The measurement setup is based on a PXI Chassi (PXIe-1082) with embedded host PC from National Instruments. The chassis is equipped with a Vector Signal Transciver (PXIe-5646R VST) with 200 MHz instantaneous bandwidth. The signal generated from the VST transmitter is fed to a linear driver amplifier before the GaN PA DUT (Cree CGH40006-TB, testboard for the transistor CGH40006P). A 30 dB RF attenuator is placed at the DUT output from which the output signal is connected to the VST receiver. A PC embedded in the PXI chassi is used to control the instruments and to down- and upload datafiles at request from the users. The DUT is suppled by a power source module (PXI-4130) which also measures the current consumption of the power amplifier.
The peak output power level from the PA is limited to approximately 6 W, by putting a restriction on the allowable output power from the signal generator. The settings in the signal analyzer (reference level and input attenuation) are set in a such a way as not to distort the measured signal even for the highest peak power level. This means that you will experience a degradation in noise performance when using power levels lower than the maximum allowable level.
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