This calculator determines the gain uncertainty, also called gain ripple, caused by impedance mismatches between components such as amplifiers, sources, and loads. It accounts for reflections and isolation effects to estimate the minimum and maximum possible gain.
Formulas
P = 10^((-RLs – RLi)/20) + 10^((G – RLl – RLs – ISO)/20) + 10^((-RLo – RLl)/20)
Gmin = 20 * log10(1 – P)
Gmax = 20 * log10(1 + P)
Formula Explanation
- RLs, RLi, RLo, RLl are the source, input, output, and load return losses in dB.
- G is the amplifier gain in dB.
- ISO is the reverse isolation (in dB).
- P represents the combined effect of all reflection paths on gain variation.
Example
Input: RLs = 20 dB, RLi = 18 dB, RLo = 20 dB, RLl = 15 dB, G = 10 dB, ISO = 30 dB
Result: Gmin ≈ 9.92 dB, Gmax ≈ 10.08 dB
Who uses it
Helps RF engineers assess amplifier stability and predict gain variation in systems where impedance mismatch may affect performance.