UCLA

Many portables and IoT devices employ multi-radio systems. The number of differenttransceivers/antennas is increasing, especially with multi-antenna and phased array systems. Operating multiple transmitters, power amplifiers, and antennae in close physical proximity, simultaneously, in nearby frequency banks leads to unwanted TX-to-TX signal coupling which, in the presence of power amplifier non-linearity, causes intermodulation distortion products (IMD3) that are problematic e.g., causing transmit spectral mask violations. There is a strong need to eliminate or suppress such TX-to-TX signal coupling and the IMD3 products to satisfy FCC spectral mask requirements and enable simultaneous multi-band transmission. Prior work has explored TX-TX cancellation for simultaneous transmission of NB and WLAN signals using analog techniques. However, the analog implementation is bulky and power hungry. A digital implementation for TX-TX self-interference cancellation can alleviate these issues. This thesis explores the design and implementation of a Digital-to-Time-Converter(DTC) as a part of digital TX-TX cancellation for the simultaneous transmission of NB and WLAN signals in 22FDX Technology. The designed DTC demonstrates consistent performance across process and temperature corners without calibration and has the necessary step-size and range to meet the TX-TX cancellation requirement.