With the widespread deployment of 5G and Internet of Things in the foreseeable future, billions of devices will be connected to each other. The demand for high data rate wireless communication has been ever-increasing. New wireless communication schemes for high data rate and high spectral efficiency are desired, among which full duplex is an emerging and promising research topic.

A full duplex wireless system transmits and receives signal at the same time on the same frequency channel. Therefore, the biggest challenge towards a full duplex transceiver is the large self-interference from the local transmitter (TX). The self-interference needs to be suppressed to the receiver’s noise floor to maintain the same signal-to-noise ratio (SNR) of the receiver (RX) compared with in the half du...[ Read more ]

With the widespread deployment of 5G and Internet of Things in the foreseeable future, billions of devices will be connected to each other. The demand for high data rate wireless communication has been ever-increasing. New wireless communication schemes for high data rate and high spectral efficiency are desired, among which full duplex is an emerging and promising research topic.

A full duplex wireless system transmits and receives signal at the same time on the same frequency channel. Therefore, the biggest challenge towards a full duplex transceiver is the large self-interference from the local transmitter (TX). The self-interference needs to be suppressed to the receiver’s noise floor to maintain the same signal-to-noise ratio (SNR) of the receiver (RX) compared with in the half duplex mode.

Circulators, as the first stage in the receiver chain, play an important role in providing TX-RX isolation and relaxing dynamic range requirements for later stages. Recently, research on mm-wave circulators for full duplex radios has been attracting attention. In this thesis, an active circulator based on an active gyrator will be presented.

The proposed circulator consumes lower power compared with modulation-based circulators while overcoming the high power and non-linearity problems of the conventional active circulators. Fabricated in TSMC 65nm CMOS process, the circulator prototype measures 40dB isolation over the 65.7~66.0GHz bandwidth and has a +10.8dBm TX-ANT IIP3, +11.5dBm ANT-RX IIP3 and 6dB ANT-RX noise figure while consuming 8mW from 1.0V power supply. It achieves the lowest reported power consumption for 60GHz circulators with comparable isolation and noise performance.