Analog-to-Digital Conversion › lesson 21 of 100 · Beginner

Understand Successive Approximation ADC

This lesson is part of the Analog-to-Digital Conversion course and will teach you about the successive approximation ADC operation. After this lesson, you will be able to understand and explain how successive approximation ADC works.

The successive approximation ADC operation is a method of converting an analog signal to a digital signal by iteratively comparing the analog input to a series

In a real-world application, such as a digital multimeter, a successive approximation ADC is used to convert the analog voltage from a sensor to a digital signal that can be processed by a microcontroller. This type of ADC uses a binary search algorithm to find the digital representation of the analog input. The algorithm starts by comparing the analog input to a reference voltage that is half of the maximum possible voltage, and then iteratively compares the input to reference voltages that are half of the remaining range.

The successive approximation ADC operation involves several key components, including a comparator, a digital-to-analog converter (DAC), and a successive approximation register (SAR). The comparator compares the analog input to the reference voltage, and the DAC converts the digital output from the SAR to an analog signal that can be compared to the input. The SAR stores the digital representation of the analog input and controls the comparison process.

The successive approximation ADC operation is a serial process, meaning that each bit of the digital output is determined one at a time. This process is repeated until all bits of the digital output have been determined, resulting in a digital signal that represents the original analog input.

Exemple

• A successive approximation ADC is used in a digital thermometer to convert the analog voltage from a temperature sensor to a digital signal.The ADC uses a binary search algorithm to find the digital representation of the analog input.
• A successive approximation ADC is used in an audio digitizer to convert the analog audio signal to a digital signal.The ADC uses a comparator and a DAC to compare the analog input to a series of reference voltages.
• A successive approximation ADC is used in a medical device to convert the analog signal from a sensor to a digital signal.The ADC uses a SAR to store the digital representation of the analog input and control the comparison process.

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