An error corrected two-tone time domain measurement system has been developed and combined with a low frequency active source and load-pull system to investigate the effects of all impedance terminations, IF and RF, on the linearity and ,efficiency of power transistors. Measured data is presented on a HBT biased in class B stimulated by a two-tone signal while actively load pulling the low frequency IF component.
An analysis technique has been developed that allows for the determination of the transistor dynamic IN characteristics (RFI-V) directly from CW large signal RF measurements. A key feature of this technique is that R is performed under RF operation conditions similar to those found in power amplifiers under CW RF drive conditions. Investigations have shown that these dynamic RF I-Vs are independent of initial DC bias conditions and RF drive level for the MODFET structures investigated in this paper. These dynamic RF I-Vs can be directly compared with DC IVs to allow for the investigation of phenomena's like dispersion, RF breakdown and thermal effects etc.. To demonstrate their potential capability in the area of non-linear modelling these RF Ws have been used for non-linear parameter extraction of a relatively simple large signal model. A good comparison between the simulated and measured large signal behavior even for the higher harmonies has been achieved
A vector corrected large signal measurement setup based on a Microwave Transition Analyser has been developed to enable device output harmonic: anti waveform measurement with variable drive level, frequency, DC bias and fundamental load impedance. A novel capability of this system is the ability t o plot the device dynamic load lines during measureinent so that nonlinear effects can be investigated as a function of bias and load impedance in real time. Load line results are shown for a MESFET and an HBT device and the effect. of load impedance on device behaviour is described.
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