Relationship Between Measured and Intrinsic Transconductances of FET's

In exploratory study of FET's, such as the study of deep-submicrometer-channel FET's, carrier transport quantities are extracted from the measured transconductance of a FET. The extraction requires that the intrinsic transconductance of the device be calculated from the measured one, which is generally degraded by source and drain parasitic resistances. We have derived an equation that allows the calculation of the intrinsic transconductance of a FET from the measured transconductance, under the assumption that source and drain series resistances are independent of bias. The derivation does not assume zero drain conductance, nor does it involve any specific FET model. Therefore, the derived equation works in both saturation and linear regions of a FET, regardless of its channel length. The equation was tested by adding external resistors in series with source or drain of ultra-short-channel MOSFET's. Within the accuracy of the measurements, experimental results have proved that the equation is correct.