CMOS phase-shifting circuits for wireless beamforming transmitters

摘要

Two phase-shifting techniques for wireless beamforming transmitter applications are presented. The first performs quadrant selection using phase-offset local oscillators and fine-grain phase-shifting using RF phase shifters; a 5.2 GHz narrowband phase shifter is designed and fabricated in the CMOS subset of a 0.25 μm SiGe BiCMOS process. Using a tunable all-pass filter topology, it achieves a wide phase-shift range with low loss, and minimizes the number of on-chip passive elements. Measurement results show an insertion loss of 2 dB, an IIP3 of 1 dBm, and a total phase-shift range of 240°; power consumption of the core circuitry is 36.3 mW from a 2.5 V supply. The second approach, a phase-shifting up-converter based on Cartesian combining, achieves a 360° phase shift range that is independent of the operating frequency. Fabricated in 0.18 μm CMOS, it achieves 8 dB conversion gain, 4 dBm OP1 dB, 28 dB sideband rejection, and a 360° phase-shift range at 5.2 GHz without the explicit use of RF phase shifters. The power consumption of its core circuitry is 46.5 mW.