Reliable Technology Evaluation of SiGe HBTs and MOSFETs: fMAX Estimation From Measured Data

Maximum oscillation frequency (f
_MAX
) of mmwave transistors is one of the key figures of merit (FOMs) for evaluating the HF-performance of a given technology. However, accurate measurements of f
_MAX
are very difficult. Determination of f
_MAX
is significantly affected by the measurement uncertainties in the admittance (y) parameters. In order to get rid of the random measurement error and to obtain a reliable and stable f
_MAX
value, the frequency dependent y-parameters are described by rational functions formulated from the small-signal hybrid π-model of the transistor under investigation. The parameters of these functions are determined following a least square error technique that minimizes the functional error with the measured data. The approach is especially useful for a fast and reliable evaluation of f
_MAX
value. Devices from two different SiGe and an FDSOI (Fully Depleted Silicon On Insulator) MOS technology are measured and stable f
_MAX
values are estimated following this approach.