Development of multi-band phased array transmitters in CMOS technology.

摘要

Phased array technology improves system capacity by means of electrical beam steering. Moreover, coherent power combination in the air, enabled in phased array systems, facilitates the integration of transmitter front-ends. This dissertation presents circuit techniques for implementing the key components of multi-band phased array transmitter subsystems, including phase shifters, pre-drivers, and medium power PAs, in 0.18mum CMOS technology.; The low quality factor of passive devices and small capacitance tuning ratio of varactors in CMOS represent challenges for phase shifter design. To enhance gain and loss compensation, an embedded broadband amplifier is designed with high impedances, and varactor-tuned LC networks are employed to provide both phase tuning and broadband impedance tuning. The first multi-band continuous phase shifter in CMOS has been achieved, and the measured phase tuning range is more than 180° over 2.4 GHz to 6 GHz.; A pre-driver amplifier is designed with a distributed topology. The adoption of high-pass T-sections enables multiple DC current paths and thereby relaxes the electromigration stress. The measured P1dB is up to 9.4 dBm. The amplifier works through the entire UWB bandwidth (3.1∼10.6 GHz) and is also qualified as a full-band UWB transmitter amplifier.; A device-level linearization technique is developed to effectively linearize medium power PAs without the penalty of large power consumption. The amplifier works from 4 GHz to 8 GHz. Compared with a conventional design, the amplifier with the proposed two-dimensional linearization technique achieves 11 dB suppression of IM3 and 5 dB improvement in P1dB. The amplifier is capable of delivering 19 dBm output power. The PAE is as high as 25%, which is the highest efficiency achieved among the reported CMOS broadband PAs to date.; The developed components have been assembled to form a two-way phased array transmitter subsystem. The measurements present a superior directivity as well as an improved output power over a single-path transmitter. A 6 dB array gain is achieved, and an EIRP of 21 dBm is measured. The feasibility of multi-band phased array transmitters in CMOS technology has been demonstrated.