A novel extraction methodology is proposed to distinguish between the extrinsic and intrinsic capacitances of wide GaN HEMTs. This approach is based on the experimental observation that the real parts of the impedance parameters of such devices increase at high-frequency. The mathematical analysis clearly shows that this so far uninvestigated behavior can be attributed to the extrinsic capacitances

The extrinsic input and output capacitances of the field effect transistor small-signal equivalent circuit are typically extracted from the low frequency admittance parameters under ''cold'' pinch-off condition. Despite that, these two capacitances play a significant role also at high frequencies. Intuitively, a first hint of explanation stems from the high frequency reduction of their admittance values connected in parallel to the input and the output of the rest of the equivalent circuit. In particular, the extrinsic capacitances can cause an increase of the real parts of the impedance parameters at high frequencies. This article is aimed at developing an extensive experimental and mathematical analysis based on a comparative study of this behavior for GaN high electron mobility transistor (HEMT) devices up to the millimeter-wave range. The results of this analysis can be applied for estimating the extrinsic capacitances. The main benefit of this modeling technique is that the extrinsic output capacitance can be separated from the intrinsic output capacitance, which can play a significant role especially in case of large devices. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000-000, 2012.

No abstract

An RF-MEMs based tri-band GaN power amplifier with state-of-the-art performance is presented. The active device is a low-cost GaN-on-Si transistor with a plastic package. A dedicated broadband output matching network is designed to provide the desired waveform at the device intrinsic level. The frequency reconfigurability is implemented with one RF-MEMS at the input stage. Measured results show a 45, 28 and 46% power added efficiency (PAE) for an output power of 5.6, 3.0 and 4.5 W at 1.4, 2.5 and 3.6 GHz, respectively. Furthermore, the power amplifier exhibits a high drain efficiency of more than 46% across 1.3 -1.4 and 3.4 -3.7 GHz whilst delivering an output power of more than 4.3 W.

No abstract