A Novel Experimental Noise Power Ratio Characterization Method for Multicarrier Microwave Power Amplifiers

The linearity characterization of multicarrier power amplifiers in terms of Noise Power Ratio (NPR) is now well adopted. The use of an analog band pass noise source with a notch in the center bandwidth is currently used for this purpose. We present in this paper a novel NPR measurement technique based on a numerical generation of a gaussian noise. This experimental noise generation is similar to the technique used in non linear circuit level or system level simulations using the envelope transient technique. The measurement principle is based on the use of a baseband arbitrary waveform generator (AWG) and an upconverter chain from baseband to L or S band. The large signal Noise stimuli drive the amplifier under test. The output signal of the amplifier is downconverted back to baseband and the resulting complex envelope is recorded with a sampling scope and computed for NPR extraction. A comparison of NPR measurements obtained with our method and with the conventional analog noise source technique is presented. Other possible applications of our measurement system are also mentioned and emphasize the capabilities of the proposed characterization tool.