Spurious-free dynamic range
Spurious-Free Dynamic Range (SFDR) is a measure used to specify analog-to-digital and digital-to-analog converters (ADCs and DACs, respectively) and radio receivers.
SFDR is defined as the ratio of the RMS value of the carrier frequency (maximum signal component) at the input of the ADC or DAC to the RMS value of the next largest noise or harmonic distortion component (which is referred to as a “spurious” or a “spur”) at its output. SFDR is usually measured in dBc (i.e. with respect to the carrier frequency amplitude) or in dBFS (i.e. with respect to the ADC's full-scale range). Depending on the test condition, SFDR is observed within a pre-defined frequency window or from DC up to Nyquist frequency of the converter (ADC or DAC).
In case of a radio receiver application, the definition is slightly different. The reference is the minimum detectable signal level at the input of a receiver, which can be calculated through a knowledge of the noise figure and the input signal bandwidth of the receiver or the system. The difference between this value and the input level which will produce distortion products equal to the minimum detectable signal refered to the input of the system is the SFDR of the system.
See also
- Analog-to-digital converter
- Digital-to-analog converter
- THD (Total Harmonic Distortion)
- SINAD (SIgnal-to-Noise-And-Distortion)