New results of rf and microwave PIN diode modeling are presented which
help to predict and explain impedance-frequency characteristics of mu
ltilayer semiconductor control devices at low and high power levels. T
wo techniques of different complexity based on modified physical-topol
ogical and equivalent-circuit models are developed and used. ''Anomalo
us'' amplitude characteristics of the devices including a bistability
phenomenon are investigated. Two main mechanisms are shown to be respo
nsible for the diode impedance behavior at high frequencies. The first
one is connected with frequency-dependent properties of the voltage d
ivider formed by the depleted and undepleted regions of the diode base
, and with their interaction at large-signal levels. The second one is
related to the transit-time phenomenon in the depletion region which
results in a reduction of the effective voltage across this region. A
new specific parameter is discussed - the characteristic frequency, wh
ich determines the range of a rapid and substantial change in the diod
e impedance properties. The concepts developed in this paper are suppo
rted by a broad scope of numerical simulations and are also consistent
with real device behavior. (C) 1998 Elsevier Science Ltd. All rights
reserved.