To extract extrinsic resistances, conventional cold-FET methods require additional DC measurements or channel technological parameters. Additionally, the methods need at least two sets of cold-FET S-parameters measured at different cold-FET bias conditions in order to completely determine gate and drain pad capacitance as well as extrinsic gate, source and drain inductance and their resistances. One set of S-parameters handles the extraction of extrinsic inductances, and the other set extracts the gate and drain pad capacitance. To be free from additional DC measurement or channel technological parameters and reduce the number of sets of cold-FET S-parameters, we propose a cold-FET method that can extract all the extrinsic elements including the gate and drain capacitance, using only one set of cold-FET S-parameters. The method has shown excellent agreement between modeled and measured S-parameters up to 62 GHz at 56 different normal operating bias points.

We propose a new technique that is able to extract the small-signal equivalent-circuit elements of high electron mobility transistors (HEMTs) without causing any gate degradation. For the determination of extrinsic resistance values, unlike other conventional techniques, the proposed technique does not require an additional relationship for the resistances. For the extraction of extrinsic inductance values, the technique uses the R-estimate, which is known to be more robust relative to the measurement errors than the commonly used least-squares regression. Additionally, we suggest an improved cold HEMT model that seems to be more general than conventional cold HEMT models. With the use of the improved cold HEMT model, the proposed technique extracts the extrinsic resistance and inductance values.