Fig. 2. Measured small-signal performance of ZX60-83LN-S+ amplifier. (a) Small signal-gain S21 Uncertainty in S11 and S22 . ; (b) Uncertainty in small-signal gain S21 ; (c) S11 and S22 ; and (d) using (4) and the uncertainty in the P1dB , u(P1dB ), was calculated using (6) from the measured data. The measurement uncertainties in these large-signal parameters of the amplifier are plotted in Fig. 5. The plot also includes uncertainties in small-signal gain, u(SSS21 large-signal gain, u(LSS21), where LSS21 ), from Fig. 2b and uncertainties in = B2/A1 . The results show that for the power dependent amplifier measurements, u(POUT) is between 0.07 and 0.09 dB. u(PIN ) is dependent on the input return loss of the amplifier as well as the uncertainties in the available power from the source. This results in slightly higher u(PIN ) at frequencies for which the input return loss of the DUT is higher. The measurement uncertainty in LSS21 (measured with both a vector calibration and a power calibration) is between 0.1 and 0.12 dB whereas the uncertainty in SSS21 (measured with only a vector calibration) was only 0.025 to 0.045 dB. The main reason for the higher uncertainty in LSS21 compared to SSS21 Fig. 3. Measured POUT versus PIN of the amplifier. September 2022 the uncertainty contribution from the power meter. IEEE Instrumentation & Measurement Magazine 41 is due to