An Image-Band-Rejection Technique for Error Detection of On-Chip Quadrature Phases

An image-band-rejection technique for extraction of quadrature phase errors is presented in this paper. Based on the relationship between the image rejection ratio and the baseband in-phase/quadrature phase imbalance, the phase error of on-chip quadrature local-oscillation (LO) signals can be characterized without complicated measurement setup and calibration procedures while maintaining excellent testing accuracy relatively insensitive to the amplitude errors. Using a standard 0.18-mum CMOS technology, a 5-GHz quadrature-phase voltage-controlled oscillator is fabricated as the device-under-test for demonstration. Compared with the benchmark results from time-domain measurement by a high-speed oscilloscope, the proposed technique provides effective phase error detection with a deviation less than 0.5^deg in the experimental results for various LO phase conditions.