The charge control concept of transistor operation is extended to include delay effects in an accurate, yet tractable, way. Defining the transit time τ
tas the ratio of the excess base charge to the collector current, the transform of the transit time τ
t(s) is approximated by

, where τ
Dis the delay time. For a one-dimensional, homogeneous-base transistor,

. The results of this technique are in good agreement with exact calculations.