Charge control approach to the small signal theory of field-effect devices

The operation of a field-effect device is described in terms of the total charge in the channel region. The analysis is primarily developed for the small-signal operation for which the charge control equations are linear and have constant coefficients. The complete expressions for the small signal admittance parameters are obtained in both the linear and the pinch-off regions leading directly to equivalent circuits. It is believed that the charge control approach not only simplifies the mathematics involved, but provides new insights into device operation as well.