Scalable Small Signal and Noise Modeling of InP HEMT for THz Application

Scalable small signal and noise modeling for 90nm InP high electron mobility transistor (HEMT) is proposed in this paper. Analytical expressions for the noise parameters of the intrinsic part are derived from an accurate small signal and noise equivalent circuit model. The experimental and theoretical results show that at the same bias condition, good scaling can be achieved between the HEMTs with different gate widths. Model verification is carried out by comparison of measured and simulated S-parameters up to 325 GHz and noise parameters up to 40GHz. Good agreement is obtained for 90 nm gate-length devices of gate widths including $2\times 15\,\,\mu \text{m}$ , $2\times 20\,\,\mu \text{m}$ and $2\times 25\,\,\mu \text{m}$ gate width (number of gate fingers $\times $ unit gate width $\times $ cells). The proposed model can be used to predict the S-parameters and noise performance of HEMTs with different geometry accurately.