Direct White Noise Characterization of Short-Channel MOSFETs

On-wafer evaluation of white thermal and shot noise in nanoscale MOSFETs is demonstrated by directly sensing the drain current under zero- and nonzero-drain-bias (
${V}_{d}$
) conditions for the first time, without recourse to a hot noise source, commonly needed in noise figure measurement. The dependence of white noise intensity on the drain bias clearly shows thermal noise at
${V}_{d} \boldsymbol = {0}$
V and shot noise at
${V}_{d} > {0}$
V with its gate-bias-dependent suppression. An empirical expression for the Fano factor (shot-noise suppression factor) that is well-behaved even at
${V}_{d} \boldsymbol = {0}$
V exactly and suitable for measurement-based evaluation is proposed. The direct measurement approach could allow more accurate and predictive noise modeling of RF MOSFETs than has conventionally been possible.