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 degrees 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 0.13 mu m CMOS, has 0.98 - 1.03 Q-factor in 5 - 6GHz. The prototype beamforming receiver rms phase error is maximum 1.5 degrees, and amplitude mismatch is maximum 0.47dB. In addition, noise figure is 3.8 - 4.6dB at 5 - 6GHz.