  In this thesis, set-valued maps are considered to model the $i-v$
characteristics of semiconductors like diode, and transistor. Using the circuit
theory laws, a generalized equation is obtained. The main concern of the thesis
is to investigate how perturbing the input signal will affect the output
variables. The problem is studied in two cases: the static case, where the
input signal is a DC source; and the dynamic case, where there exists an AC
source in the circuit.
  In the static case, the problem can be reduced to the existence or absence of
local stability properties of the solution map, like the Aubin property,
isolated calmness, and calmness, or metric regularity for the inverse map. Some
tools from variational analysis are used to provide necessary and/or sufficient
conditions that guarantee these properties. In the dynamic case, those
pointwise results are used to obtain descriptions for regularity properties of
the solution trajectories in function spaces.
