Analog-to-Digital Conversion › lesson 55 of 100 · Advanced

Design Sigma-Delta ADC Systems

This lesson is part of the Analog-to-Digital Conversion course, and after completing it, you will be able to design oversampling ADCs with noise shaping. The lesson focuses on the design of Sigma-Delta ADC systems, a crucial aspect of analog-to-digital conversion.

Designing Sigma-Delta ADC systems involves oversampling and noise shaping to achieve high accuracy and resolution.

In a real-world application, such as audio processing, a Sigma-Delta ADC is used to convert analog audio signals into digital signals. The oversampling technique is used to sample the signal at a rate much higher than the Nyquist rate, which helps to reduce the quantization noise. The noise shaping technique is then used to shape the noise spectrum, pushing the noise to higher frequencies where it can be easily filtered out.

The Sigma-Delta ADC consists of an integrator, a quantizer, and a feedback loop. The integrator accumulates the input signal, and the quantizer converts the accumulated signal into a digital signal. The feedback loop then subtracts the quantized signal from the input signal, creating an error signal that is fed back into the integrator.

The order of the Sigma-Delta ADC determines the number of integrators used in the system. A higher-order Sigma-Delta ADC can achieve better noise shaping and higher resolution, but it also increases the complexity of the system.

The oversampling ratio (OSR) is the ratio of the sampling frequency to the Nyquist rate. A higher OSR can improve the accuracy of the conversion, but it also increases the amount of data that needs to be processed.

Tusaalooyin

• A first-order Sigma-Delta ADC with an OSR of 64This is a simple example of a Sigma-Delta ADC with a low OSR.
• A second-order Sigma-Delta ADC with an OSR of 128This is an example of a Sigma-Delta ADC with a higher OSR and better noise shaping.
• A third-order Sigma-Delta ADC with an OSR of 256This is an example of a high-order Sigma-Delta ADC with excellent noise shaping and high resolution.

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