ADC Spurious Free Dynamic Range

Spurious Free Dynamic Range (SFDR) is the ratio of the level of the input signal to the level of the largest distortion component in the Fast Fourier Transforms (FFT) spectrum. This specification is important because it determines the minimum signal level that can be distinguished from distortion components. Label B in the figure below shows the SFDR Analog-to-Digital Converter (ADC) measurement data.

adc-fft.PNG

The FFT spectrum obtained from the ADC will have a noise floor that is a function of N, data resolution in bits, and M, the number of points in the FFT data. For a set of M-point FFT data, the level of the FFT noise floor can be determined using the equation below, where N is the resolution of the ADC in bits.

(1)
\begin{equation} FFT Noise Floor = 6.02 • N +1.76 dB - log (M/2) \end{equation}
© 2024 Microchip Technology, Inc.
Notice: ARM and Cortex are the registered trademarks of ARM Limited in the EU and other countries.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.