Impact of non-quasi-static effects on the high frequency small-signal behaviour of MOSFETs

In this paper, we investigate the impact of nonquasi-static (NQS) effects on the small-signal RF behaviour of MOSFETs. We observed that the transistor power gain G_Tmax is largely overestimated in the quasi-static model, whereas it is accurately predicted using a second order NQS model. Furthermore, we investigated the impact of channel width scaling on the transistor y-parameters for the second order NQS model. Accurate modelling results are obtained for MOSFETs with small channel widths. However, experimental results indicate that the effective gate resistance, stemming from the distributed nature of the MOS gate, tends to be lower than R_gate=WR_□ /(3L) at frequencies close to or larger than f=1/(R(□)C_oxW²). This was observed for transistors with a 25 μm channel width