A signal generator for generating signals that are spaced .pi./X rad apart, where X is an integer. The signal generator includes at least one delay cell with a delay that approximately corresponds to a phase shift .pi./X rad for a given signal. The signal generator also includes at least one phase detection system receiving at least two signals with a phase difference of approximately .pi./2 rad with respect to one another from said at least one delay cell and generating a feedback signal that is communicated to the at least one delay cell to adjust the phase relationship of the at least two signals. Such signal generators are used in radio frequency up-converters or down-converters.