A new large signal model for HEMT's and MES-FET's, capable of ,modeling the current-voltage characteristic and its derivatives, including the characteristic transconductance peak, gate-source and gate-drain capacitances is described. Model parameter extraction is straightforward and is demonstrated for different submicron gate-length HEMT devices including different d-doped pseudomorphic HEMTs on GaAs and lattice matched to InP, and a commercially available MESFET. Measured and modeled dc and S-parameters are compared and found to coincide well.

3, a maximum output power of 33 dBm and a drain efficiency of 63% were measured at 5.5 GHz.To investigate the GaN capabilities for radar system, an UltraWide-Band (UWB) HPA to operate from 0.8 GHz to 4 GHz was designed [5]. The experimental results reported in Figure 4 have shown an output power higher than 32.5 dBm in the overall band, with associated drain efficiency higher than 45%.Finally, for communication applications, for the first time a dual band 2nd HT HPA was designed to simultaneously (i.e. concurrency) operate at 2.45 GHz and 3.3 GHz [9]. In this case a drain efficiency of 53% and 46%, with an output power of 33 dBm and 32.5 dBm at 2.45 GHz and 3.3 GHz, respectively, were measured and here reported in Figure 5. CONCLUSIONIn this contribution the features of GaN technology (provided by Selex-SI) for power applications were explored from the designer point of view. The role of the active device key parameters was highlighted underlining the potentials of GaN HEMT. As a demonstration several experimental results of different power amplifiers were reported to highlight both, the capabilities and/or drawbacks of such material. ACKNOWLEDGMENTSThe authors wish to acknowledge Dr. A. Cetronio, C. Lanzieri, and M. Peroni from Selex-SI for the technological support and Dr. A. Nanni and Dr. A. Serino for the device modeling support.

This paper describes cryogenic broad-band amplifiers with very low power consumption and very low noise for the 4-8-GHz frequency range. At room temperature, the two-stage InP-based amplifier has a gain of 27 dB and a noise temperature of 31 K with a power consumption of 14.4 mW per stage, including bias circuitry. When cooled to 15 K, an input noise temperature of 1.4 K is obtained at 5.7 mW per stage. At 0.51 mW per stage, the input noise increases to 2.4 K. The noise measurements have been repeated at different laboratories using different methods and are found consistent.

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In the paper, the nonlinear model of a microwave transistor is extracted from large-signal measurements acquired under “dynamic-bias” operation. Specifically, the transistor is driven by low-frequency large signals while a high-frequency tickle is applied on top of them. The low-frequency large signals, along with the dc bias voltages, set the large-signal operating point which represents a dynamic-bias condition for the device under test. Thanks to this technique, one can get at once and separately the nonlinear currents and charges of the transistor as a result of a very few nonlinear measurements. Additionally, the proposed technique allows one to accurately reconstruct the time-domain waveforms at the device-under-test terminals while the frequency of the tickle can be set as high as the bandwidth of today’s vector calibrated nonlinear measurement systems (i.e., 67 GHz). The approach, which is general and independent of device technology, is applied on a 0.15- m GaAs pHEMT specifically designed for resistive cold-FET mixer applications

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