Noise parameter modeling for InP-based pseudomorphic HEMTs [InAlAs-InGaAs]

The effect of electron mobility (μ_n) on noise properties for InP-based pseudomorphic HEMTs has been analyzed based on the impedance field model. The analysis predicts that increasing μ _n improves the minimum noise figure (F_min) and associated gain not only because the unity current gain cut-off frequency increases but also because the source resistance is reduced. The analysis also predicts that increasing μ_n reduces the input noise resistance due to higher transconductance but hardly influences the noise-optimum impedance. Furthermore, it is predicted that the decrease in F_min with increasing μ_n becomes less significant above 11000 cm²/Vs due to larger diffusion noise. Calculated results compare well with the measured scattering and noise parameters for In_xGa_1-xAs(x=0.53, 0.7, and 0.8) channel devices. Similar dependence of noise parameters on μ_n is shown in the theoretical and experimental results