A simulation method has been developed to study the fabrication tolera
nces of a passive duplexer on InP substrate which could be a part of a
n OEIC module. This method, based on a Taylor's series expansion, is f
ast enough to estimate the effect produced on the crossover power when
a simultaneous variation of the duplexer parameters take place. It se
ems to be very useful, particularly during a repetitive control of the
device characteristics.