This paper presents a new approach for the definition and identification of a transistor model suitable for low-noise amplifier (LNA) design. The resulting model is very robust to layout modifications (i.e., source degeneration) providing accurate predictions of device noise-performance and small-signal parameters. Moreover, the described procedure is very robust since it does not require any numerical optimization, with possibly related problems like local minima and unphysical model parameters. The adopted model topology is based on a lumped element parasitic network and a black-box intrinsic device, which are both identified on the basis of full-wave lectromagnetic simulations, as well as noise and -parameter measurements. The procedure has been applied to three GaN HEMTs having different peripheries and a Ku-band LNA has been designed, demonstrating a very good agreement between measurements and predicted results

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A large-signal measurement setup with sinusoidal excitation is used for the characterization of low-frequency dispersive phenomena in III-V FET devices. This low-cost setup operates in the MHz frequency range and its components are easily available in most research laboratories. A dispersive model of the dynamic drain current, taking into account the non linear behaviour of charge trapping phenomena, is identified for an AlGaN/GaN HEMT on the basis of the proposed characterization setup.

A set of monolithic microwave integrated circuits (MMICs) has been successfully developed by using a qualified European GaN HEMT technology. In particular a high power amplifier (HPA), a low noise amplifier (LNA) and a single pole double throw (SPDT) switch have been designed, manufactured and tested. The presented chipset is very suitable for integration in future GaN-based T/R module Frontend for spaceborne Xband SAR applications. In particular, the MMIC HPA integrates two stages of gain in 5.5 x 4.0 mm2 of area. Its measured performance is an output power of 27 W, a PAE of 36% with a linear gain greater than 24 dB from 8.8 GHz to 10.2 GHz. The MMIC LNA integrates three stages of gain in 3.0 x 2.02 mm2 of area. Its measured performance is a small signal gain greater than 23 dB with an associated noise figure of 1.6 dB in the frequency range from 7.4 to 11.4 GHz. Besides, its output power at 1 dB of gain compression is greater than 22 dBm. The MMIC SPDT switch exploits a robust asymmetrical absorptive/reflective topology in 3.0 x 1.0 mm2 of area. The chosen topology allows obtaining different functionalities of each switched branch. In the frequency range from 8.4 GHz to 10.8 GHz its measured performance is an insertion loss lower than 1 dB for both tx and rx path, and tx-mode rx-mode isolations better than 20 dB and 28 dB respectively. Besides, the tx path 1 dB insertion loss compression occurs at nearly 20 W of input power.Index Terms-GaN; low noise amplifier; power amplifier; SPDT switch; X band; T/R module