An approach to variable frequency characterization of high impedance devices such as a carbon nanotube field-effect transistor is presented. A top-gated nanotube transistor is configured as a common source amplifier, and frequency response function of the device is measured. Evidence of signal amplification is observed in time domain as well as frequency domain up to a unity gain frequency of approximately 600 kHz. The observed roll-off in frequency is solely due to the measurement setup. (c) 2006 American Vacuum Society.