Analog-to-Digital Conversion › lesson 80 of 100 · Expert

Develop ADC Noise Shaping Techniques

This lesson is part of the Analog-to-Digital Conversion course and will teach you how to apply noise shaping to improve ADC signal quality. After this lesson, you will be able to develop techniques to reduce noise in analog-to-digital converters.

Apply noise shaping to improve ADC signal quality by reducing the noise in the signal band.

In a real-world example, a sigma-delta ADC is used to convert an analog audio signal to a digital signal. The ADC uses noise shaping to push the noise out of the signal band, resulting in a higher signal-to-noise ratio. This is achieved by using a feedback loop to shape the noise spectrum.

The noise shaping technique works by using a filter to attenuate the noise in the signal band, while amplifying the noise in the out-of-band frequencies. This results in a lower noise floor in the signal band, improving the overall signal quality.

The order of the noise shaping filter determines the amount of noise attenuation that can be achieved. A higher order filter can provide more noise attenuation, but also increases the complexity of the ADC.

Examples

• A sigma-delta ADC with a 2nd order noise shaping filterThis ADC can achieve a higher signal-to-noise ratio than a 1st order filter
• A delta-sigma ADC with a 3rd order noise shaping filterThis ADC can achieve an even higher signal-to-noise ratio than a 2nd order filter
• A multi-bit sigma-delta ADC with a 4th order noise shaping filterThis ADC can achieve a very high signal-to-noise ratio

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