What is SFDR?

What is Spurious-Free Dynamic Range?

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Editorial Team - everything RF

Oct 6, 2020

The Spurious-Free Dynamic Range (SFDR) of a receiver is a ratio of the amplitude of the fundamental carrier signal to the amplitude of the strongest spurious signal in the frequency range of interest. SFDR is usually measured in dBc (i.e. with respect to the carrier signal amplitude).

Mathematically, it is the dynamic ratio between the root mean square (rms) value of the power of a carrier and the rms value of the next most significant spurious signal seen in the frequency domain.

SFDR is often quantified as the range, in units of power (dBc), with respect to the carrier signal frequency. However, it also could be referenced to a full-scale signal in units of power (dBFS).

In case the next spurious signal falls outside the frequency range of interest, then SFDR can not be calculated. Factors that dominate the SFDR include Noise figure, 2nd and 3rd Order Intercept, 1-dB Compression, Internal Spurs and Bandwidth.