Measuring Frequency Response of a Single-Walled Carbon Nanotube Common-Source Amplifier

Frequency response function (FRF) showing ac gain from a single-walled carbon nanotube transistor is presented. A top-gated carbon nanotube FET (CNFET) is configured as a common-source amplifier and the FRF of the amplifier is measured. Evidence of unambiguous signal amplification is observed in time domain as well as frequency domain up to a unity voltage gain frequency of approximately 560 kHz. The observed roll-off in frequency is solely due to the RC time constant of the measurement apparatus. A specifically designed circuit-compatible SPICE model for the CNFET is used to model both dc and ac characteristic with the same set of physical parameters. Good agreement between measurement and simulation is obtained. For a device without the parasitic load capacitance, we predict an intrinsic unity voltage gain frequency of 29 GHz and a cutoff frequency of ~ 50 GHz.