A Novel Bias‐Included Broadband Combined Model for GaN HEMTs in Admittance Domain

This paper presents a new bias‐included broadband combined model in the admittance domain for GaN HEMT devices. The proposed model extends the CPL‐Y/CPL‐QY broadband admittance‐domain formulation from fixed‐bias operation to multi‐bias operation by explicitly incorporating the gate and drain bias voltages into the coefficient‐generation process. Instead of extracting an independent broadband model at each bias point, the proposed approach represents the admittance‐domain model coefficients as functions of input power, load condition, frequency, gate bias, and drain bias. Therefore, a single compact coefficient set can be used to describe the behavior of the device over the considered frequency and bias ranges. A canonical piecewise linear (CPL) function is used to implement the intrinsic part of the model, while the extrinsic parasitic network is retained to facilitate access to the intrinsic device plane as required by circuit designers. Both linear and quadratic admittance‐domain expansions are examined. The model is validated using a commercial 10‐W GaN HEMT. The results demonstrate that the proposed bias‐included CPL‐Y and CPL‐QY models can predict device behavior under different gate and drain bias conditions, while maintaining the broadband interpolation and extrapolation capability of the original admittance‐domain CPL framework.