Based on the charge control theory

an accurate analytical model for the dc I-V characteristics and small signal parameters of an AlGaN/GaN high electron mobility transistor(HEMT) is developed considering the effects of polarization and parasitic source-drain resistances.Results show that the joint effects of spontaneous and piezoelectric polarization on the performance of the device are highly dominant.The proposed model predicts a maximum saturation current of 1370mA/mm at a gate bias of 2V for a 1.0μm Al

0.2

Ga

0.8

N/GaN HEMT.The calculated results also indicate that higher saturation current

transconductance

and cutoff frequency can be achieved by lowering the parasitic resistances.The comparison between simulations and physical measurements shows a good agreement.The model is simple in calculations and distinct in

physical mechanism

therefore suitable for design and research of microwave device and circuit.