New empirical relation for MOSFET [formula omitted] noise unified over linear and saturation regions

Abstract

This paper proposes an empirical relation, which represents 1 ƒ 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 1 ƒ noise emf v nc (ƒ) , which is independent from bias condition, and empirical parameter β, input-referred 1 ƒ noise voltage v ni (ƒ) is clarified to be a function of v nc (ƒ) , β, and voltage gain g m g DS , i.e. v nc (ƒ)( g m g DS ) β−1 . This relation implies that 1 ƒ 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 1 ƒ noise amplification.