An improved vector modulator using Q-factor calibration for 5–6GHz beamforming receiver

This paper presents 5–6GHz beamforming receiver with Q-factor calibrated vector modulator to reduce phase error and amplitude mismatch. Q-factor of vector modulator IQ network has to be 0.95–1.05 in 5–6GHz to get under ±3 ° phase error. Proposed Q-factor calibration circuit selects the best capacitance and resistance for proper Q-factor in 5–6GHz. Beamforming receiver prototype, which is implemented in 0.13μm CMOS, has 0.98–1.03 Q-factor in 5–6GHz. The prototype beamforming receiver rms phase error is maximum 1.5°, and amplitude mismatch is maximum 0.47dB. In addition, noise figure is 3.8–4.6dB at 5–6GHz.