The Spurious Free Dynamic Range conversion calculator determines the SFDR of an RF receiver using the Third Order Intercept Point (IIP3) and the Minimum Detectable Signal (MDS). SFDR defines the usable dynamic range within which a receiver can process signals without distortion from intermodulation products, making it essential for evaluating receiver performance and linearity.
Formulas
SFDR = (2/3) * (IIP3 – MDS)
If IIP3 is given in watts:
IIP3 (dBm) = 10 * log10(IIP3 * 1000)
Formula Explanation
- IIP3 is the Third Order Intercept Point, representing the power level where third-order distortion products equal the desired signal level.
- MDS is the Minimum Detectable Signal, typically measured in dBm, representing the noise floor of the receiver.
- SFDR quantifies how well a receiver can handle strong signals while still detecting weak ones without spurious interference.
- The factor (2/3) accounts for the cubic relationship between intermodulation distortion and signal level.
Uses of this calculator
- Assessing receiver performance and signal handling capability.
- Designing RF front ends with optimal linearity and sensitivity.
- Comparing different receiver architectures for wide dynamic range applications.
- Determining limits for low-distortion signal reception in radar and communication systems.
What is the SFDR if IIP3 = 10 dBm and MDS = -100 dBm?
Input: IIP3 = 10 dBm, MDS = -100 dBm
Output:
- SFDR = (2/3) * (10 – (-100)) = (2/3) * 110 = 73.33 dB
- Spurious Free Dynamic Range = 73.3 dB