a straight line. By doing so, the ADC's accuracy can be improved, and the device can provide more reliable results.

The gain adjustment method involves adjusting the ADC's gain to match the ideal gain, which is the ratio of the output code to the input voltage. This can be done by applying a known input voltage and adjusting the gain until the output code matches the expected value. The offset correction method involves adjusting the ADC's offset to match the ideal offset, which is the output code when the input voltage is zero. This can be done by applying a zero input voltage and adjusting the offset until the output code is zero.

Another method is linearity correction, which involves adjusting the ADC's transfer function to match the ideal transfer function over the entire range of input voltages. This can be done by applying a series of known input voltages and adjusting the transfer function until the output codes match the expected values.

Esempi

• A 12-bit ADC has a gain error of 0.5% and an offset error of 1 LSB. To calibrate this ADC, the gain adjustment method can be used to adjust the gain, and the offset correction method can be used to adjust the offset.This example illustrates the use of gain adjustment and offset correction to calibrate an ADC.
• A medical device uses an ADC to convert analog signals from a sensor into digital data. The ADC has a non-linearity error of 1% over the range of input voltages. To calibrate this ADC, the linearity correction method can be used to adjust the transfer function.This example illustrates the use of linearity correction to calibrate an ADC.
• An ADC has a resolution of 16 bits and a sampling rate of 100 kSPS. To calibrate this ADC, the gain adjustment method can be used to adjust the gain, and the offset correction method can be used to adjust the offset.This example illustrates the use of gain adjustment and offset correction to calibrate an ADC.

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