New empirical relation for MOSFET noise unified over linear and saturation regions

This paper proposes an empirical relation, which represents noise bias condition dependence for a silicon N-channel MOSFET. No matter whether the MOSFET is operated in linear or saturation region, bias condition dependence is found to be well described by a power function of voltage gain. By introducing a device's intrinsic noise emf v_nc(ƒ), which is independent from bias condition, and empirical parameter β, input-referred noise voltage v_ni(ƒ) is clarified to be a function of v_nc(ƒ), β, and voltage gain , i.e. . This relation implies that noise voltage depends implicitly on bias condition through voltage gain, because transconductance g_m and drain-source differential conductance g_DS depend on bias condition. If β − 1 value is negligible, v_ni(ƒ) = v_nc(ƒ) is almost independent from bias condition, whereas, if β − 1 value is not negligible, bias condition dependence for v_ni(ƒ) appears to be observed. The β deviation from unity, which characterizes bias condition dependence, measures the difference between signal amplification and noise amplification.