Wideband active quasi-circulator with tunable isolation enhancement

Abstract

An active quasi-circulator comprises three single-stage distributed amplifiers (DAs), in which two are for wideband transmission while the remaining one is for wideband signal cancellation. This quasi-circulator has wideband frequency operation and by optimising the bias current, tunable isolation enhancement between port 1 and port 3 is achieved. The experimental results show that this quasi-circulator has insertion losses of around 0 dB, return losses better than 10 dB at each port, minimum non-tunable isolation of around 15 dB from 0.8 to 2.2 GHz and tunable isolation of more than 40 dB between port 1 and port 3 from 0.8 to 2.2 GHz.

Keywords

• millimetre wave circulators
• signal denoising
• active quasi-circulator
• tunable isolation enhancement
• single-stage distributed amplifiers
• DA
• wideband transmission
• signal cancellation
• wideband frequency operation
• bias current
• frequency 0.8 GHz to 2.2 GHz