Multi-gate pHEMT Modeling for Switch Applications

Multi-gate pHEMTs are extensively used in pHEMT switch circuits for wireless communication applications due to their size advantage. The intuitive modeling approach which considers a multiple-gate pHEMT to be a stack of single-gate FETs is far from adequate. Crucial factors in multi-gate pHEMT modeling include accurate leakage, CV below pinch-off, surface traps effects, and distribution features for large size switch FETs. In this paper we will address certain techniques to model both intrinsic FETs and extrinsic parasitic components. Our multi-gate pHEMT model was verified by comparisons of a variety of performances between modeled and measured data, including leakages, floating voltages, and CV curves on device level. In a switch application, comparisons of harmonics as a function of frequency at high driving power for both GSM and DCS bands show excellent agreement between model prediction and measured data as well.