ADC Guide, Part 5: ADC non-linearity (DNL/INL) and monotonic transfer function

Analog-to-digital converters (ADCs) are one of the most commonly used blocks in embedded systems. Applications of ADCs include current sensing, motor control, temperature sensing and a myriad of others. As a consequence, understanding the basic specifications of an ADC and selecting an appropriate device for the given application is a must for reliable operation and cost-effective design.

This series of articles begins with the basics of ADCs, and then discusses different characteristics of an ADC that are important to design, including the impact of various irregularities, types of ADCs available on the market, advantages and disadvantages of each type, and how their selection varies from application to application.

The first part of this article series discusses what exactly an ADC is and how an ideal ADC works. The second part explores the “simple” specification of sample rate, along with the considerations that affect selecting the converter to match your needed rate, such as the Nyquist rate, undersampling, and aliasing. The third part looks at offset errors and calibration, and the fourth part looks at gain error and drift in that error.

This fifth part is a look at two related and sometimes confused nonlinearities in the transfer function, differential and integral:

Part 1: the ideal analog/digital converter

Part 2: the sampling rate

Part 3: offset error

Part 4: gain error and gain error drift

Part 5: ADC non-linearity (DNL/INL) and monotonic transfer function

Subsequent articles will continue exploring various aspects and parameters of the ADC.

About the authors

Sachin Gupta is a Senior Applications Engineer in the Global Applications team at Cypress Semiconductor Corp. He can be reached at .

Akshay Phatak is an Applications Engineer with Cypress Semiconductor. He holds a Bachelor's degree in Electronics and Telecommunications form College of Engineering, Pune (India). He likes to work on mixed-signal embedded systems. He can be reached at .

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