Design of low phase shift attenuator applied to analog self-interference cancellation circuit

A voltage variable attenuator applied to 5G all full-duplex communication system is proposed. There will be the self-interference signal that comes from the mismatch of the front-end antenna in the system. The self-interference signal leaked after the signal passing through the circulator, the problem is to eliminate the self-interference signal in the circuit, and the attenuator plays a very important role in it.We compares the designed attenuator with the traditional reflective attenuator, the simulation result can be within the attenuation range of 4.5~42.5dB, the change range of the output phase can be variable within 90°.The measured reach the adjustable range of 4~38dB attenuation and the phase of fluctuation within 95°. The attenuator reduces the influence of the circuit phase.