Influence of drift region on the 1/f noise in LDMOS

The effect of drift region on the flicker noise in LDMOS devices in the linear and saturation regions is analyzed using measured data and device simulations. In the linear region, noise in the drift region arises from gate-drain overlap region and is significant for longer channel length devices. For shorter channel length devices, the sub-surface current flow in the gate-drain overlap region reduces the contribution of noise from the drift region. In the saturation region, noise is dependent on quasi-saturation condition, and reaches its lowest value only when the channel is saturated.