Small-signal performance and modeling of sub-50 nm nMOSFETs with fT above 460-GHz

We have fabricated and tested the performance of sub-50 nm gate nMOSFETs to assess their suitability for mixed signal applications in the super high frequency (SHF) band, i.e. 3–30 GHz. For a 30 nm × 40 μm × 2 device, we found fT = 465 GHz at Vds = 2 V, Vg = 0.67 V, which is the highest cut-off frequency reported for a MOSFET produced on bulk silicon substrate so far. However, our measurements of fmax and noise figure indicate that parasitics impose limitations on SHF operation. We also present a high frequency ac model appropriate to sub-50 nm gate length nanotransistors, which incorporates the effects of the parasitics. The model accurately accounts for measurements of the S- and Y-parameters in the frequency range from 1 to 50 GHz.