SEMICONDUCTOR DEVICE

摘要

A semiconductor device whose insertion loss is reduced and isolation characteristics are improved in a high frequency band by reducing the capacitance component when an FET is off is provided. FETs (30a, 30b) having a gate electrode with a gate length of not more than 0.8 mm are formed on a semiconductor substrate in which a buffer layer (24) having an impurity concentration of at least 10<10> cm<-3> and at most 10<14> cm<-3> is formed on a semi-insulating semiconductor (25) having at least 10<14> cm<-3> and at most 10<16> cm<-3> p-type or n-type impurities and an active layer (23) having a p-type or n-type impurity concentration of at least 10<15> cm<-3> and at most 10<17> cm<-3> is formed on the buffer layer. N FETs are combined with each other, and when 1 ≤ m ≤ n-1 (n and m are integers, n >1), a drain terminal of an m-th FET is connected to a source terminal of an (m+1)th FET, resistors (41a, 41b) are connected to the gate electrodes of all of the first to n-th FETs, and all of the other ends of the resistors are coupled to the same electric potential.