Determination of dispersion of output conductance and transconductance of InP HEMTs using low frequency S-parameter measurements

A frequency analysis of the output conductance and transconductance of 0.25 /spl mu/m InP based HEMTs is carried out using S-parameter measurements down to 500 Hz. It is shown that the kink in the output characteristics consists of two ranges of a reduced and an increased drain current and that the DC measured transconductance g/sub m.DC/ is generally lower than g/sub m.HF/. The dispersion of g/sub m/ is increased for higher drain voltages. It is also shown that the frequency limit of the dispersion of both g/sub d/ and g/sub m/ is increased for higher drain source voltages.