Analytical noise model with the influence of shot noise induced by the gate leakage current for submicrometer gate-length high-electron-mobility transistors

A new high-frequency noise model which takes into account the influence of shot noise induced by the gate leakage current is introduced; the model accurately explains the observed minimum noise figure of submicrometer gate-length HEMT's as a function of frequency. Based on the steady-state Nyquist theorem for multiterminal devices recently reported, the minimum noise figure and the corresponding optimum source impedance of the microwave field effect transistors are expressed as functions of the measurable device parameters including noise spectral intensities and small-signal circuit parameters. The derived minimum noise figure can be shown to reduce to a simple form, i.e., an empirical relation with two fitting constant. The simple form and the derived formulas for the optimum source impedance can explain very well the experimental findings of the submicrometer gate-length high electron mobility transistors over the extended microwave frequency range and also provide the informations needed for the design of microwave low noise amplifiers.