The use of quadrature signals, i.e. signals out of phase by 90 degrees with respect each other, is a common practice in areas such as wireless communications and digital signal processing. Quadrature signals are easy to deal with and they do possess the convenient feature of lterless image cancellation by simple arithmetic manipulation. Some sophisticated radio-receiver technologies, such as the phased array antennas, demand multi-phase high-frequency signals for interference cancellation. One possibility for generating phase shifts at RF frequencies is by fadding up quadrature signals. The accuracy of the phase shift realized in this way is sensitive to quadrature mismatch, thus a quadrature error < 3% must be guaranteed.