A 1.4 GHz MMIC active isolator for integrated wireless systems applications

摘要

A GaAs MMIC active isolator with a center frequency of 1.4 GHz and a bandwidth of 200 MHz is described. The active isolator combines a low-noise amplifier and a Tee attenuator. The transistor used for the low-noise amplifier is a PHEMT D-FET with 5 gate fingers and a gate width of 50 μm. The characteristic impedance of the attenuator is 50Ω. This simple design results in an insertion loss of 2.5 dB, input and output return loss greater than 12 dB, reverse isolation of 31 dB and noise figure of 5.3 dB.