Active Phase Shifters for 60 GHz CMOS Radio
Ehsan Adabi Firouzjaei and Ali Niknejad
According to Shannon's capacity theorem, to get more data rate out of any communication system the bandwidth and/or signal to noise ratio (SNR) should be increased. Increasing the bandwidth is not a practical solution and multi path fading along with co-channel interference results in even more signal loss and less signal to noise and interference ratio (SNIR). One solution is to increase the transmit power which poses many challenges on the PA design on the transmitter side and also adds to the interference with other channels. Using a multi phased array antenna system will provide us with the beam steering capability that alleviates impairments such as fading, delay spread, and co-channel interference. Also in a multi antenna system automatic spatial power combining relaxes the PA design requirements which improves the power dissipation and efficiency of the transmitter. The goal of this research is to design an active phase shifter array for beamforming applications in the 60 GHz CMOS multi antenna radio system. This project will explore novel phase shifter architecture and design in a 90 nm CMOS technology. The proposed phase shifters consume nearly zero DC power, can be laid out in a compact manner at mm-wave frequencies, and are totally compatible with a digital CMOS process. Slow-wave transmission lines and MOS varactors are used to realize a small footprint and tenability. A complete beam forming transceiver will be realized in 90 nm technology and offer true time-day phase shifting capabilities. Applications include ultra high-speed wireless communication, electronically steerable pulse-based ultra-wideband communications, and medical imaging.
Figure 1: A multiple antenna transceiver employing beamforming for maximum gain and power combining