N.3 External Amplifiers Uncertainty Terms

37.5443GPPConformance testingRelease 16TSUniversal Terrestrial Radio Access (UTRA) and Evolved UTRA (E-UTRA)User Equipment (UE) Over The Air (OTA) performance

Any components in the setup can potentially introduce measurement uncertainty. It is then needed to determine the uncertainty contributors associated with the use of such components. For the case of external amplifiers, the following uncertainties should be considered but the applicability is contingent to the measurement implementation and calibration procedure.

N.3.1 Stability

An uncertainty contribution comes from the output level stability of the amplifier. Even if the amplifier is part of the system for both measurement and calibration, the uncertainty due to the stability shall be considered. This uncertainty can be either measured or determined by the manufacturers’ data sheet for the operating conditions in which the system will be required to operate.

N.3.2 Linearity

An uncertainty contribution comes from the linearity of the amplifier since in most cases calibration and measurements are performed at two different input/output power levels. This uncertainty can be either measured or determined by the manufacturers’ data sheet.

N.3.3 Noise Figure

When the signal goes into an amplifier, noise is added so that the SNR at the output is reduced with regard to the SNR of the signal at the input. This added noise introduces error on the signal which affects the Error Rate of the receiver thus the EVM (Error Vector Magnitude). An uncertainty can be calculated through the following formula:

where SNR is the signal to noise ratio in dB at the signal level used during the sensitivity measurement.

N.3.4 Mismatch

If the external amplifier is used for both stages, measurement and calibration the uncertainty contribution associated with it can be considered systematic and constant -> 0dB. If it is not the case, the mismatch uncertainty at its input and output shall be either measured or determined by the method described in [3].

N.3.5 Gain

If the external amplifier is used for both stages, measurement and calibration the uncertainty contribution associated with it can be considered systematic and constant -> 0dB. If it is not the case, this uncertainty shall be considered.

Annex O (normative): Environmental conditions