A quadrature oscillator using simplified phase and amplitude calibration

A quadrature oscillator using automatic calibration of phase and amplitude is presented. It is shown that phase errors in a quadrature oscillator will create an amplitude difference between the outputs. The proposed calibration scheme use on- chip amplitude detectors connected in a negative feedback loop to detect and compensate these amplitude differences. The calibration scheme can be implemented using small chip area and low current consumption compared to other calibration schemes. A quadrature oscillator using the proposed calibration is simulated using a 0.18 mum CMOS process to verify the feasibility of the proposed method.