A circuit architecture for generation of amplitude and phase matched signals is described, which is primarily intended for the generation of quadrature signals, for example local oscillator signals, as required in many electronic systems. Using a single reference signal as an input, two output signals are generated at the same frequency. The relative amplitudes of these signals contain phase error information. An error signal is derived by amplitude comparison, and then fed back to a phase control element in a closed loop manner. The method proposed ensures that when the output amplitudes are equal then the output signals will be in phase quadrature. All signal processing is performed at the fundamental frequency, enabling wider bandwidth and higher frequency operation to be achieved, than could otherwise be realised using standard circuits based on frequency dividers.